Leptocephali: Part 9, Volume 2 9781933789330

Table of contents :
Table of Contents - Volume Two
Introduction to Leptocephali
The Evolutionary Significance of the Leptocephalus Larva
Orders Anguilliformes and Saccopharyngiformes Leptocephali
Order Notacanthiformes Leptocephali
Order Elopiformes. Families Elopidae, Megalopidae, and Albulidae: Leptocephali
Unidentified Leptocephali
Literature Cited
INDEX

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Fishes of the Western North Atlantic

PUBLICATIONS OF THE SEARS FOUNDATION FOR MARINE RESEARCH, YALE UNIVERSITY The Sears Foundation for Marine Research at Yale University was established in 1937 by Albert E. Parr, director of Yale's Bingham Oceanographic Laboratory, through a gift from Henry Sears, to promote research and publication in marine sciences. The Foundation's Memoirs, inaugurated in 1948, remain important references. In 1959 the Bingham Oceanographic Collection was incorporated into the Yale Peabody Museum of Natural History. Distributed by Yale University Press www.yalebooks.com I yalebooks.co.uk MEMOIRI FISHES OF THE WESTERN NORTH ATLANTIC

Part One Lancelets, Cyclostomes, Sharks Part Two Sawfishes, Guitarfishes, Skates and Rays, Chimaeroids Part Three Soft-rayed Bony Fishes: Orders Acipenseroidei, Lepisostei, and Isospondyli Sturgeons, Gars, Tarpon, Ladyfish, Bonefish, Salmon, Charrs, Anchovies, Herring, Shads, Smelt, Capelin, et al. Part Four Soft-rayed Bony Fishes: Orders Isospondyli and Giganturoidei Argentinoids, Stomiatoids, Pickerels, Bathylaconids, Giganturids Part Five Orders Iniomi and Lyomeri Lizardfishes, Other Iniomi, Deepsea Gulpers Part Six Orders Heteromi (Notacanthiformes), Berycomorphi (Beryciformes), Xenoberyces (Stephanoberyciformes), Anacanthini (Gadiformes) Halosauriforms, Killifishes, Squirrelfishes and Other Beryciforms, Stephanoberyciforms, Grenadiers Part Seven Order Iniomi (Myctophiformes) Neoscopelids, Lanternfishes, and Atlantic Mesopelagic Zoogeography Part Eight Order Gasterosteiformes Pipefishes and Seahorses Part Nine, Volume One Orders Anguilliformes and Saccopharyngiformes Part Nine, Volume Two Leptocephali Part Ten Order Beloniformes Needlefishes, Sauries, Halfbeaks, and Flyingfishes MEMOIR II THE ELEMENTARY CHEMICAL COMPOSITION OF MARINE ORGANISMS

by A. P. Vinogradov

MEMOIR

SEARS FOUNDATION FOR MARINE RESEARCH

Number I

Fishes of the Western North Atlantic

PART NINE

Volume One: Orders Anguilliformes and Saccopharyngiformes Volume Two: Leptocephali VOLUME TWO Leptocephali ANGUILLIFORMES, SACCOPHARYNGIFORMES, NOTACANTHIFORMES, ELOPIFORMES

NEW HAVEN SEARS FOUNDATION FOR MARINE RESEARCH, YALE UNIVERSITY

Yale ISBN 978-1-933789-20-0 (pbk.) ISBN 978-1-933789-33-0 (e-book) ISBN 978-0-935868-45-6 (cloth) Part Nine, Volume 2 issued in paperback by the Peabody Museum of Natural History, Yale University, New Haven, Connecticut 06511 USA Printed on acid-free paper First published in hardcover © 1989 Sears Foundation for Marine Research, Yale University Distributed by Yale University Press NEW HAVEN AND LONDON

The Library of Congress has catalogued the hardcover edition as follows: Fishes of the western North Atlantic Volume One. Orders Anguilliformes and Saccopharyngiformes Volume Two. Leptocephali Edited by Eugenia B. Bohlke 1. Order Anguilliformes 2. Order Saccopharyngiformes 3. Leptocephali Includes Bibliography and Index QH91.Y3 ISBN 0-935868-45-3 Printed in the United States of America

Fishes of the Western North Atlantic Editor

EUGENIA B. BOHLKE

Authors EUGENIA B. BOHLKE

CATHERINE H. ROBINS

Academy of Natural Sciences of Philadelphia Philadelphia, Pennsylvania

Rosenstiel School of Marine and Atmospheric Sciences, Miami, Florida

JAMES E. BOHLKEf

C. RICHARD ROBINS

Academy of Natural Sciences of Philadelphia Philadelphia, Pennsylvania

Rosenstiel School of Marine and Atmospheric Sciences, Miami, Florida

MARK M. LEIBY

DAVID G. SMITH

Florida Department of Natural Resources St. Petersburg, Florida

Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts

KENNETH A. TIGHE

JOHN E. McCOSKER

California Academy of Sciences San Francisco, California

E. BERTELSEN

National Museum of Natural History Washington, D.C.

Zoological Museum, University of Copenhagen Copenhagen, Denmark

J0RGEN G. NIELSEN

Zoological Museum, University of Copenhagen Copenhagen, Denmark

WILLIAM H. HULET

Rosenstiel School of Marine and Atmospheric Sciences Miami, Florida

Illustrator MARY H. FUGES

Academy of Natural Sciences of Philadelphia Philadelphia, Pennsylvania

NEW HAVEN SEARS FOUNDATION FOR MARINE RESEARCH, YALE UNIVERSITY

Editorial Board Chairman

BRUCE B. COLLETTE Systematics Laboratory National Marine Fisheries Service Washington, D.C.

DANIEL M. COHEN

WILLARD D. HARTMAN

WILLIAM N. ESCHMEYER

THEODORE W. PIETSCH

Los Angeles County Museum of Natural History Los Angeles, California

California Academy of Sciences San Francisco, California

ROBERT H. GIBBS, JR.f

Smithsonian Institution Washington, D.C.

Sears Foundation for Marine Research Yale University New Haven, Connecticut

University of Washington Seattle, Washington

WILLIAM J. RICHARDS

National Marine Fisheries Service Miami, Florida

KEITH S. THOMSON Academy of Natural Sciences of Philadelphia Philadelphia, Pennsylvania

Editor Emeritus ALBERT E. PARR Wilder, Vermont

Table of Contents - Volume Two Introduction to Leptocephali. By DAVID G. SMITH Significance of the Leptocephalus Larva. By WILLIAM H. HULET and C. RICHARD ROBINS Orders Anguilliformes and Saccopharyngiformes: Leptocephali. By DAVID G. SMITH Family Synaphobranchidae: Leptocephali. By DAVID G. SMITH Family Moringuidae: Leptocephali. By DAVID G. SMITH Family Nettastomatidae: Leptocephali. By DAVID G. SMITH Family Congridae: Leptocephali. By DAVID G. SMITH Family Ophichthidae: Leptocephali. By MARK M. LEIBY Family Anguillidae: Leptocephali. By DAVID G. SMITH Family Muraenidae: Leptocephali. By DAVID G. SMITH Family Derichthyidae: Leptocephali. By DAVID G. SMITH Family Serrivomeridae: Leptocephali. By KENNETH A. TIGHE Family Nemichthyidae: Leptocephali. By DAVID G. SMITH Family Chlopsidae: Leptocephali. By DAVID G. SMITH Family Heterenchelyidae: Leptocephali. By DAVID G. SMITH Family Cyematidae: Leptocephali. By DAVID G. SMITH Families Saccopharyngidae, Eurypharyngidae, and Monognathidae: Leptocephali. By DAVID G. SMITH Order Notacanthiformes: Leptocephali. By DAVID G. SMITH Order Elopiformes: Families Elopidae, Megalopidae, and Albulidae: Leptocephali. By DAVID G. SMITH Family Elopidae: Leptocephali Family Megalopidae: Leptocephali Family Albulidae: Leptocephali Unidentified Leptocephali. By DAVID G. SMITH Literature Cited

INDEX

Vll

657 669 679 682 699 704 723 764 898 900 917 921 925 933 943 944 948 955 961 962 968 970 973 983

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Introduction to Leptocephali D A V I D G. SMITH Introduction. The leptocephalus larvae of eels and other elopomorph fishes are so distinct from the adults that their study almost constitutes a separate science. Moreover, they are such unusual larvae that most traditional larval-fish workers have avoided them. "Leptocephalology" has thus followed its own idiosyncratic history. The anatomy of the leptocephalus is described in detail by Hulet (1978), and its evolutionary significance is discussed elsewhere in this volume (Hulet and Robins, p. 669). In this section I shall concern myself mainly with general morphology and variation, development, collection and preservation, identification, and history. History. If Aristotle or anyone else in the ancient world knew about leptocephali, there is no record of it. None of the naturalists of Renaissance Europe mentioned them either. The first leptocephalus of record was collected in or shortly before 1763 by a man named William Morris on the north coast of Wales. Morris gave it to the British naturalist Thomas Pennant, who in turn sent it to Lorenz Theodor Gronow. Gronow (1763: 135) published the first description and gave it the name Leptocephalus. Gronow's work was later rejected for nomenclatural purposes, and the name Leptocephalus officially dates from Scopoli (1777: 453). Pennant (1776: 158, pi. 25, fig. 67) meanwhile published on it himself, using the vernacular term "morris." The specimen attracted some interest, and Gmelin (1789: 1150) finally gave it a specific name, Leptocephalus morrisii, after its discoverer. For the next century, leptocephali were treated as a distinct group of fishes. As new species were discovered, they were placed either within the genus Leptocephalus or into new genera created expressly for them. Most of the work on lepto-

cephali during the 19th century was done on material from the Mediterranean, partly because many scientists were working there and partly because the Strait of Messina proved to be a uniquely suitable place to collect them. Rafinesque (1810b) named several new forms. Others who described new leptocephali during this period include Risso (1810), Cocco (1829), Lesson (1830), Costa (1844,1856), Kolliker (1853), Peters (1859, 1864), and Bleeker (1864b). The most important publication, however, was that of Kaup (1856b), who treated 18 species, both his own and those described by others. Shortly after the midpoint of the 19th century, the idea began to take hold that leptocephali were larval forms of something else. Cams (1861: 125, quoted in Gill, 1864: 207) thought that they might be "... Ophidians or other compressed forms, (Cepola, and so on.)." Gill (1864: 207) apparently was the first to suggest that leptocephali were larval eels, and he specifically suggested that Leptocephalus morrisii was the young of Conger conger. Delage (1886: 699) confirmed Gill's hypothesis by raising a specimen through metamorphosis in an aquarium. Grassi and Calandruccio (1892) made an even more momentous discovery when they found that Kaup's Leptocephalus brevirostris was the larva of the freshwater eel, Anguilla anguilla. The emphasis from this point forward was placed on identification of leptocephali. Much of the initial work was done in Italy, mainly by Facciola and by Grassi and his collaborators. The results of this early period of identification were summarized in Grassi's (1913) Metamorphosi del murenoidi. Despite all the progress, many leptocephali still could not be identified. This was particularly true outside the Mediterranean, 657

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where the fish fauna in general was still poorly known. Descriptive catalogs of new species of Leptocephalus therefore continued. The most important of these were the works of Stromman (1896) and Lea (1913). Lea actually did identify several species, but others were necessarily listed as species of Leptocephalus. The Italian tradition begun by Facciola and Grassi was continued during the 1920's and 1930's by their successors. D'Ancona (1928) published a major treatise on leptocephali from the Red Sea. Within this, he included a summary of all the leptocephali that had been described previously and tried to assign them to a family. In the Fauna and Flora of the Gulf of Naples series, D'Ancona (1931) provided the first comprehensive survey of the leptocephali of the Mediterranean. Sparta, in a series of papers published from 1937 to 1942, described the larval development of several species of Mediterranean eels (see Castle, 1969c: 108, for a list of these). Most of these had been identified previously, but Sparta provided nearly complete developmental series. Aside from Italy, the most important work on leptocephali during the first half of the 20th century was done in Denmark and France. Johannes Schmidt and his group were interested mainly in Anguilla, but during their many expeditions they collected a host of leptocephali of all kinds. Schmidt himself identified the larval forms of Chlopsis bicolor (1912b) and Nessorhamphus ingolfianus (1930) and described several leptocephali that could not be identified. Jespersen (1942) described the leptocephali of the Indo-Pacific species of Anguilla. The principal French workers in this period were Roule and Bertin, whose careers overlapped in the 1920's. Roule began studying leptocephali about 1910, using material both from the Danish expeditions and from the Prince of Monaco's cruises. He was particularly interested in midwater eels and described the metamorphosis of Nemichthys (Roule, 1914a). He also described two distinct forms of notacanthiform leptocephali, although he was not aware of their identity at the time (Roule, 1911). In the 1920's he was joined by Bertin in a study of the midwater eels of the

1920-1922 Dana expeditions (Roule and Bertin, 1929). Bertin continued his studies of eels for many years, and in the 1930's he published on the cyematid and saccopharyngoid leptocephali of the Dana collections (Bertin, 1936c, 1937,1938). He also re-examined the specimens of Stromman and Kaup and provided the first myomere counts for them (Bertin, 1935a, 1936a,b). American and British ichthyologists paid relatively little attention to leptocephali during the first half of the 20th century, although some significant work did appear. Carman (1899) introduced a substitute name for Leptocephalus, Atopichthys, because the former was then being recognized as the senior synonym of Conger. Eigenmann and Kennedy (1901, 1902) described several leptocephali, including the larva of the American eel, Anguilla rostrata. Fowler described several species of Leptocephalus over a period of years without trying to identify them with adults. Regan (1916) described a few leptocephali from the Terra Nova Antarctic expedition. Beebe (1935b) and Beebe and Crane (1936,1937a,b) published on leptocephali of midwater eels from the Bermuda Oceanographic Expeditions; some of their work is very good, but other parts contain serious errors, particularly the section on Platuronides. During the 1940's and 1950's several papers were published on leptocephali from Indian waters. Among these were descriptions of the larvae of Uroconger lepturus (Nair, 1946; Nair and Mohamed, 1960c), Muraenesox cinereus and Thyrsoidea macrura (Nair, 1947), Congresox talabonoides (Nair and Mohamed, 1960a), and Congresox talabon (Nair and Mohamed, 1960b). In the 1960's the tempo of work on leptocephali began to accelerate, corresponding to an increased attention to the systematic relationships of eels in general. The most important worker at this time was P. H. J. Castle in New Zealand. He published several papers on leptocephali of Australasian waters, emphasizing family characteristics. In 1968 he visited Copenhagen, where he sorted the leptocephali of the Dana collections and made them available for more detailed work in the future. His Index and Bibliography of Eel

Leptocephali: Introduction

Larvae (Castle, 1969c) is an invaluable source of information on the nomenclature and literature of leptocephali. Blache, working in Pointe Noire and Dakar, West Africa, published extensively on the eels and eel larvae of the Gulf of Guinea. His work culminated in a major treatise on the leptocephali of that area (Blache, 1977). Orton wrote on the leptocephali of saccopharyngoids (1963), the nemichthyid genus Avocettina (1964a), and chlopsids (1964b). Eldred published a series of papers on leptocephali of western Atlantic eels and elopiforms. Other workers of note include Keller (1976) on the leptocephali of the Bermuda Ocean Acre, Fahay and Obenchain (1978) on ophichthid leptocephali from the U.S. east coast, and Leiby, who has published several studies on western Atlantic ophichthid leptocephali. D. G. Smith has published numerous papers on western Atlantic leptocephali, including the Chlopsidae (1969), Notacanthiformes (1970), ilyophine synaphobranchids (1974), and a guide to the family-level identification of leptocephali (1979). Smith and Castle collaborated on studies of Neoconger (1972) and the Nettastomatidae (1982). Several Japanese workers have been studying leptocephali, including O. Tabeta, M. Okiyama, and N. Mochioka. Nomenclature. Delage's (1886) demonstration that Leptocephalus morrisii was the larval form of Conger conger ushered in a period of confusion over the use of the name Leptocephalus. A uniform code of zoological nomenclature did not exist until 1905, but the principle of priority was generally accepted. Despite the fact that it upset more than a century of usage, some ichthyologists, led by Jordan, discarded Conger in favor of Leptocephalus. This left the larval forms without a name, and Garman (1899: 327) proposed the name Atopichthys to be used for these when their true identity was unknown. Hardly anyone but Garman ever used Atopichthys, however, and in practice Leptocephalus continued to be employed for larvae. In fact, almost no one outside the United States followed Jordan's lead in using Leptocephalus for the conger eel. The International Commission on Zoological

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Nomenclature exercised its relatively new powers in 1912 (Opinion 44) by officially recognizing Leptocephalus Gronow, 1763, as the valid name for the conger eel. No one seemed to pay much attention, though, and European workers continued to do just as they always had. A dual system of nomenclature existed, therefore, with Jordan and his followers using Leptocephalus for the conger eel and everyone else using it for larval eels of all description. Further confusion existed over the authorship of both Leptocephalus and Conger. Gronow (1763) did not use the binomial system consistently, and many felt his names should not be accepted. The next available author was Scopoli (1777), but Houttyn (1764) had previously used Conger in a sense that some interpreted as a genus. The Commission attacked the problem again in 1926 (Opinion 93). This time it established Conger Cuvier, 1817 (later changed to Conger Oken, 1817) as the valid name for conger eels, clearly eliminating that part of the controversy. It also seemed to approve the use of Leptocephalus Scopoli, 1777 (Gronow, 1763, was rejected for nomenclatural purposes), as a catch-all for larval eels. Although this confirmed established practice, it left a peculiarly untidy situation. How could Leptocephalus, a legal name originally applied to one discrete species, be officially sanctioned for use with animals that represented a whole spectrum of genera? In 1958 (Direction 87), the Commission finally suppressed Leptocephalus under Plenary Powers. In practice, Leptocephalus continued to be used until very recently to refer to leptocephali that could not be identified. The fact that the genus is invalid does not affect the validity of the species included in it. Arguments can be made both for and against this practice. On the one hand, it creates a dual system of nomenclature and assures that some names, either larval or adult, will have to be synonymized when the particular larvae become identified. In addition, some larval "species" are clearly complexes of more than one biological species. In this sense, naming leptocephali creates more confusion. On the other hand, there is an undeniable convenience in having a simple name by which to refer to those

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leptocephali that cannot be assigned to an existing species. A name like Leptocephalus inferomaculatus is more satisfying and more meaningful than something like "Congridae Genus A species A/' Workers today have largely stopped naming new species of Leptocephalus, and I have followed that practice here. General Morphology. Leptocephali are among the most distinctive of all larval fishes. They have an elongate, highly compressed body with a series of V- or W-shaped myomeres covering most of the lateral surface. The viscera are confined to a narrow strip along the ventral margin of the body. The head is small in comparison to the body (hence the name, leptocephalus = "slender head") and bears a series of slender, fang-like, forwardly directed teeth. Most of the interior of the body is filled with an acellular mucinous material bounded by a continuous layer of epithelial cells. This mucinous pouch is the most characteristic feature of the leptocephalus. It separates the viscera, the notochord, and the two sides of the body musculature from each other and gives form and rigidity to the body. The myomeres are thin, and the skin is only a few cell layers in thickness. Dorsal, anal, and pectoral fins are present in all leptocephali, although the pectoral is without rays until metamorphosis. In eel leptocephali, the dorsal and anal fins are long-based and continuous with a small, round caudal fin. Elopiform leptocephali have a large, forked caudal fin separate from the short-based dorsal and anal fin. In notacanthiform leptocephali there is no real caudal fin, but instead a single filament. Hypural plates are present in all leptocephali, even notacanthiforms, well before metamorphosis. Pelvic fins are present only in elopiform and notacanthiform leptocephali. The eyes and olfactory organs are well developed, and the portions of the brain associated with them are equally well developed. The teeth are distributed in a single series along the outer edge of the upper and lower jaws. At the tip of the upper jaw is a pair of small teeth, each growing from a small, separate bone. Whether these represent the premaxillae is a matter of dispute.

Leiby (1979b: 514) felt that they do not and cited Berry (1964: 378), who found a similar structure in larval Albula, a genus which also has true premaxillae. The structure in Albula, however, is unpaired and may not be the same. More study is needed. The anteriormost tooth on the maxilla is usually larger than the rest and directed more anteriorly. The remaining maxillary teeth generally come in two distinct sizes, the anterior ones being significantly larger than the posterior ones. The mandibular teeth are also divided into a larger anterior and a smaller posterior series. The gut is a simple tube, although it is sometimes bent and looped in complex ways. It consists of an anterior esophagus and a posterior intestine. The stomach is a rudimentary diverticulum at the point where the esophagus and the intestine meet. The liver and gall bladder are located near the same point, although the liver can sometimes be fairly extensive and divided into more than one lobe. The kidney (nephros) is a linear structure lying along the top of the gut. In some leptocephali it is a simple tube, but in others it is thickened at various points. The heart is located beneath the anterior end of the esophagus and in front of the pectoral fin. Gill arches are present, but filaments do not appear until later in development (though before metamorphosis). The notochord runs through the middle of the body. The spinal cord lies directly above it and the dorsal aorta directly below. These three structures are surrounded by the mucinous pouch and separated from it by a layer of epithelial cells. Several vertical blood vessels extend between the dorsal aorta and the viscera; the posteriormost one enters the posterior end of the kidney. Living leptocephali are completely transparent; in an aquarium they are practically invisible except for the eyes. After death, they become whitish. Hemoglobin is not present before metamorphosis, and the only pigment, is melanin present in the choroid of the eye and in discrete melanophores distributed in characteristic patterns on the head and body. A few leptocephali lack melanophores, but most have at least some. One of the most striking features of leptoceph-

Leptocephali: Introduction all is their large size. Lengths of 50-100 mm are common, and some forms grow much larger. The record is 1800 mm for a notacanthiform leptocephalus (Nielsen and Larsen, 1970). Much of the size is accounted for by the mucinous pouch. The effect is similar to inflating a balloon; the myomeres of the two sides are forced apart, becoming thinner and thinner, and the dorsal and ventral margins are pushed away from the notochord. At metamorphosis, the leptocephalus shrinks as the mucinous filler is lost. Development and Metamorphosis. Eel eggs tend to be relatively large, up to 3-4 mm in some cases (Eldred, 1969b), with a large perivitelline space. Late-stage embryos are usually recognizable as leptocephali even while still in the egg. The yolk sac remains for a few days after hatching. Leiby (1979a: 332) has divided the premetamorphic development of leptocephali into two stages, which he calls engyodontic and euryodontic. The engyodontic stage is "characterized by a few needlelike teeth, each tooth shorter than the one anterior to it; lower jaw equal to or longer than upper; nasal capsule unformed; fin-fold not yet differentiating; hypurals not forming; ratio of head and preanal lengths to total length high as compared to other stages" (Leiby, 1979a: 332). The euryodontic stage is defined as commencing "with shedding of needle-like teeth in anterior end of lower jaw, shedding proceeds posteriorly on lower jaw then anteriorly on upper jaw, engyodontic teeth replaced concurrently by three series of shorter, broad-based teeth in both upper and lower jaws; lower jaw becoming shorter than upper; head length as percent of total length decreasing; hypural formation and fin differentiation" (Leiby, 1979a: 332). This division may correspond roughly to the preflexion-postflexion transition in other fishes. During the course of the euryodontic stage, changes continue to take place, but they are relatively minor. The body usually becomes less deep, the preanal length decreases, and the head becomes smaller relative to the body. The median fins become better developed, gill filaments appear, the teeth become smaller compared to the head, and the nostrils begin to form. The

661

maximum size reached by a leptocephalus is usually fairly constant within a species. There is evidence that at least some species can postpone metamorphosis if they do not find themselves in a suitable location. Nevertheless, most species seem to have a characteristic length of larval life. Metamorphosis in fishes with a leptocephalus larva is a profound process, probably more extreme than in any other group of fishes. It is not instantaneous, but the amount of change occurring in a relatively short time far exceeds that at any other stage of life. Rasquin (1955: 78) found that specimens of Albula collected at Bimini completed their metamorphosis in about 8-15 days. My own observations of Elops saurus from Galveston Island, Texas, showed that specimens went from largely leptocephalus-like in appearance to essentially juvenile in approximately 3 weeks. In both cases, the leptocephali had already begun metamorphosis when collected, but the figures give a good idea of the rate of change. The head usually begins to metamorphose while the body is still deep and compressed. The larval teeth are lost, presumably by resorption, and anlagen of the definitive teeth begin to develop. The skin thickens and forms the characteristic patterns of the lips and snout. The nostrils move to their final position, and the pores of the lateralis system begin to form. The digestive tract begins a radical reconstruction. The anus often moves forward as the intestine thickens, and the stomach enlarges to form a blind sac of variable length. The mucinous pouch contracts as the filler is lost, again presumably by resorption. The two sides of the musculature approach each other and thicken, meeting along the midline above and below the notochord. The animal becomes rounder in cross section, and its length decreases significantly. The skin thickens and lateral-line pores form. Those species that lack the pectoral fin as adults lose it at metamorphosis. The definitive pigmentation is usually one of the last adult features to appear. Individuals that have assumed the juvenile form but have not yet developed pigment are called glass eels. At this point they may still be pelagic, but they soon settle out and take up the way of life of the adult.

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Midwater eels, of course, stay in open water, but they descend to the depths they will inhabit as adults. When metamorphosis is complete, the young eel starts to grow again. Whether metamorphosis is triggered by some environmental stimulus or occurs spontaneously at a certain age or size is unknown. The concentration of metamorphic Anguilla over the edge of the continental slope suggests that they are responding to some characteristic of the water there. In other cases, however, metamorphic specimens have been found far from suitable adult habitat. Biology. The leptocephalus is a true oceanic larva. All fishes that have a leptocephalus larva, even those that live in estuaries or fresh water most of their lives, spawn offshore in clear, warm, saline water. Osmoregulatory mechanisms are barely functional in young leptocephali, and not until late in development are they able to cope with varying or reduced salinities. Beyond this, virtually nothing is known about the biology of leptocephali. This is largely due to the difficulty in capturing and maintaining them alive. The skin of the leptocephalus is extremely thin, no more than two or three cell layers in thickness. The epidermis is loosely attached to the dermis and is easily damaged. The only way leptocephali can be consistently collected is in a plankton or midwater net, and the agitation is almost always enough to abrade some of the epidermis. Once this happens, the leptocephalus invariably dies. There has been much speculation about the trophic relationships of leptocephali, but hard evidence is still absent. No recognizable food organisms have ever been found in the gut of a premetamorphic leptocephalus. Absorption of dissolved organic material has been suggested (see Hulet and Robins, p. 671), but experiments so far have been inconclusive. Pfeiler (1986) proposed a mechanism that might accomplish this. Premetamorphic leptocephali contain relatively large amounts of sulfated glycosaminoglycans (GAG), which facilitate the uptake of water and salt. A sodium-dependent process for assimilating dissolved organic material, if such exists in

leptocephali (it has been demonstrated in some invertebrates), would be enhanced by the retention of salt. During metamorphosis, the GAG are broken down and used for nutrition. With the loss of GAG, water and salt are also unloaded. When metamorphosis is complete, the animal begins to feed normally. Pfeiler's hypothesis is attractive because it explains several peculiar features of leptocephali (mucinous pouch, high water and salt content, and the loss of all these at metamorphosis) in meaningful functional terms. It remains to be demonstrated experimentally, however. A glance at a leptocephalus shows that it depends largely on its eyes and nose to sense its environment. The eyes and nasal organ are exceptionally well developed, as are the parts of the brain associated with them. A well developed chemical sense may be important in telling the leptocephalus when it has reached a suitable area for metamorphosis. In this context it is interesting to note that leptocephali of the Serrivomeridae and Nemichthyidae, which remain oceanic after metamorphosis and hence do not have to locate coastal water, have distinctly smaller nasal organs than those of other families. The eyes may serve primarily for orientation and avoidance of predators. Since we do not know what leptocephali eat, we cannot say whether the eyes serve in feeding behavior as well. The lateralis system appears to be absent except for a small tunnel on the midline of the snout opening through a pore on each side. Hulet (1978:129) felt that this was part of the rostral commissure. Leptocephali appear to move up and down in the water column from night to day. They are most commonly collected in the upper 100 m at night, but tows taken during daylight at the same depths usually collect very few. Part of this may be due to net avoidance, but the leptocephali probably disperse downward in the daytime. When leptocephali are captured alive, they are seen to swim vigorously in the aquarium, with equal proficiency backward or forward. They seem to be slightly negatively buoyant; they have no gas bladder, so they must control their depth by swimming.

Leptocephali: Introduction The distribution patterns of certain eels, for example the Atlantic Anguilla, suggests that larval migration may not be entirely passive. Mechanisms for directing large-scale movements are, at this point, quite unknown. By seeking particular depths, leptocephali may be able to find currents that will take them where they "want" to go. Alternatively, by swimming persistently in a certain direction they may be able to cover considerable distances on their own. There is some evidence that leptocephali of Anguilla rostrata may cross the Gulf Stream in this manner (see family Anguillidae, p. 39). A great many questions remain to be answered about leptocephali. The problems involved in studying them in their natural habitat and the difficulty of keeping them alive in captivity assure that many of these questions will long resist solution. Identification of Leptocephali. Within the basic constraints of their design, leptocephali vary widely in form. Consequently, we have a rich supply of characters to use in identifying these larvae. The three orders (I include the Saccopharyngiformes with the Anguilliformes here) are easily distinguished from each other by the form of the dorsal and caudal fins and by the presence of pelvic fins in the Elopiformes (I use this term in the traditional sense, whether or not it is phylogenetically accurate, for the Elopidae, Megalopidae, and Albulidae) and Notacanthiformes. The Elopiformes and Notacanthiformes are both small groups, and their leptocephali show relatively little variation. Elopiform leptocephali are easily identified by the relative position of the dorsal and anal fins, pigmentation, shape of the head, and number of myomeres. Several distinct kinds of notacanthiform leptocephali can be distinguished, mainly by the shape of the head and eye, but none can yet be identified with a specific adult. The Anguilliformes (including Saccopharyngiformes) is by far the largest elopomorph order, and most of the leptocephali encountered are eel larvae. Anguilliform leptocephali show great variety in almost all characters. The body may be short and deep, as in Cyema, long and slender,

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as in Nemichthys, or almost any condition in between. The form of the tail varies from slender and attenuate to broadly rounded. The dorsal fin may begin anywhere from shortly behind the head to just before the caudal fin. The anal fin usually begins immediately behind the anus, but in at least two genera of muraenids the anal-fin origin is distant from the anus. The pectoral fin is usually well developed, even in those species that lack it as adults, but muraenids have a greatly reduced pectoral fin even in the leptocephalus. The gut may be nearly as long as the body (in a few cases it actually extends freely beyond the end of the body), or it may be as short as onefourth of the SL. In some leptocephali the gut is a simple, straight tube without modifications. In others, however, the gut may have a variety of swellings, loops, or switchbacks. The liver may be a single, compact lobe or there may be two or three lobes. The head varies from long to short, and the snout may be acute or bluntly rounded. The eye is usually round or slightly elliptical, but synaphobranchids have a telescopic eye. Pigmentation varies widely among leptocephali. The number of myomeres varies from about 70 in Cyema to well over 300 in Nemichthys; most leptocephali have between 100 and 200. Families, genera, and groups of genera or species are characterized by combinations of these features. At the species level, the number of myomeres is the most important character. Each species has a characteristic number of myomeres, generally varying within a range of about 10. The distribution is normal, with the number of specimens showing each value declining on either side of the mean. In addition to total myomeres, preanal and predorsal myomeres are important characters, but they are not available in very young leptocephali. The position of the posterior end of the kidney and the posterior renal artery are also important characters. These are counted according to the myomere to which they are closest. Dorsal- and anal-fin rays are sometimes useful characters, but they are fully developed only in relatively advanced growth stages. The above characters distinguish one lepto-

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Fishes of the Western North Atlantic, Part 9

cephalus from another, but by themselves they cannot identify the leptocephalus with an adult. The only character consistently carried through metamorphosis is the number of myomeres, which is equivalent to the number of vertebrae in the adult. Since there are likely to be more than one species of eel in an area with similar vertebral counts, it is necessary to narrow the identification down to family or genus before attempting to match numbers of myomeres with vertebrae. Two things are necessary for this: first, the presence of metamorphic specimens, which combine characters of the leptocephalus and the adult; and second, some grasp of the systematic relationships of eels. When the leptocephalus of a particular species has been identified through metamorphic specimens, it is then possible to identify related species by inference, even if metamorphic specimens are not available. This process has allowed us to build a framework upon which most leptocephali can now be identified fairly easily, at least to the family level. A few other characters are sometimes carried through metamorphosis. Pigmentation often persists for some time in the juvenile. Although it eventually disappears, while it lasts it can provide a good link between leptocephalus and adult. The posterior end of the kidney is related, at least approximately, to the position of the first caudal vertebra in the adult. Since the last vertical blood vessel passing from the aorta to the viscera enters the posterior end of the kidney, this character, too, is related to first caudal vertebra. Generally speaking, the smaller the leptocephalus the more difficult it is to identify. Many of the important distinguishing characters develop with growth and may not be present in very young specimens. Methods. Figure 708 shows a typical anguilliform leptocephalus with some of the principal characters and commonly used counts and measurements. Total length (TL) is measured from the tip of the snout to the end of the caudal fin. Standard length (SL) is measured from the tip of the snout to the end of the hypurals; this is a more convenient measurement than total length,

because the hypurals are much easier to see than the end of the caudal fin, which is often damaged anyway. In young specimens in which the hypurals have not developed, SL is measured to the posterior end of the notochord; this might more properly be called notochord length (NL), as it is in more normal fishes, but in eels the caudal structure is so small that the difference is not very noticeable. Preanal and predorsal length are measured from the tip of the snout to the origin of the anal fin and dorsal fin, respectively. Head length (HL) is measured from the tip of the snout to the anterior margin of the pectoral-fin base. Body depth is measured at its greatest point; usually this is near midlength, but sometimes it is distinctly behind that point. All myomeres are counted, including the few anteriormost ones that do not continue below the midline. The posteriormost myomeres are sometimes difficult to count, especially in small specimens and in those species with an attenuate tail; in these cases it is sometimes easier to count the spinal ganglia, which are related to the myomeres on a one-to-one basis. Preanal and predorsal myomeres are counted back to and including the one directly over the anus and under the dorsal-fin origin, measured at the midline. Nephric myomeres are those before the point directly above the posterior end of the kidney, measured at the midline and counted inclusively. The position of the last vertical blood vessel (LVBV) is expressed as the myomere at which it joins the aorta, again measured at the midline. As the LVBV usually ascends obliquely, there are slightly more LVBV than nephric myomeres. Prehepatic myomeres are those back to and including the one directly over the anterior end of the liver, measured at the midline. Fixation and Preservation. Until the chemistry of fixation and preservation is better understood, it will probably be impossible to specify a foolproof procedure for fixing and preserving leptocephali. In examining many thousands of specimens in many collections all over the world, I have seen a wide variety in the state of preservation. The condition of specimens is often quite

Leptocephali: Introduction

standard

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L0OQth

FIGURE 708. A leptocephalus showing anatomical features and principal measurements.

independent of age. Properly preserved specimens will remain useful for many years; improper preservation wil render them worthless in a fraction of that time. The question, which has not yet been satisfactorily answered, is what constitutes proper fixation and preservation. Initial fixation at sea almost always involves a solution of formaldehyde. Whole plankton samples are fixed, and the leptocephali are removed later. In my experience, the fixative has been a 5 or 10% formalin solution in seawater, either buffered or unbuffered. The sample remains in this solution until it is sorted later in the laboratory. This procedure obviously lacks the kind of precise standardization we should ideally prefer, but in fact precise standards are not available. Another uncertainty involves the fact that most of the specimens are already dead before they are fixed. In warm climates (and leptocephali are found mainly in the tropics) a delicate organism such as a leptocephalus may already have begun to decompose. Problems may thus exist even before the specimen reaches the laboratory. Steedman (1976) proposed a formula specifically for fixing leptocephali, consisting of formalin, pro-

pylene glycol, and alum. I tried this on one of the MBI cruises (see p. 666) and got unsatisfactory results. The specimens became white and opaque and rather brittle. The standard long-term preservative for leptocephali as well as other larval fishes has commonly been a 4 or 5% formalin solution, usually buffered with borax, marble chips, or something similar. Based on what I have seen, this gives wildly uneven results. Some specimens seem perfectly all right after years in formalin. Others begin to deteriorate relatively quickly. One of the most frequently seen conditions is a clearing effect, wherein the specimen becomes soft and flabby and increasingly transparent, the various body parts losing their refractive contrast. When removed from the fluid and placed on a dish, the specimen collapses into a heap of jelly. Pigment is lost and the flesh takes on a granular consistency. One of the first signs of this process is a fading of the pigment; the eye turns from black to brown. Another common problem is a swelling of the body. The two sides of the body become separated from each other and the specimen swells up like a balloon. When the skin is

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Fishes of the Western North Atlantic, Part 9

punctured or split, the viscous fluid inside escapes. Since the sides of the body are no longer connected, the specimen loses its shape and requires careful manipulation to get right and left sides lined up again. The cause of these problems is largely unknown. The history of a specimen's fixation and preservation is seldom available, so it is difficult to know where the problem originated. The pH may be a problem, and also the buffering agent used. Hexamine is particularly bad, and even sodium borate may be inadvisable (Lavenberg et al., 1984: 59). Alcohol largely eliminates these problems. In particular, I have never seen the clearing effect in alcohol-preserved specimens. The main problem with alcohol is a discoloration and sometimes a tendency for wrinkles to be set in. These are relatively minor, however, and I have never seen an alcohol-preserved specimen that has deteriorated to the point that formalin-held specimens sometimes do. The Dana collections were originally kept in a solution of ethanol, formalin, and glycerine. When Castle sorted them in the 1960's, he used straight 70% ethanol, deeming the glycerine unnecessary (Castle, pers. comm.). Today the Dana specimens are still in remarkably good condition, considering that they are more than half a century old. The UMML specimens were stored in 45% isopropanol, and after some 20 years they are fairly well preserved. The MBI specimens were preserved in 5% formalin in deionized water. After some 10 years, they were still in good condition. They have recently been transferred to ethanol and are still in good condition. Much work obviously remains to be done on the whole question of fixation and preservation. Formalin will probably continue to be the fixative of choice; no one seems to have found anything better. Specimens should be fixed as quickly as possible after they are brought up in the net. At this point, I would recommend 75% ethanol as a permanent preservative for leptocephali. At the very least, it is more forgiving than formalin, and it is certainly more pleasant to work with. I must note, however, that I tried ethanol on some of the early MBI specimens,

with poor results. The specimens became opaque and relatively stiff and difficult to work with. More recently, some formalin-fixed specimens at the MCZ were transferred to ethanol with equally unsatisfactory results. The mucinous filler became discolored and granular in appearance and texture. Many other specimens, however, have been transferred to ethanol with no problems. Study Material The material used in these studies has come from a variety of sources. The most important in terms of quantity are MBI, UMML, ZMUC, and ISH Anton Dohrn. Others of note include MCZ, FDNR, IRCZM, VIMS, and URL The MBI collections were made in the Yucatan Channel and the western Gulf of Mexico and were designed specifically to catch leptocephali. The purpose was to sample the area in each of the four seasons to determine what leptocephali were present and to gain some idea of seasonal and spatial distribution. To this end four main cruises were carried out on the R/V Gillis and R/V Iselin, both operated by the University of Miami. The dates were 8-19 November 1975,1023 April 1976,13 February-2 March 1977, and 20 July-5 August 1977. In addition two shorter cruises were conducted, off Cozumel in August, 1975 and off Veracruz in August, 1976, both using the MBI's small research vessel, the Erin LeddyJones. The stations (Fig. 709) were selected to give the widest possible coverage of the western Gulf of Mexico in the time available. The Yucatan Channel stations were included to compare the leptocephali of the Gulf with those of the adjacent Caribbean. Most of the stations were located between the 100- and 1000-fathom curves (180 and 1800 m), but one station over the shallow Campeche Bank was included for comparison. An open, conical plankton net with a mouth diameter of 2 meters and a length of 10 meters was used. A mesh size of 570 microns was used most of the time, but on some occasions a 360micron mesh was used instead. The larger mesh was more suitable as it did not clog as readily. The ring was attached to the trawl wire by a five-point bridle, and the whole apparatus was weighted with a 50-kg depressor. A time-depth recorder was used on all tows.

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Leptocephali: Introduction 95°

30'-

95*

00'

95*

85Q

85°

Summer

Spring 30*

90°

30" -

15*-

10*

20°-

FIGURE 709. Location of stations occupied during MBI cruises in the Gulf of Mexico and Yucatan Channel, 19751977.

All collections were made at night. After some trial and error on the early cruises, it was determined that the greatest number of leptocephali were collected at a depth of about 50 m. After that a standard procedure was established whereby five tows were made at each station, three with 150 m of wire out (mwo) and one each with 75 mwo and 300 mwo. With a rough wireto-depth ratio of three to one, that put three of the tows in the zone of greatest abundance, while the other tows sampled the shallower and deeper layers. Although some contamination occurred on the way up and down with the open net, occurrence of any species consistently above or

below the 50-m level should be detected by the shallow and deep tows. Occasionally, when the ship arrived on station before nightfall, a deep tow with more than 300 mwo would be made. Towing speed was kept as close to two knots as possible. This minimized mechanical damage to the specimens in the net while providing enough speed to capture the large and active leptocephali. The duration of each tow was normally 15 minutes at depth, but this varied according to the abundance of plankton. In extreme cases, tows as short as 5 minutes or as long as an hour were necessary. Most of the MBI specimens are now deposited

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at the ANSP. Those listed without a museum acronym cannot be located. The UMML collections were made over a period of years, mainly the 1960's and early 1970% by several vessels, principally the R/V Gerda, Pillsbury, and Tursiops. Most of the specimens were taken in 6- or 10-foot (1.8 or 3 m) IsaacsKidd Midwater Trawls (IKMT) or 2-m plankton nets. Part of the Congridae and the Muraenidae are now deposited at the ANSP, the remainder are still at UMML. The ZMUC collections are those taken by the Dana and other Danish vessels. This is probably the largest collection of leptocephali in existence; in terms of quantity and area of coverage, it may never be equalled. Thanks to Castle's efforts, the collection is now sorted and arranged on the shelves by family, but only a fraction of the material has actually been studied. Schmidt and his colleagues were interested mainly in Anguilla. The Nemichthyidae were studied by Roule and Bertin (1929), the Cyematidae and Saccopharyngoidei by Bertin (1937, 1938), the Synaphobranchinae by Bruun (1937), and the Serrivomeridae by Bauchot (1959). Castle worked on the Derichthyidae (1970b) and Moringua (1979), and

Smith and Castle did Neoconger (1972), the Nettastomatidae (1982) and Ilyophinae (unpubl.) Blache examined many of the ophichthids but did not publish on them. The Ophichthidae, Congridae, and Muraenidae are so voluminous that they may never be thoroughly studied. Descriptions of the cruises, scientific objectives, methods, and station data may be found in Schmidt (1929,1931a) and Carlsberg Foundation (1934). The Anton Dohrn material was collected on a cruise to the Sargasso Sea in March-April, 1979. The specimens reported on here were examined during preliminary sorting on board; I rely on counts, measurements, and notes made at the time. With a handful of exceptions, these specimens were returned to the ISH for final sorting and deposit. Details and station data for this cruise are provided by Tesch (1982). The MCZ currently houses the larval fishes, including leptocephali, collected by the vessels of the Woods Hole Oceanographic Institution. This is now one of the largest collections of leptocephali anywhere, but it is still incompletely sorted. New material is being added constantly.

KEY TO THE ORDERS OF LEPTOCEPHALI la. Caudal fin large and forked; myomeres fewer than 100 Elopiformes, p. 961 Ib. Caudal fin small and round or absent; myomeres usually more than 100 2 2a. Caudal fin small and round, continuous with dorsal and anal fins Anguilliformes (including Saccopharyngiformes), p. 679 2b. Caudal fin absent, instead a single filament; dorsal fin short, located anteriorly Notacanthiformes, p. 955

The Evolutionary Significance of the Leptocephalus Larva W I L L I A M H. HULET and C. R I C H A R D ROBINS cephalaspidomorph fishes is unknown and will no doubt remain so. Fishes of the superorder Elopomorpha share one important feature to the exclusion of all other fishes, the possession of a leptocephalus larva. It was on the basis of this character that Greenwood et al. (1966) composed the Elopomorpha, which was placed as the sole group in their major, unnamed "Division I." They later (Greenwood et al., 1967) assigned the cohort name Taeniopaedia to this division, elevating, in essence, their assessment of the distinctiveness of this group, a move termed naive by Hubbs (1967). An understanding of the structure, function, and the evolutionary significance of the leptocephalus is vital, therefore, to any testing of the integrity of the Elopomorpha, and in reexamining the relationships of the living orders and families now placed in this superorder. The development and metamorphosis of the eel leptocephalus is not a sharply bounded series of events. Different systems appear at different times, and do not necessarily occur at the same stage in different groups of eels. Terms such as premetamorphic and metamorphic or engyodontic and euryodontic are related to changes in growth rather than to any one developmental event. Structure of the Leptocephalus. Hulet (1978) described in detail the structure of the leptocephalus of the congrid Ariosoma balearicum (Delaroche). The summary which follows is also based on examination of the leptocephali of many kinds of eels and other elopomorph fishes, representing all major lineages. Vision and olfaction stand out as the only two functions represented by

Acknowledgments. We thank Margarita V, Ackerson for mastering the technique of the nanoliter osmometer and for making hundreds of osmolality measurements. She also provided the scanning electron micrographs. We are grateful to David G. Smith for his expert assistance in identifying leptocephali. Assistance in statistical analysis was provided first by the late Raymond F. Hixon, and then, in the final stages, by Behzad Mahmoudi. Collections of live leptocephali were made when one of us (W.H.H.) was a member of the Marine Biomedical Institute, University of Texas Medical Branch at Galveston. William D. Willis, Jr., Director of the Institute, was most helpful in encouraging this work and in providing financial support for its completion. Grant support was received from the National Science Foundation, NSF BMS 75-08675, W. H. Hulet and D. G. Smith, co-principal investigators. Support for one of us (C.R.R.) was provided by the Maytag Chair of Ichthyology. We thank Catherine H. Robins for review of the manuscript and for many discussions of the problems set forth herein, and M. M. Leiby, P. L. Lutz, N. B. Marshall, and D. G. Smith for helpful comments concerning the manuscript.

Introduction. Larval development of the fishlike vertebrates is remarkably uniform, especially so for actinopterygian fishes. Some families of marine teleosts may have an extra life history stage, which, in certain bathypelagic fishes (e.g., Giganturidae, Gibberichthyidae), may be so bizarre and so unlike the juvenile that one may properly speak of a metamorphosis as occurring between it and the juvenile stage. This stage, however, is clearly postlarval in development, and was named the prejuvenile stage by Hubbs (1958) and subsequent authors. Two groups of fishes have a distinctive longlived larval stage. All lampreys (subclass Petromyzontes, class Cephalaspidomorpha) have an ammocoete larva. Whether it was common to all 669

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Fishes of the Western North Atlantic, Part 9

FIGURE 710. Scanning electron micrographs of a premetamorphic leptocephalus of Ariosoma balearicum (a = rostral commissure, b = anterior nostril, c = posterior nostril, d = eye). Bar measures in microns.

well-developed organ systems in the leptocephalus. Before the onset of metamorphosis, most structures, but especially the gut, skin, gills, and kidney, appear to be in varying stages of embryological development and bear little resemblance to these same tissues and organs after metamorphosis. A small, thin, laterally compressed head gives the leptocephalus its name. In bright light, only the small portion of the pigmented retina visible through the lens betrays the position of an actively swimming leptocephalus. The rest of the body is transparent. Although well endowed with sharp-pointed teeth, they point forward and interdigitate in such a fashion that the mouth cannot be closed completely. Their function has never been explained satisfactorily. We discount suggestions that they have to do with capturing prey or that they serve as a "cut-water7' in swimming. In our view, the teeth best serve as a screen permitting only sea water and microscopic plankton to enter the oropharyngeal cavity. Hulet (1978: pi. 20) showed that the teeth project from the dermal bone, are without sockets, and that the pulp cavity extends to the tip of the calcified matrix of each tooth. This tissue is well equipped for resorption, and all of these peculiar teeth of the early leptocephalus seem to be resorbed during the process of metamorphosis, thus serving as a bank for calcium and other salts needed for the

formation of the definitive structures of the juvenile. We find no evidence of these teeth being shed during metamorphosis. During the expulsion of water from the branchial basket, the oral cavity is sealed in front by a soft-tissue velum that hangs vertically from the rostrum and covers the inner surface of the jaw. There is a welldeveloped rostral commissure through the ethmoid complex (Fig. 710). Except for the anterior, paired, mandibular hemibranch, the branchial arches do not bear gill filaments, although their circulatory system is intact. The eye is the sole organ to receive oxygenated blood directly from the functioning hemibranch. As noted by Hulet (1978), leptocephali are unique among the teleostome fishes in possessing a functional mandibular hemibranch. Although the major components of a closed circulatory system are in place (see Hulet, 1978: figs 67-68), no erythrocytes or other cells with iron-containing pigment are present before onset of metamorphosis. We have not yet found evidence of the presence of a choroid gland in the eye of the leptocephalus. In the premetamorphic leptocephalus, the gut is non-functioning, and lacks a complete lumen. See the section on nutrition (below). Delayed maturation of the leptocephalus kidney is as impressive as the embryonic state of the gut and gills. No glomeruli are present. The

Leptocephali: Evolutionary Significance pronephros is represented by two archinephric ducts that begin as blind tubules, extend caudally, and drain a collection of aglomerular mesonephric tubules before terminating as a single urinary pore. An avascular mucinous pouch envelops the nerve cord, notochord, and dorsal aorta. The somatic myomeres of the two sides of the body are kept some distance apart by this collection of mucus. This material, mostly acid mucopolysaccharides and neutral fats, is resorbed during metamorphosis as the leptocephalus shrinks in size and the organ systems of the body develop. Rasquin (1955) and Pfeiler (1984a), with regard to the bonefish (Albula), also concluded that the function of the mucinous pouch was as a food reservoir. None of the materials stored in the leptocephalus appear to be lost during metamorphosis. Pfeiler (1984b) concluded that the glycosaminoglycan fraction played an important nutritional role in the metamorphic process. Evidence of food organisms in the gut does not appear until late in metamorphosis, after the head has assumed the characteristics of a juvenile eel and the gut has opened. The skin over most of the leptocephalus is extremely thin and easily damaged. The outer surface consists of flat epithelial cells with abundant filaments that project into the sea water. Secretory epidermal cells are entirely absent. Nutrition of the Premetamorphic Leptocephalus. Some nutrition must come from dissolved organic material absorbed by the surface epithelial cells of the skin and pharynx. Nutrition may also be obtained from microscopic particulate organic material, microbacteria, and other microscopic organisms trapped in and ingested by the cytoplasmic extensions of the tall columnar cells found in many parts of the oropharyngeal cavity (see Hulet, 1978: 129; they are evident, but not labelled, on fig. 66). According to Pomeroy (1974) and Pace et al. (1984), small free-living bacteria, 0.2-0.3 microns, occur in quantities of 105-106 per ml of sea water. Azam et al. (1983: 260-261) have questioned whether these microorganisms represent an organic link or organic sink. If they are utilized directly by such abundant animals as the

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leptocephali, they may be a very important link in energy transfer. Pace et al. (1984: table 5) also noted that bacterial production in the water column equalled that of zooplankton production. Particulate organic matter also may provide an important source of food for the leptocephalus. We cannot discount the possibility that a ctenophore, salp, or some other jelly-like organism could be caught in the jaws of a leptocephalus but we find no evidence for it. Cytoplasmic and extra-cellular fluids from the injured animal would be absorbed by the same mechanisms as used to take in dissolved organic material from the sea water. It seems most likely that the source of food for the growing, premetamorphic leptocephalus, is dissolved organic material, microscopic particulate organic material, or free-living microorganisms, or some combination of them. Origin and Function of the Leptocephalus. So many specialized features (see above) are shared by the leptocephalus larvae of all elopomorph groups that there is little question that this stage developed but once in the history of fishes. But why did it evolve? Impressed by the physical appearance of the leptocephali, Hulet et al. (1972) studied their electrolyte composition and concluded that, apart from the hagfishes, the premetamorphic leptocephali are more in ionic equilibrium with sea water than any other fishes. This observation was further supported by values for tissue fluid osmolality that exceeded 700 milliosmoles per kg of water (Hulet, 1978). The high osmolality for extracellular fluid in leptocephali is due principally to sodium chloride (Hulet et al., 1972) and the total ionic content calculated solely from Na plus Cl exceeds, except for the hagfishes, all other fish groups as reported by Lutz (1975). The earliest of vertebrate ancestors probably had their origin in the sea and the hagfishes, which are known only from marine waters, have retained a primitive system of ionic and osmotic equilibrium exhibited by such protovertebrates as the Cephalochordata. Smith (1936) strongly opposed a marine ancestry for the hagfishes on the basis of their large glomeruli which he argued could have developed only in fresh waters.

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Fishes of the Western North Atlantic, Part 9

It is more likely, however, that, like marine invertebrates (Hendrix et al., 1981) with closed circulatory systems, the Paleozoic ancestors of hagfishes developed ultrafiltration of the blood as a means for controlling the volume and composition of body fluids. Even with the capacity to filter and excrete a copious volume of urine, hagfishes never achieved the capability of excreting a dilute urine. Recent experiments (Alt et al., 1981) with single nephrons of Myxine glutinosa show that urine flow equals glomerular filtration rate and that sodium concentration in the urine is equal to or higher than the plasma. Hagfishes do not venture into oligohaline waters and survive for only a matter of hours when placed in 80% sea water. Although different in ionic composition, the total osmotic concentration of body fluids in hagfishes is isosmotic with sea water and is not particularly different from their invertebrate companions. Glomerular filtration alone, no matter how good, was insufficient for the invasion of continental freshwater rivers and lakes by ancestral vertebrates. Under these circumstances the presence of glomeruli, by themselves, is not persuasive with regard to a freshwater ancestry of hagfishes. Life in fresh water required a kidney whose tubular function was capable of absorbing sodium chloride from the glomerular filtrate against a concentration gradient. Any excess of water that had diffused into the organism was excreted as a dilute urine. The archinephric ducts of hagfishes are incapable of this function and excrete urine which is isosmotic with the plasma. Among the living fishes, the cephalaspidomorph lampreys are the first to have tubules (mesonephric) capable of extracting solute from the glomerular filtrate in order to produce a dilute urine. A copious flow of dilute urine provides renal control of both volume and composition, and assures constancy of the aqueous internal environment. An excretory system with these features was a basic requirement for Lower Devonian fishes to flourish in fresh water. New designs had to be developed for successful invasion of the sea. Two common designs are immediately apparent. One is for the adults and juveniles to exploit

the rich estuarine and coastal waters for feeding, but returning always to fresh water to spawn. This anadromous habit is found in such disparate groups as the lampreys (Petromyzontes), sturgeons (Acipenseriformes, an order of chondrostean actinopterygians), and trouts (Salmoniformes, an order of teleost actinopterygians). The system involves no adaptation of larval stages but juveniles are adapted to the osmotic stress of sea water. Glomerular filtration decreases precipitously, the renal tubules secrete divalent ions, and the "chloride cells" of the gills reverse the direction of sodium transport and actively remove salt from the blood plasma and excrete it into the ambient sea water. But this invasion by lampreys and other fishes was only a partial success in the sense that only part of the life cycle was spent in the sea. A return to fresh water for spawning is necessary. Eggs and hatchlings of these fishes are quickly killed by exsiccation when placed in* sea water. A second and very successful pathway is by the use of high concentrations of urea, trimethylamine oxide, and other nontoxic nitrogenous products in the blood to maintain serum osmolality at approximately that of sea water, thus equalizing osmotic pressures between the body fluids and the marine environment. The urea arises in a degrading sequence from an ornithine cycle. This pathway permits completion of the life cycle in the sea since it is coupled with the laying of large eggs enclosed in a keratin shell (all Holocephali, many Elasmobranchii) or the retention of the egg in the mother with a viviparous or ovoviviparous habit (many Elasmobranchii, Latimeria). It is used by the chimaeras, Holocephali, and sharks, elasmobranchii (the two living subclasses of the Elasmobranchiomorphi), and presumably by their coccostean ancestors. It is also used by Latimeria (Pickford and Grant, 1967; Brown and Brown, 1967; Lutz and Robertson, 1971), the only living marine Sarcopterygian. This urea-ornithine cycle is also found in the freshwater sarcopterygians (Dipnoa) where urea is retained as a metabolic end product in Protopterus and Lepidosiren during times of drought at which time these fishes are aestivat-

673

Leptocephali: Evolutionary Significance

TABLE 77. Blood osmotic concentration in premetamorphic and metamorphosing leptocephali of the congrid eel Ariosoma balearicum (VP = vapor pressure osmometer, FP = freezing point depression).

Larval stage

Number of larvae (n)

Premetamorphic Metamorphosing Premetamorphic

19 19 39

Premetamorphic

12

Standard length (mm) 163 ± S.D. 24.8 124 ±S.D. 7.90 141 (range = 95-181) 167 (range = 75-220)

Osmotic concentration (mOsm/kgH 2 O)

Method*

806 ± S.D. 117 506 ± S.D. 68.0 910 ± S.D. 98.3

VP VP FP

792 ± S.D. 100

FP

* See text for explanation of method.

ing in cocoons. The urea is eliminated when these lungfishes become free. The use of this one biochemical solution to these two problems suggests preadaption, presumably for aestivation. This also enabled the sarcopterygians to live out of water, and, ultimately, with the development of the loop of Henle and the ability to concentrate the urine far above the osmotic concentration of plasma, enabled mammals to live permanently on land. Hagfishes (Myxini) are also isosmotic but their serum ismolality is due primarily to inorganic salts (Robertson, 1963, and papers cited therein). Robertson (1963: 513) suggests that the hagfishes could be retaining a primitive system exhibited by such protovertebrates as the Cephalochordates, in which case it might be argued that hagfishes represent one "fish" lineage that never lived in fresh water, a view strongly opposed by Smith (1936) on the basis of the large glomeruli possessed by hagfishes, structures which are indicative of a freshwater ancestry. Osmolality. The circulating intravascular fluid volume in a leptocephalus is measured in microliters and several technical problems needed solution before acceptable data could be obtained on osmotic concentration in leptocephalus blood. Short plankton tows of 10 to 15 minutes at a depth of 50 meters consistently produced the greatest number of live leptocephali. All leptocephali were actively swimming immediately prior to cardiac puncture and withdrawal of fluid for osmometry. Osmolality by a vapor pressure osmometer (Model 5100 B, Wescor Inc., Logan,

Utah) was performed aboard ship. Samples for measurement of osmotic pressure by freezingpoint depression (Ramsay and Brown, 1955) were measured ashore with a Clifton nanoliter osmometer (Clifton Technical Physics, Hartford, New York). Cardiac puncture in leptocephali yielded sufficient sample for one non-repeatable reading in the vapor pressure (V.P.) osmometer, but gave more than enough for triplicate determinations of osmolality by freezing-point (F.P.) depression. When tested with sea water and large serum samples, the error in serial determinations was less than ±4 percent by the V.P. method and less than ± 1 percent by the F.P. method. As we show later, differences between measurements of osmotic pressure by both depression of vapor pressure and freezing point were not significant and reflect the nonvolatile, high electrolyte composition of our samples. We collected leptocephali and other marine organisms during cruises of the R/V Gilliss (1976, 1977), R/V Columbus Iselin (1977), and R/V Erin Leddy-Jones (1978-1982) in the Caribbean Sea, Straits of Florida, and Gulf of Mexico. The mean osmolality of sea water taken from a depth of 50 meters at 11 stations was 1058 mOsm/kg H2O with a range of 1042-1071. In Table 77, the mean values for standard length (t = 6.7) and osmolality (t = 9.6) between the two groups of premetamorphic and metamorphosing leptocephali of Ariosoma balearicum were significantly different, p < 0.001. The second two groups of premetamorphic larvae in Table 77 were from two different cruises and,

Fishes of the Western North Atlantic, Part 9

674

fl

y*997-3.66x

E

50

75 100 125 STANDARD LENGTH (mm)

FIGURE 711. Correlation of osmolality with standard length in premetamorphic leptocephali of the congrid Rhynchoconger flavus (double circles indicate 2 coincident data points).

although the size ranges were similar, the mean values for osmolality differed significantly. In this instance, the data were not combined and were left standing as two different populations. Most noteworthy is that the average serum osmotic concentration of the premetamorphic larvae was equal to % the value of the ambient sea water. Studies of smaller premetamorphic larvae of this species may show that the early larvae are isosmotic. In the course of three consecutive plankton stations during a late winter cruise (Feb.-Marv 1977), we collected 7 live premetamorphic leptocephali of the congrid Rhynchoconger flavus. Values for osmolality ranged from 620 to 1030 mOsm/kg H2O and standard length from 50 to 87 mm. Several months later during a summer cruise (July-Aug., 1977), we collected 18 premetamorphic leptocephali of the same species in 7 plankton tows. The leptocephali of the second group were larger, 50 to 117 mm TL, and the osmolality lower, 535 to 865 mOsm/kg H2O. We recognize that, in all likelihood, our leptocephali came from two different spawning populations, but, in an effort to obtain a correlation between growth and blood toxicity, we have combined the data of the two samplings (Fig. 711). In the short segment of the life cycle of R. flavus shown in Figure 711, prior to onset of metamorphosis, the blood osmotic concentration decreases pro-

gressively with length. Calculated from the regression line, a larva of 50 mm TL would have an osmolality of 804 mOsm/kg H2O. In a 100 mm larva the osmolality drops to 611. In this instance, graphic presentation is more informative than calculation of mean standard length (73.5 ± S.D. 19.0 mm) and mean osmolality (713 ± S.D. 137 mOsm/kg H2O) for the 25 leptocephali. An abundance of muraenid leptocephali were collected in late summer, 1977. Forty-nine live, premetamorphic leptocephali of Gymnothorax nigromarginatus came from 22 plankton stations. The sampling was too scattered to show a linear relationship between osmolality and length, but 13 larvae had a blood osmotic concentration in excess of one osmol. Mean osmolality was 852 ± S.D. 153 mOsm/kg H2O; standard length, 54.3 ± S.D. 12.1 mm. The remainder of the data on osmotic pressure in premetamorphic anguillif orm leptocephali is given in Table 78. In the tow immediately following the collection of a small premetamorphic larva of Nessorhamphus ingolfianus (Table 78, TL 40 mm, 938 mOsm/kg H2O), we caught a metamorphosing larva of the same species. It measured 112 mm TL and had a blood osmotic concentration of 622 mOsm/kg H2O. Although we did not find live premetamorphic larvae of the muraenid Anarchias similis, we did collect blood from three metamorphosing larvae. Standard lengths were 44, 57, and 51 mm, and blood osmolalities, each from a single sample, were 554, 537, and 650 mOsm/kg H2O, respectively. Because a vapor pressure osmometer that requires only 5 jil of sample is a relatively new instrument for shipboard use, we measured the blood osmotic concentration of a number of marine fishes and cephalopods for side by side comparison with our leptocephalus data. All osmolality measurements in Table 79 were made with the Wescor vapor pressure osmometer. The first success with artificial maturation of silver eels to produce mature eggs and sperm by hormone injection was reported by Yamamoto and Yamauchi (1974). Fertilized eggs hatched in 38-45 hours and the leptocephali survived until

675

Leptocephali: Evolutionary Significance

TABLE 78. Blood osmolality of premetamorphic anguilliform leptocephali.

Family and species Congridae Uroconger syringinus Paraconger caudilimbatus Gnathophis sp.

Standard length (mm) (range)

Osmolality (mOsm/kg H2O) (range)

71 78 86 (57-105) 73

941 967 787 (535-1057) 652

Muraenidae Gymnothorax moringa Ophichthidae Ophichthus gomesi Myrophis punctatus Ahlia egmontis

Number

652

57

88 (69-118) 48 93 (86-97) 105 87 80

782 (570-982) 910 730 (543-1008) 583

1 5

845 1020

1 1 1

126

763

1

Chlopsidae Chilorhinus suensoni

52

518

1

Derichthyidae Nessorhamphus ingolfianus

40

938

1

Ophichthus spinicauda Bascanichthys scuticaris Bascanichthyini sp. Muraenesocidae Xenomystax sp.

Nettastomatidae Hoplunnis macrura

107 (68-122)

the fifth to sixth day when the yolk sac was effectively exhausted. From a similar experiment conducted by David G. Smith, we obtained blood samples for osmolality (V.P.) from hormone treated male and female silver eels of Anguilla rostrata. There were 19 male and 11 female eels all acclimated to sea water in laboratory tanks with osmolalities ranging from 1010 to 1216 mOsm/kg H2O. Females (mean weight 428 g) were several times larger than males (mean weight 64 g). Mean serum osmolality in 19 male eels was 345 ± S.D. 37.0 mOsm/kg H2O, and in 11 females, 310 ± S.D. 12.1 mOsm/kg H2O. The difference between mean values is significant (t = 4.20, p = < 0.001).

579 (483-657)

5

In concluding this study on the colligative properties of blood, we made a comparative study of our methodology for measuring osmolality. Osmotic concentration by both vapor pressure and freezing-point depression was measured in triplicate on 11 samples of Anguilla rostrata sera, 4 samples of blood from the bay squid Lolliguncula brevis, and in the sea water of their respective holding tanks. The data are summarized in Table 80. By x2 test/ ^e differences in mean osmolality between the two methods were not significant. Discussion. The leptocephalus solves the osmotic problems of the larva by being nearly isotonic with sea water. Hulet et al. (1972) studied the electrolyte composition of leptocephali and

676

Fishes of the Western North Atlantic, Part 9

TABLE 79. Blood osmolality of adult marine fishes and cephalopods collected during trawling and night-lighting stations in the Caribbean Sea and Gulf of Mexico (1976,1977). Species

Blood osmolality (mOsm/kg H2O)

Gymnothorax nigromarginatus Coryphaena hippurus Gonostoma denudatum Myctophum punctatum Synodus synodus Trachinocephalus my ops

Upeneus parvus Priacanthus arenatus

Melanostomiidae Raja texana Loligo pealei

Ommastrephes pteropus

534 466 502 528 492 478 486 521 482 492 476 486 (463-512) 495 (439-534) 384 1062 1034 1040 1052 1037 1067 1072

Comment* 260 mm TL, s 600 mm TL, p, i, t 1320 mm TL, p, I, t s 125 mm TL, s s 300 mm TL, s, d 360 mm TL, s, d 222 mm TL, s, d 215 mm TL, s 220 mm TL, s, d 125-140 mm TL, p, n = 5

125-226 mm TL P/ n = 7 tP s s d t

s = serum, p = plasma, m = male, f = female, d = average of 2 measurements, t = average of 3 measurements.

concluded that these larvae are physiologically unique and more in ionic equilibrium with sea water than any other fishes with the exception of the hagfishes. This conclusion has been overlooked in recent literature (e.g., Nelson 1984: 31; Lutz 1975). Pfeiler (1984a) demonstrated decreasing concentrations of sodium chloride during metamorphosis of leptocephali of the bonefish (Albula). Inorganic salts are involved and sodium chloride is the major inorganic electrolyte found in the leptocephalus. Thus, it would seem that the leptocephalus offers a third pathway for invasion of the sea, one that permits completion of a marine life cycle by permitting a prolonged period for maturation of the osmoregulatory process. Tables 77 and 78, and Figure 711 show the changes of osmolality which occur in several species of eels from the premetamorphic to the late metamorphic stage.

Many primitive bony fishes (e.g., sturgeons, salmonids) spend much of their adult life in the sea returning to fresh water to spawn, a life history style termed anadromy. Although the adults of such fishes can osmoregulate, they are unable to complete their life history in the sea. We suggest that the leptocephalus evolved as a means of achieving permanent residency in the sea by delaying or avoiding the osmotic problem until metamorphosis at which time the kidneys and salt-secreting organs take over, and that this was as important an evolutionary step in freeing early actinopterygian fishes from the fresh water as was the development of the impermeable egg shell and membranes which freed land vertebrates from fresh water. How, or under what environmental circumstances it was triggered, we do not know. If we are correct in this assumption, then two other arguments follow: (1)

Leptocephali: Evolutionary Significance

TABLE 80. Comparison of vapor pressure and freezing point methods in an eel (Anguilla) and a squid (Lolliguncula) for measurement of osmolality. Milliosmols per kg of water

Anguilla rostrata (n=ll) Blood serum Holding tank Lolliguncula brevis (n=4) Whole blood Holding tank

Vapor pressure (Wescor)

Freezing point (Clifton)

317 ± S.D. 15.6 1093

334 ± S.D. 26.7 1112

872 ± S.D. 12.9 840 ± S.D. 21.8 832 838

that fishes later succeeded in pushing the solution of the osmotic problem into the larval stage and thus eliminated the leptocephalus stage; (2) that possession of a leptocephalus larva is a primitive or plesiomorphic character which cannot be used to prove relationships beteen groups which have it. The second implies nothing less than a complete reexamination of the structure and composition of the Elopomorpha. Our base of knowledge of the fine structure of the leptocephalus rests largely on the work by Hulet (1978). This was based on study of the leptocephalus of certain eels from the Straits of

677

Florida, Caribbean Sea, and Gulf of Mexico, principally the congrid Ariosoma balearicum (Delaroche). The small size and short life of the leptocephalus of the tarpon, Megalops atlanticus Valenciennes compared to that of the ladyfishes, Elops, may indicate that Megalops represents one group or step on the way to the loss of the leptocephalus and that, as suggested on other grounds by Greenwood (1977), it and Elops are, at best, distantly related. As noted elsewhere (Robins, this volume), the leptocephalus of the family Monognathidae is quite different from that of other gulper eels (Saccopharyngiformes). The very threadlike and large leptocephali of the Notacanthiformes may indicate much more distant relationships to the Albuliformes or Elopiformes than is currently believed. In short, in using the leptocephalus as a systematic glue to build the Elopomorpha, we have constructed a seriously flawed system that is already cracking and which may crumble. Although specializations in various types of leptocephali (e.g., the diagonally elongate eye of the Synaphobranchoidea, see Robins and Robins, this volume) may provide valid specialized or apomorphic bases for characterizing genera, families, or superfamilies, the mere fact that a fish has a leptocephalus is, we believe, of limited systematic significance, denoting the retention of a primitive system.

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Orders Anguilliformes and Saccopharyngiformes Leptocephali DAVID G. SMITH Characters. Small to large leptocephali, showing great variation in all characters. Caudal fin small and round, continuous with dorsal and anal fins (some ophichthids have secondarily lost the caudal fin). Pectoral fin present although sometimes reduced. Pelvic fins always absent. Composition. Leptocephali of all but four eel families have been collected in the western North Atlantic. The monotypic Myrocongridae is known only from the eastern Atlantic and only from two specimens; its leptocephalus is unknown. Adults of the Colocongridae, Muraenesocidae, and Heterenchelyidae do occur in the area, but their leptocephali have not yet been recorded here. Muraenesocid leptocephali are known only from metamorphic specimens, and the illustrations available in the literature are not very good. Consequently, I have not included them in this account. Blache (1977: 63) provided good descriptions and illustrations of several west

African heterenchelyid species. The only colocongrid leptocephalus known is an advanced metamorphic specimen described by Castle (1969a: 7); most of the larval characters were already gone. The key below has certain limitations. It does not apply to very young individuals; distinguishing characters develop with growth, and leptocephali smaller than about 10 mm SL are difficult to identify. At the other end of the growth scale, important characters are often lost at metamorphosis. Damaged or faded specimens will be difficult to identify because of the importance of such characters as pigmentation and fin position. A few species may not show the characters typical of their families. For example, the congrid Acromycter greatly resembles an ophichthid, and some ophichthids have greatly reduced intestinal loops, which are normally characteristic of the family.

KEY TO THE ANGUILLIFORM LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC la. Eye telescopic 2 (Synaphobranchidae) lb. Eye normal 3 2a. Intestinal pigment absent; gut a simple, straight tube; rostral filament absent Synaphobranchinae, p. 682 2b. Intestinal pigment present; gut with several small, irregular swellings; rostral filament sometimes present Ilyophinae, p. 686 3a. Head deep with elongate hyomandibula; gut with a single pigmented swelling at posterior end Saccopharyngoidei, p. 948 3b. Head and jaw suspension normal 4 679

680 4a. 4b. 5a. 5b. 6a. 6b. 7a. 7b. 8a.

Fishes of the Western North Atlantic, Part 9

Liver with two or three discrete lobes, with gall bladder on posteriormost lobe 5 Liver undivided, form variable 6 Nephros terminates 0-15 myomeres before anus Ophichthidae, p. 764 Nephros terminates more than 15 myomeres before anus . . Congridae (part, Acromycter), p. 758 Gut with one or more swellings or loops, or with irregular undulations 7 Gut a simple, straight tube, with at most a very slight swelling in area of liver 13 Gut with a single, pigmented loop at posterior end 8 Gut with two or more swellings or loops, or with irregular undulations 9 Intestinal loop simple, with a single expanded melanophore; gastric region located posteriorly, Moringuidae, p. 699 near loop 8b. Intestinal loop complex, covered with numerous small melanophores; gastric region located T anteriorly, before midlength of gut 7Pe I (unidentified), p. 973 9a. Gut with two swellings, one associated with liver and one near anus Nettastomatidae (part), p. 704 9b. Gut with three or more swellings or loops, or with irregular undulations 10 lOa. Body deep, intestine with 3-4 well formed loops; myomeres fewer than 120 Cyematidae, p. 944 lOb. Body shallow, intestine either with several low loops or with irregular undulations; myomeres 11 more than 120 lla. Intestine with several low loops posteriorly; preanal length about % SL; pigment scattered over side of body Congridae (part, Pseudophichthys), p. 757 lib. Intestine with irregular undulations rather than discrete loops or swellings; preanal length less than half SL; pigment confined to midline or ventral half of body 12 12a. Fleshy keel overhanging nape Type II (unidentified), p. 977 Nettastomatidae (part, Facciolella), p. 720 12b. No fleshy keel on nape 13a. Melanophores absent Anguillidae, p. 898 13b. At least some melanophores present 14 14a. Intestinal pigment absent 15 14b. Intestinal pigment present 17 15a. Pectoral fin greatly reduced; gut less than half SL; dorsal and anal fins restricted to tip of tail Muraenidae (part, Anarchias), p. 901 15b. Pectoral fin well developed; gut more than half SL; dorsal and anal fins not restricted to tip of tail 16 16a. LVBV near myomere 59-80 Derichthyidae, p. 917 16b. LVBV near myomere 30-37 Serrivomeridae, p. 921 17a. Pectoral fin greatly reduced; posterior nostril, when developed, above mideye level; tail usually broadly rounded Muraenidae (part), p. 900 17b. Pectoral fin well developed; posterior nostril near or below mideye level 18 18a. Small but distinct deep-lying pigment spots along top of notochord; body elongate; nasal capsule very small; intestinal melanophores small, restricted to top of gut Nemichthyidae, p. 925 18b. No pigment spots on top of notochord; body variable; nasal capsule moderately large; intestinal melanophores large or small, at least some on bottom of gut as well as top 19 19a. Preanal length half SL or less Chlopsidae, p. 933 19b. Preanal length more than half SL 20 20a. Head short and deep, dorsal profile broadly rounded; no crescentic patch of pigment below eye Heterenchelyidae, p. 943

Anguilliform Leptocephali

681

20b. Head usually moderate, not broadly rounded in dorsal profile; crescentic patch of pigment sometimes present below eye 21 21a. Jaws broad and shovel-shaped; lower teeth bicuspid . . . . Ascomana eximia (unidentified), p. 979 21 b. Jaws not broad and shovel-shaped; lower teeth unicuspid Congridae, p. 723 also Leptocephalus thorianus (unidentified), p. 978

Family Synaphobranchidae: Leptocephali D A V I D G. SMITH

Characters. Leptocephali of the Synaphobranchidae are uniquely characterized by the so-called telescopic eye. The eye is somewhat elongate in an anterodorsal-posteroventral direction, with the lens at the anterodorsal end. The main visual axis is thus directed upward, forward, and outward. As in other marine animals with telescopic eyes, this character seems related to the depth of habitat. Synaphobranchid leptocephali are collected at significantly greater depths than are most other leptocephali. Composition. Synaphobranchid leptocephali come in two rather different types, and these will be characterized separately. Leptocephali of Synaphobranchus have a simple gut without pigment of any kind. Lateral pigment, when present, consists only of a large, diffuse spot centered on the notochord slightly before the anus. The central section of the myomeres around the notochord is somewhat more opaque than the remainder and gives the appearance of a broad, white stripe running along the longitudinal axis of the body.

In the other group of Synaphobranchid leptocephali, the gut is heavily pigmented and has a series of irregular swellings or loops. This group is considerably larger and more diverse than the Synaphobranchus group. Lateral pigment may be present or absent, and a rostral filament is sometimes present. One of the leptocephali in this group has been conclusively identified with Dysomma brevirostre and another, somewhat more tentatively, with Dysomma anguillare. Another may represent the genus Dysommina, but the majority cannot yet be identified with an adult. Whether these two larval types reflect in every case the division between the Synaphobranchinae and the Ilyophinae is uncertain. Most of the leptocephali in the Dysomma group remain unidentified. In particular, the leptocephali of such nearly intermediate genera as Haptenchelys, Ilyophis, and Meadia are unknown. For convenience, the leptocephali will be treated here as representing the subfamilies Synaphobranchinae and Ilyophinae, but it should be born in mind that such identifications are still tentative.

Subfamily SYNAPHOBRANCHINAE Characters. Moderate-sized leptocephali, maximum SL about 120-170 mm. Body moderately elongate, tail not sharply pointed, preanal length about 70-80% SL. Dorsal fin begins a short distance before anus; caudal fin with 16-18 rays. Pectoral fin well developed. Gut a simple, straight tube without loops or swellings. Head rather short, nasal capsule at about midsnout. Eye telescopic, directed obliquely outward, upward, and forward. Pigment largely confined to small melanophores on base of tail and caudal fin. Some Indo-Pacific forms have a

large spot on lateral midline just before anus. Central section of myomeres around notochord more opaque than dorsal and ventral parts, giving effect of a broad, white stripe. Composition. With the exception of certain IndoPacific forms that have a black spot around the notochord, leptocephali of synaphobranchine species can be separated only by meristic characters. This complicates identification because several species have overlapping vertebral counts. A further complication is that we do not know how widely representative the synaphobran682

Synaphobranchid Leptocephali chine larval type is. Do Diastobranchus and Haptenchelys have the same type of leptocephalus, or is this type limited to Synaphobranchus itself? Bruun (1937) studied the synaphobranchine leptocephali of the Dana collections and found that the Atlantic specimens fell into two groups, one with 131-140 myomeres and one with 143154 myomeres. He assigned the latter group to Synaphobranchus kaupi (146-152 vertebrae in Atlantic specimens). This identification is probably correct. Synaphobranchus kaupi is common and widespread and has the highest vertebral count of all the North Atlantic species. Synaphobranchus oregoni has 142-148 vertebrae, however, and this species was unknown to Bruun. The only other synaphobranchine he knew of was Synaphobranchus bathybius (126-137 vertebrae in the Atlantic), and he assigned his second group of leptocephali to this species. Synaphobranchus affinis and S. brevidorsalis, however, have similar vertebral counts (128-139 and 131-134, respectively). The specimens examined for this study fell into the same two groups: 131-135 and 149-153 myomeres. At the present state of knowledge, neither group can be identified with certainty, although the high-count form probably represents Synaphobranchus kaupi, at least in part. ?Synaphobranchus kaupi Johnson, 1862 Figure 712 Leptocephalus Synaphobranchi pinnati. Collett, 1905: 387, fig. 147. Schmidt 1906: pi. 9, figs. 4-6; 1909a: 7. Lea, 1913: 14, figs. 5-9, pi. 2, nos. 1-4. L. Synaphobranchus kaupi. Bruun, 1937: 10. Synaphobranchus kaupi. Keller, 1976: 68.

Description (including data from Bruun, 1937, and Keller, 1976). Total myomeres 143-154 (n = 275), preanal myomeres 98-107 (270), predorsal myomeres ca 12-19 fewer than preanal, LVBV 68-73 (41), caudal-fin rays 16-18 (18). Proportions as % of SL: preanal 75-81 (131), head 8-11 (4), greatest depth 9-11 (4). Size. Maximum size about 130 mm SL. Identification. Although it cannot be guaranteed that all of the leptocephali described here belong to Synaphobranchus kaupi, most of them

683

probably do. The vertebral count of S. kaupi (144152) fits the present leptocephali slightly better than does that of S. oregoni (140-150). In addition, S. kaupi has a more northerly distribution; it occurs north of the northern Straits of Florida on the continental slope and is found in the eastern Atlantic as well. Synaphobranchus oregoni, by contrast, seems limited to the Gulf of Mexico and Caribbean. The leptocephali are found across the North Atlantic mainly north of 30°N. Ilyophis brunneus has 145-151 vertebrae, but that species has now been assigned to the Ilyophinae. It is therefore unlikely to have a leptocephalus of the synaphobranchine type, but the possibility cannot entirely be ruled out. Spawning and Growth. Brunn (1937: 15) found a pronounced seasonal pattern to the size distribution of the leptocephali. The smallest specimens, about 20 mm SL, were collected between January and March, and the average size increased as the year went on. In May the size range was 34-50 mm, and in October 47-73 mm. During the spring and summer, two distinct size groups were found. The larger one, approximately 80-130 mm, represented the previous year class. The leptocephali thus seem to take about a year and a half to reach full size and metamorphose. The few specimens available for study here show a similar pattern. The smallest specimen, 25 mm SL, was taken in March. Four specimens collected in June measured 45-58 mm and four in September 55-88. Remarks. Bruun's data on the distribution of Synaphobranchus kaupi leptocephali raise some puzzling questions. He found a general increase in size from west to east, as in the case of Anguilla anguilla. Leptocephali smaller than 30 mm SL were found only west of about 65°W; leptocephali larger than 80 mm occurred only east of 30°W and north of 40°N. The picture is one of leptocephali being spawned in the western Atlantic and drifting eastward across the ocean as they grow, again similar to the case of Anguilla anguilla. Adults of Synaphobranchus kaupi, however, occur commonly off the North American coast. How do they get there if all the metamorphic leptocephali are on the other side of the Atlantic?

Fishes of the Western North Atlantic, Part 9

684

10 mm

B

FIGURE 712. Synaphobranchus kaupi: MCZ 70321. A. Whole view. B. Head. C. Tail.

Bruun suggested that the eels "wander about a good deal" after taking up life on the bottom. This would require a great deal of wandering indeed. Synaphobranchus kaupi has been collected down to about 3500 m (Bruun, 1973: 8; Grey, 1956:146), but this is still substantially less than the depth of the abyssal plain that the eels would have to cross. For the present, we can only note this as another unsolved eel problem. Distribution. Across the North Atlantic from the Bahamas to North Africa and the British Isles, but not the Mediterranean. Except for the extreme western and eastern ends of the range, these leptocephali are found exclusively north of 30°N. Bruun (1937: 17) found that most of the leptocephali were collected in nets fished with about 400-700 m of wire out. Assuming an approximate wire-to-depth ratio of 3:1, the depth of occurrence is about 130-230 m. This is substantially greater than that of most other leptocephali, which are most frequently captured in the upper 100m. Study Material. Nine specimens, 25-88 mm SL. SARGASSO SEA: UMML Sands 13-B (1, 25), 25°15'N, 72°45'W/ 0-96 m, 25 Mar. 1966. GULF STREAM: MCZ 62298 (1, 52), 36°58.4/N, 73°36.8'W/ 19 June 1982. 62299 (1,45), 37°00.3'N, 73°04.1'W/ 0-251 m, 21 June 1982.62301 (1, 58), 37°05.4'N, 73°46.9'W/ 0-1000 m/ 26 June 1982. 70321 (1, 54), 37°00.3'N, 73°04.1'W/ 251-374 m, 21 June 1982. EASTERN ATLANTIC: UMML 402-6-T1-B (1, 88),

45°06'N/ 25°00'W/ 850-1200 mwo, 1 Sept. 1967. 402-6T2-D (2,55-56), 45°07'N/ 24°42'W, 500 mwo, 2 Sept. 1967. 402-6-T3-C (1, 87), 45°08'N/ 24°53'W/ 1200 mwo, 2 Sept. 1967.

Synaphobranchus species Leptocephalus Histiobranchi infernalis (or L. Ilyophidis Brunnei). Lea, 1913: 17, fig. 10, pi. 2, no. 5. L. Synaphobranchus infernalis. Bruun, 1937: 11. Histiobranchus bathybius. Keller, 1976: 71.

Description (including data from Bruun, 1937 and Keller, 1976). Total vertebrae 131-140 (n = 50), preanal myomeres 83-101 (44), predorsal myomeres 74-80 (3), LVBV 68 (1), caudal-fin rays 16-17 (6). Proportions as % of SL: preanal 69-81 (6), head 9-13 (2), greatest depth 10 (1). Size. Maximum size about 90 mm SL. Bruun (1937: 20) reported two glass eels of 78 and 79 mm. Identification. Bruun assigned these leptocephali to Synaphobranchus bathybius (= S. infernalis) because it was the only other synaphobranchine species he knew of in the Atlantic. The vertebral count of S. bathybius (126-140) matches the myomere count of the present leptocephali, but so do the count of S. affinis (125-140) and S. brevidorsalis (130-140), of whose presence in the Atlantic he was unaware. One piece of evidence given by Bruun himself suggests that he was dealing with a species other than bathybius. In

Synaphobranchid Leptocephali Synaphobranchus bathybius the dorsal fin begins over the pectoral fin, whereas in the other species it begins behind the anus. Bruun (1937:11) stated that in the glass eels the anus had advanced to a point in front of the dorsal-fin origin. He explained this by assuming that the dorsal fin moves forward at a later stage, but by the time metamorphosis has progressed to the glass-eel stage, movement of the dorsal fin should be well under way. It is more likely that the dorsal fin in Bruun's specimens had already reached the definitive position and that its origin would remain behind the anus. Lea (1913: 18) gave Ilyophis brunneus as an alternative identification for his leptocephalus, because he found 132 vertebrae in the specimen of that species he examined. Other sources, however, indicate that I. brunneus has 145-151 vertebrae and hence cannot belong to the present leptocephalus. A conclusive identification of these leptocephali cannot yet be made. Synaphobranchus affinis is common on the Atlantic continental slope of the United States and is probably represented by at least some of the leptocephali, but S. brevidorsalis and S. bathybius cannot be ruled out. Spawning and Growth. Bruun found that the smallest leptocephali, less than 30 mm SL, were collected from December to March, which indicates a fall or winter spawning season. They grow much faster than the leptocephali of Synaphobranchus kaupi, reaching their full size of 8090 mm by summer. The shorter larval life perhaps explains why they are not found in the eastern Atlantic; the journey is simply too long for them. Bruun's two metamorphic specimens were taken 3 months apart in May and August. The small specimens of less than 30 mm were also taken over a 3-month period. There is no way to tell directly how old a 30-mm leptocephalus is, but judging by the diagram plotting size against date of capture (Bruun, 1937: 20, text-fig. 10), 2 months would be a reasonable estimate.

685

The same diagram shows an interval of 5 months between the first capture of a sub-30-mm leptocephalus (December) and the first capture of a metamorphic specimen (May). There is also a 5-month interval between the last small leptocephalus (March) and the last metamorphic specimen (August); a metamorphic specimen collected in September (MCZ 62297) does not change the pattern greatly. Adding 2 months to this gives a total duration of larval life of about 7 or 8 months. The scenario that arises out of this analysis is a spawning season that begins in September and runs through December, followed by a 7- to 8-month growth period. Metamorphosis would take place from April to September. Other evidence seems to support this. Wenner (1975) described 89 elvers of Synaphobranchus affinis collected off North Carolina on 29 April 1973. At 72-105 mm TL, they were probably not long past metamorphosis. Keller's (1976:70) specimens follow the pattern, too, with a metamorphic individual in June. The consistency of these figures suggests that most of the leptocephali belong to a single species. If this is correct, the species is most likely to be Synaphobranchus affinis. Distribution. Unlike the leptocephali of Synaphobranchus kaupi, the present leptocephali are largely restricted to the western Atlantic. Bruun (1937:21) found only two specimens east of 40°W and they were nearly full size. Leptocephali smaller than 30 mm were found only around the Bahamas and the Greater Antilles. Most of the specimens reported by Bruun (1937: 20) were taken with 400-700 m of wire out. Study Material Five specimens, 26-75 mm SL. SARGASSO SEA: UMML Pillsbury 1373 (1, 75), 23°14.5'N/ 64°42'W, 0-2250 m, 1 July 1971. GULF STREAM: MCZ 62297 (1, 64 metamorphic), 40°14'N, 63°28'W, 500-750 m, 24 Sept. 1981.62300 (1,75), 37°05.4'N, 73°46.9'W, 0-1024 m, 25 June 1982.62302 (1,68), 37°00.9'N, 71°17.5'W/ 0-1004 m, 20 Aug. 1982. STRAITS OF FLORIDA: UMML SL 14 C-2 (1, 26), 25°35'N, 79°25'W, 19-20 Mar. 1953.

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Fishes of the Western North Atlantic, Part 9

Subfamily ILYOPHINAE Characters. Moderately small to large leptocephali, maximum size usually less than 100 mm SL, but up to 200 mm in at least one species. Body moderately elongate, tail not sharply pointed, preanal length about half to two-thirds SL. Length of dorsal fin between a third and twothirds SL; caudal fin well developed, its rays slightly separated from those of adjacent dorsal and anal fins. Pectoral fin well developed. Gut with several irregular thickenings along its length. Kidney tubular, extending along top of gut almost to anus. Head short to elongate, snout sometimes bearing a rostral filament of various length and thickness. Eye telescopic, directed obliquely outward, upward, and forward. Nasal capsule closer to tip of snout (excluding filament) than to eye. One or two teeth on each side at tip of snout on rostral cartilage (one tooth in forms with a rostral filament, two in those without), followed by 7-12 lateral teeth on upper jaw, the anterior ones sometimes larger than posterior. One tooth at tip of lower jaw, followed by 7-18 lateral teeth, the anterior ones sometimes larger than the posterior. Lower teeth often larger than upper. A variable number of dendritic melanophores externally on intestine and sometimes on ventral body wall behind anus. Melanophores sometimes present on midlateral body wall, superficial or deep. Some species have additional melanophores between midlateral line and ventral margins of myomeres around midbody. Pigment on throat, around brain, jaws, and rostral filament.

Composition. A rich variety of ilyophine leptocephali exists, but only one or two can be identified confidently with a specific adult. The arrangement of the group presented here is based on an unpublished study by D. G. Smith and P. H. J. Castle on the ilyophine leptocephali of the Dana collections. The leptocephali are divided into four major groups based on the presence and form of the rostral filament and the presence or absence of lateral pigment. The group designated by the letter A lacks both a rostral filament and midlateral pigment. Group B lacks a rostral filament but has midlateral pigment. Group C has a stout rostral filament, long or short, with a pair of teeth at the tip; the head can be long or short, and there is no midlateral pigment. Group D has a slender filament without teeth; the head is short, and midlateral pigment is present. Within each group, individual species or species groups are recognized by variation in the head length, the form of the filament, pigmentation, and number of myomeres. Where adult or larval names are not available, species are designated by numbers (Alx C5, etc.). The designation system follows that of Smith and Castle (unpubl.), but only those forms known from the North Atlantic are treated here. Remarks. In measuring those forms with a rostral filament, the filament itself is not included. SL, HL, preanal, and predorsal lengths are measured from the base of the filament. Distribution. Ilyophine leptocephali are known from the Atlantic and Indo-West Pacific, but have not been recorded from the eastern Pacific.

KEY TO THE ILYOPHINE LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC la. Ib. 2a. 2b. 3a. 3b. 4a. 4b. 5a.

Rostral filament absent Rostral filament present Midlateral pigment absent Midlateral pigment present Total myomeres 118-128 Total myomeres 170-205 Total myomeres 170-174 Total myomeres 193-205 Total myomeres 141-149

2 7 3 (Group A) 5 (Group B) ?Dysomma anguillare, p. 687 4 Species Ag/ p 689

Dysomma brevirostre, p. 689 Species 3^ p 690

Synaphobranchid Leptocephali

687

5b. 6a. 6b. 7a.

Total myomeres 173-177 6 Preanal myomeres ca 62 Species B7, p. 691 Preanal myomeres 75-78 Species Bn, p. 691 Rostral filament stout, rod-like, often bearing a pair of teeth at tip; no midlateral pigment . . 8 (Group C) 7b. Rostral filament slender, thread-like, without teeth; conspicuous lateral pigment present . . . 10 (Group D) 8a. Rostral filament longer than head (Fig. 716) Leptocephalus rostratus, p. 693 8b. Rostral filament shorter than head (Fig. 715) 9 9a. Preanal myomeres 68-72 Species Q, p. 691 Species C2, p. 692 9b. Preanal myomeres ca 89 lOa. Melanophores present on ventral margin of myomeres slightly before anus and/or on side of 11 body above and below midlateral series lOb. Lateral pigment confined to midline 13 1 la. Melanophores on lateral midline, but no additional melanophores above and below them (Fig. 717) Leptocephalus proboscideus, p. 693 lib. Extra melanophores immediately above and below midlateral series (Fig. 718) 12 12a. Total myomeres 128-133 Species D4, p. 696 12b. Total myomeres 124 Species D5, p. 696 13a. Total myomores 117-119 Species D7, p. 697 13b. Total myomeres 128-138 14 14a. Midlateral melanophores superficial Leptocephalus dolichorhynchus, p. 697 14b. Midlateral melanophores mostly subcutaneous 15 15a. Preanal myomeres 77-79; total myomeres 135-138 Species D3, p. 695 15b. Preanal myomeres 71; total myomeres ca 127 Species Dlx, p. 697 GROUP A Characters. Head and snout long; rostral filament absent; no midlateral pigment. Composition. At least ten species exist, six in the Indo-Pacific and four in the Atlantic. Types Ai-A3 and A6-A8 are Indo-Pacific. Type A4 is identified as Dysomma anguillare, and Type A10 is Dysomma brevirostre. The three western Atlantic forms are distinguished mainly by the number of myomeres. ?Dysomma anguillare Barnard, 1923 Figure 713 Dysommidae Type I. Smith, 1974:673, fig. 1. Keller, 1976: 43. Dysomminae. Smith, 1979: fig. 5.

Distinctive Characters. This leptocephalus has fewer myomeres than the other western Atlantic members of the group (118-128 vs 170-205).

Description. Total myomeres 118-128 (n = 35), preanal myomeres 57-62 (35), predorsal myomeres 45-48 (8), LVBV 60-64 (11), caudal-fin rays 11-12 (10). Proportions as % of SL: preanal 5073 (117), predorsal 44-49 (6), HL 10-15 (36), greatest depth 11-19 (22). Pigmentation. Dendritic melanophores on gut, two dendritic melanophores in line with these behind anus on body wall below myomeres. Melanophores below heart, at angle of jaw, lateral to brain. Small melanophores on base of anal fin. Size. The largest specimen examined was 64 mm SL (UMML Pillsbury 825). Identification. Of the six ilyophine species known from the western Atlantic, only Dysomma anguillare has a vertebral count that matches the myomere count of the present leptocephalus (119-130). The leptocephalus is relatively common and therefore is likely to belong to a known species. Dysomma anguillare is also fairly common and widely distributed in the western North At-

688

FIGURE 713.

Fishes of the Western North Atlantic, Part 9

Dysomma anguillare: MBI 47, 55 mm SL, Gulf of Mexico. A. Whole view. B. Head. C. Tail.

lantic. Without metamorphic specimens a conclusive identification is impossible, but the evidence strongly suggests that this leptocephalus is Dysomma anguillare. Spawning and Growth. Although this is by far the most common ilyophine leptocephalus in the western North Atlantic, its occurrence is too spotty to reveal clear seasonal trends. Of 174 specimens collected during the MBI cruises, 115 came from just two stations. In the Gulf of Mexico, the species was collected in all seasons. Specimens smaller than 20 mm SL were collected in November and April, and in November alone specimens ranged from 6-55 mm SL. A prolonged spawning season seems indicated. Distribution. Gulf of Mexico, Straits of Florida, Caribbean, West Indies, and off South America at least to Brazil. There are four specimens from the Gulf Stream off North Carolina and one from the Central Atlantic about 2000 km east of Bermuda. Like all synaphobranchids, this leptocephalus lives at greater depths than most eel larvae. Dur-

ing the MBI cruises, for example, fully half the stations at which it was collected (11 of 22) were made with more than 150 m of wire out (mwo), and five of these with 500 mwo or more. As only 17% of the total number of stations were made with more than 150 mwo, these leptocephali must occur in the lower part of the sampled depth range. The Dana collections show a similar pattern: only two of 46 stations were made with less than 300 m of wire. Study Material. 334 specimens, 6-64 mm SL. GULF STREAM: ZMUC Dana 1342 VII (1, 45), 1345 II (3, 38-42). STRAITS OF FLORIDA: ZMUC Dana 1231 II (2,23-24). UMML Gerda 350 (1, 37). UMML SL 126-4 (1, 26). GULF OF MEXICO: UMML Gerda 207 (1,49). ANSP 154175 and 156183 (61,27-45), 156167 (3, 21-28), 156168 (5, 40-47), 156169 (4, 47-48), 156170 (2, 31-33), 156171 (6, 39-49), 156173 (1, 29), 156174 (4, 6-9), 156175 (1, 39), 156176 (1, 31), 156177 (1, 15), 156178 (1, 52), 156179 (3, 6-10), 156180 (1, 27), 156181 (11, 42-52), 156182 (8, 3454), 156184 (2, 29-50). MBI 47 (1, 55), 62 (1, 47), 63 (2, 68), 324 (1, 47). BAHAMAS: ZMUC Dana 1238 II (1, 24). UMML ONR TOTO 3-3 (1, 43), 6-4 (1, 52), 13-3 (1, 52). CUBA: ZMUC Dana 1225 II (4, 21-29), 1225 III (1, 23),

Synaphobranchid Leptocephali 1228 II (4, 30-34), 1229 II (11, 24-36), 1230 III (1, 24), 1230 IV (19, 22-49). PUERTO RICO: UMML Pillsbury 825 (1, 64). VIRGIN ISLANDS: ZMUC Dana 1192 V (1, 54), 1196II (2, 31), 1198 III (6,25-35), 1266 III (7, 33-38), 1269 VIII (1, 20), 1270 III (6, 37-46), 1270 IV (7, 36-42), 1270 V (3, 27-39), 1273 II (1, 41), 1273 VIII (1, 40), 1280 III (1, 50), 1281 IX (1, 33), 1291 III (2, 34-46), 1292 III (1, 44), 1293II (1,48), 1294II (2,45-47), 1294 III (1,40), 1296 111(2,32-33), 1314 III (1, 46). LESSER ANTILLES: ZMUC Dana 1181 III (1, 32), 1181 V (4, 34-37), 1181-2000 (1, 32), 1182 II (3, 30-37), 1184 III (1, 30), 1283 IV (16, 11-30), 1284 IV (1, 18), 1286 II (3, 17-20), 1287 II (1, 40). UMML 27873 (1,45). UMML Pillsbury 475 (1,45). VENEZUELA: UMML Carib 3-T1-B (1,39), 3-T1-D (2,46-53). PANAMA: UMML Pillsbury 373 (1, 53). YUCATAN CHANNEL: ANSP 156172 (54, 5-9). SURINAME: ZMUC Dana 1178 I (1, 48), 1178 II (4, 34-39). FRENCH GUIANA: ZMUC Dana 1174 II (13, 35-49). BRAZIL: ZMUC Dana 1173 II (3, 47-51). CENTRAL ATLANTIC: ZMUC Dana 1363 IV (1,45). Species A5 Dysommidae Type II. Smith, 1974: 673. Keller, 1976: 43.

Distinctive Characters. This leptocephalus has more myomeres (170-174) than Dysomma anguillare (118-128) and fewer than D. brevirostre (193-205). Description. Total myomeres 170-174 (n = 10), preanal myomeres 92-97 (9). Caudal-fin rays 14 (1). Proportions as % of SL: preanal 62-81 (9), HL 11-16 (9), greatest depth 8-13 (10). Keller (1976:43, fig. 4) noted two small ventral protrusions of the gut near the anterior end. Pigmentation. Dendritic melanophores on gut, 3-4 melanophores in line with these behind anus. A few small melanophores on lower body wall. Size. The largest specimen examined was 82 mm SL (MCZ 64870). Distribution. Straits of Florida, Virgin Islands, central and southern Caribbean. Study Material. Ten specimens, 20-82 mm SL. STRAITS OF FLORIDA: MCZ 64870 (1, 82), 25°31'N, 79°46'W, 195-205 m, 25 June 1966. UMML Gerda286 (1, 47), 24°03'N, 81°05'W, 0-600 m, 2 Apr. 1964. VIRGIN ISLANDS: ZMUC Dana 1196 II (1, 22), 17°43'N, 64°56'W, 600 mwo, 4 Jan. 1922. 1198 III (1, 21), same, 500 mwo. 1257 III (1, 38), same, 800 mwo, 6 Mar. 1922. 1273 II (2, 45-46), same, 24 Mar. 1922. 1273 VII (1, 30), same, 900

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mwo. VENEZUELA: UMML Carib 3-T1-D (1,31), 11°59'N, 65°29'W, 0-100 m, 16 Jan. 1968. CENTRAL CARIBBEAN: ZMUC Dana 1214 III (1, 20), 14°21'N, 76°50'W, 600 mwo, 26 Jan. 1922.

Dysomma brevirostre (Facciola, 1887) Todarus brevirostris. Grassi, 1912:18; 1913: 170, pi. 10, figs. 1-17. D'Ancona, 1931: 123, fig. 102. Nettodarus brevirostris. Blache et al., 1970: 322, figs. 7-8. Blache, 1977: 187, fig. 64. Smith, 1974: 674.

Distinctive Characters. This leptocephalus has more myomeres than the other western Atlantic members of the group (193-205 vs 118-174). Description (including data from Blache et al., 1970; Blache, 1977). Total myomeres 193-205 (n = 4), preanal myomeres 73-79 (4), predorsal myomeres 43 (1), LVBV 67-73 (2). Proportions as % of SL: preanal 50-67 (4), predorsal 34-52 (2), HL 11-15 (4), greatest depth 10-14 (3). Pigmentation. Dendritic melanophores on intestine, 2-3 in line with these behind anus. Small melanophores on anal-fin rays. Size. The largest specimen examined was 72 mm SL (ZMUC Dana 4062 II). Identification. The leptocephalus of Dysomma brevirostre was identified from the Mediterranean by Grassi (1912, 1913) through metamorphic specimens. Distribution. Dysomma brevirostre occurs in the eastern and western Atlantic and Hawaii, but leptocephali have been collected only in the Mediterranean and at two places on the coast of Africa. Study Material. Three specimens, 21-72 mm SL. ATLANTIC MOROCCO: ZMUC Dana 1111 I (1, 21), 35°04'N, 6°54'W, 300 mwo, 16 Sept. 1921. MEDITERRANEAN: ZMUC Dana 4062 II (1, 72), 36°40'N, 17°40'E, 600 mwo, 12 May 1930.4119 XVII (1,66), 40°13'N, 12°06'W, 600 mwo, 30 May 1930.

GROUP B Characters. Head and snout long; rostral filament absent; conspicuous midlateral melanophores present. Composition. About 11 species have been dis-

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Fishes of the Western North Atlantic, Part 9

lOmm

B

Imm FIGURE 714. Ilyophinae species Bs: UMML Pillsbury 1152, 69 mm SL, Hispaniola (from Smith, 1974: fig. 2). A. Whole view. B. Anal region.

tinguished, of which three occur in the Atlantic. None is identifiable with an adult. Species B5 Figure 714 Dysommidae Type III. Smith, 1974: 674, fig. 2.

Distinctive Characters. This leptocephalus has fewer myomeres than the other western Atlantic members of the group (141-149 vs ca 173-177). Description. Total myomeres 141-149 (n = 4), preanal myomeres 54-58 (5), predorsal myomeres ca 39 (1), LVBV ca 53 (1). Caudal-fin rays 13-14 (3). Proportions as % of SL: preanal 46-57 (4), predorsal 34 (2), HL 9-14 (4), greatest depth 13-20 (4). Pigmentation. Dendritic melanophores on gut. Four or five dendritic melanophores on midlateral line, beginning near anus, centered beneath surface and extending out onto body wall, sometimes only on one side. Melanophores behind

eye around brain, at angle of lower jaw, between nasal capsules and along olfactory nerve, at tip of snout and lower jaw. Size. The largest premetamorphic specimen examined was 68 mm SL (UMML Pillsbury 1152). An early metamorphic specimen was 65 mm (UMML Silver Bay 5181). Identification. The metamorphic specimen was described and illustrated by Smith (1974: 675). The definitive characters it shows indicate that it does not belong to any known species. Distribution. Bahamas, Bermuda, West Indies. Study Material. Six specimens, 30-68 mm SL. BERMUDA: UMML Pillsbury 153 (1, 64), 30°28'N, 66°52'W, 0-1250 m, 5 Aug. 1964. BAHAMAS: UMML ONR TOTO 11-4 (1, 41 + ), 24°36.8'N, 77°21.5'W, 0-722 m, 20 June 1962. HISPANIOLA: UMML Pillsbury 1152 (1, 68), 20°11'N, 70°48'W, 0-800 m, 15 Jan. 1970. UMML Silver Bay 5181 (1, (65 metamorphic), 18°50'N, 68°13.5'W, 0-600 m, 16 Oct. 1963. VIRGIN ISLANDS: ZMUC Dana 1281VII (1,32), 17°43'N, 64°56'W, 1000 mwo, 1 Apr. 1922. LESSER ANTILLES: ZMUC Dana 1181 V (1, 30), 13°07'N, 57°20'W, 1000 mwo, 21 Nov. 1921.

Synaphobranchid Leptocephali

691

FIGURE 715. Ilyophinae species C,: UMML Pillsbury 817, 44 mm SL, Puerto Rico; head (from Smith, 1974: fig. 8). Species B7 Dysommidae Type IV. Smith, 1974: 675.

Distinctive Characters. This leptocephalus has more total myomeres than species B5 (ca 173 vs 141-149) and fewer preanal myomeres than species Bn (62 vs 75-78). Description. Total myomeres ca 173 (n = 1), preanal myomeres 62 (1), caudal-fin rays ca 12 (1). Proportions as % of SL: preanal 49 (1), HL 14 (1), greatest depth ca 12 (1). Pigmentation. Dendritic melanophores along gut and an indeterminate number in line with these behind anus. Five dendritic melanophores along midlateral line, arranged as in species B5. Pigment behind eye around brain. Size. The single known specimen is 37 mm SL. Distribution. Off the Caribbean coast of Colombia. Study Material. One specimen, 37 mm SL. COLOMBIA: UMML Pillsbury 373,9°53'N, 76°20.2'W, 200 m, 14 July 1966.

Species Bn Distinctive Characters. This leptocephalus has more total myomeres than species B5 (ca 175-177 vs 141-149) and more preanal myomeres than species B? (75-78 vs 62). Description. Total myomeres ca 175-177 (n = 4), preanal myomeres 75-78 (4). Proportions as % of SL: preanal 58-71 (4), HL 14-15 (4), greatest depth 10-12 (4). Pigmentation. Dendritic melanophores along

gut. Midlateral pigment present but pattern uncertain due to faded condition of specimens. Size. The largest specimen examined was only 31 mm SL (ZMUC Dana 1260 III). Distribution. Virgin Islands and Puerto Rico. Study Material. Four specimens, 21-31 mm SL. PUERTO RICO: ZMUC Dana 1260 II (1, 30), 18°35'N, 66°00'W, 800 mwo, 8 Mar. 1922. 1260 III (1, 31), same, 600 mwo. VIRGIN ISLANDS: ZMUC Dana 1198 III (1, 21), 17°43'N, 64°56'W, 500 mwo, 4 Jan. 1922. 1253 II (1, 26), same, 600 mwo, 2 Mar. 1922.

GROUP C Characters. Stout, relatively rigid rostral filament present, long or short, often bearing a pair of teeth at its tip; head long or short; no midlateral pigment. Composition. Seven species have been distinguished, four in the Indo-Pacific and three in the Atlantic. The rostral filament in this group varies from a short extension of the rostral cartilage to a long, swordfish-like appendage. In one IndoPacific form the filament bears a series of slender tendrils. Species Q Figure 715 Dysommidae Type V. Smith, 1974: 680, fig. 8. Keller, 1976: 48, fig. 6.

Distinctive Characters. Head and snout elongate; rostral filament short, between one-quarter and one-half HL; preanal myomeres 68-73.

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A

B

FIGURE 716. Leptocephalus rostratus: whole view and head (traced from Schmidt, 1909a: pi. 1, figs. 4, 5).

Description. Total myomeres 152-158 (n = 18), preanal myomeres 68-73 (16), predorsal myomeres 40-48 (10), LVBV 69-72 (5), caudal-fin rays 14 (1). Proportions as % of SL: preanal 51-68 (16), predorsal 36-42 (11), HL 9-15 (18), greatest depth 10-17 (18). Of HL: rostral filament 21-57 (11). Head and snout long. Rostral filament short, between one-quarter and one-half HL. Keller (1976:48, fig. 6) described a strange, forked "lurelike" structure suspended from the anterior end of the roof of the mouth. One branch appears to be broken, and the other bears a swelling that resembles a cluster of grapes. Its nature and function are unknown. It was not present on any of the specimens examined here. Pigmentation. Dendritic melanophores along gut. Small melanophores on anal-fin rays. Melanophores behind eye, pigment near tip of lower jaw. Size. The largest specimen examined was 54 mm SL (ZMUC Dana 1174 II). Distribution. Southeastern Gulf of Mexico, West Indies, around Bermuda, off the Guianas, and in the South Atlantic. Study Material. 17 specimens, 19-54 mm SL. BERMUDA AND VICINITY: ZMUC Dana 1332 II (1, 43), 26°58'N, 56°58'W, 600 mwo, 5 May 1922. 1334 II (1, 43), 27°28'N/ 59°29'W, 600 mwo, 7 May 1922. 1336 III (1, 45), 28°15'N/ 63°40'W, 300 mwo, 9 May 1922. 1341II (1, 43), 34°00'N/ 68°20'W/ 600 mwo, 14 May 1922. GULF OF MEXICO: TCWC Alaminos 7 (1, 35), 22°58'N/ 85°03'W, 0-500 m, 10 May 1973. PUERTO RICO: ZMUC Dana 1260 II (1, 45), 18°35'N, 66°00'W, 800 mwo, 8 Mar. 1922. UMML

Pillsbury 817 (1, 44), 19°38'N, 67°19'W, 28-29 Jan, 1969, VIRGIN ISLANDS: ZMUC Dana 1186 (1, 48), 17°54'N, 64°54'W/ 30 Nov. 1921.1188 III (1,19), 17°43.7'N, 64°57'W/ 600 mwo, 7 Dec. 1921.1266 III (1,36), 17°45'N, 64°55.5'W, 600 mwo, 13 Mar. 1922.1280 III (1,47),17°43'N, 64°56'W/ 600 mwo, 31 Mar. 1922. LESSER ANTILLES: ZMUC Dana 1185IX (1, 45), 17°41'N, 60°58'W, 800 mwo, 27 Nov. 1921. GUIANAS: ZMUC Dana 1174 II (1,54), 5°35'N, 51°08'W, 600 mwo, 16 Nov. 1921. 1178 II (2, 34-35), 10°24'N, 54°38'W/ 600 mwo, 19 Nov. 1921. SOUTH ATLANTIC: MCZ 64492 (1, 45), 34°08'S, 42°49'W/ 200-215 m, 6 Apr. 1971. 64493 (1, 46), 33°00'S, 26°56'W/ 160-175 m, 13 Apr. 1971. 64499 (1, 51), 34°09'S, 42°53'W/ 75-80 m, 6 Apr. 1971. Species C2 Dysomminae Type VIII. Keller, 1976: 53, fig. 9.

Distinctive Characters. Like species Q, this leptocephalus has a long head and apparently a short rostral filament. It has significantly more preanal myomeres, however (89 vs 68-73). Description (from Keller, 1976). Meristic characters: total myomeres 161 (n = 1), preanal myomeres 89 (1). Head and snout long. The single specimen of this species has a short rostral filament, but Keller was uncertain whether it was intact or broken. Pigmentation. Dendritic melanophores along gut. Two melanophores on surface of brain behind eye, one above pectoral fin. Size. 45 mm SL. Distribution. Bermuda. Study Material. None.

Synaphobranchid Leptocephali Leptocephalus restrains Schmidt, 1909 Figure 716 Leptocephalus rostratus Schmidt, 1909a: 5, pi. 1, figs. 4-5 (original description, eastern North Atlantic, two syntypes ZMUC).

Distinctive Characters. This is an impressive leptocephalus, large and with a long, stout rostral filament more than twice the HL. The other members of this group known from the Atlantic have a short filament. Description. Total myomeres 186 (n = 2), preanal myomeres 102-103 (2), predorsal myomeres 92 (1), LVBV 90 (1). Proportions as % of SL: preanal 61-66 (3), predorsal 55 (1), HL 7-9 (3), greatest depth 10 (2), rostral filament 16-18 (3). Of HL: rostral filament 220-260 (3). (Schmidt gave 188191 myomeres and 15 caudal-fin rays for the two syntypes.) Head short. Rostral filament long and stout. Pigmentation. Dendritic melanophores along gut. Three or four pigment spots on underside of rostral filament. Size. This is the largest of the known ilyophine leptocephali. The two syntypes measured 212 and 213 mm "from the tip of the tail to the point of the under jaw/7 242 and 246 mm "from the tip of the tail to the point of the snout" (Schmidt, 1909a: 5). By the point of the snout, Schmidt obviously meant the tip of the rostral filament. Remarks. Schmidt described this leptocephalus from two specimens: one of 212 mm tail-to-lower-jaw length from Thor station 80, and one of 213 mm from station 178. Neither can be located at the ZMUC today. There is a specimen of 173 mm SL that has labels from both stations 80 and 178 in the vial, and a 100-mm specimen labeled station 80. Neither of these specimens was mentioned by Schmidt. He did refer in a footnote to a third specimen collected by the Thor in 1909, station 74, but this specimen cannot be found either. The problem is somewhat complicated by the fact that Thor stations were numbered separately for each cruise or expedition rather than consecutively as was done later for the Dana and Margrethe stations. Thus the same Thor number may refer to different stations depending on when it was made.

693

Distribution. Eastern North Atlantic between Europe and the Azores. Etymology. Latin rostratus (beaked), in reference to the rostral filament. Study Material. Three specimens, 100-181 mm SL. The Thor stations given here are those from 1906. EASTERN ATLANTIC: ZMUC Thor 80 (1,100), 51°34'N, 11°50'W, 200 mwo, 17 June 1906. 178 (?) (1,173), 48°04'N, 12°40'W, 1800 mwo, 2 Sept. 1906. ZMUC Dana 4173 III (1, 181), 40°46'N, 18°30'W, 400 mwo, 3 June 1931.

GROUP D Characters. Rostral filament slender, whiplike, not toothed, sometimes bearing a complex structure at its tip; head short; conspicuous lateral pigment present. Some species have one or two superficial, horizontally elongate melanophores located on the ventral margin of the myomeres slightly ahead of the anus. These will be referred to here as ventrolateral melanophores. Composition. Approximately 11 species can be distinguished, four in the Indo-Pacific and seven in the Atlantic. They are characterized primarily by the nature of the pigmentation. Leptocephalus proboscideus Lea, 1913 Figure 717 Leptocephalus proboscideus Lea, 1913: 33, fig. 25, pi. 5, no. 1 (original description, 34°59'N, 33°01'W, holotype ZMUB). Smith, 1974: 676, figs. 4-6. Keller, 1976: 46, fig. 5.

Description. Total myomeres 128-134 (n = 12), preanal myomeres 72-79 (11), predorsal myomeres 69 (2), LVBV 59-62 (5), caudal-fin rays 13 (1). Proportions as % of SL: preanal 64-71 (11), predorsal 59-61 (2), HL 9-12 (12), greatest depth 19-24 (10). Keller (1976: 44) reported 127-133 myomeres in 11 specimens from Bermuda. Pigmentation. Approximately eight pigment spots along midlateral line from shortly behind head to shortly behind anus; most of these short and subcutaneous, but two of them near midbody superficial and horizontally elongate. One or two ventrolateral melanophores, their number sometimes different on the two sides. Me-

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10 mm

B

FIGURE 717. Leptocephalus proboscideus: UMML Pillsbury 824, 67 mm SL, Virgin Islands (from Smith, 1974: fig. 4). A. Whole view. B. Head.

lanophores behind eye around brain, pigment around base of rostral filament and at tip of lower jaw. Three or four dark bands on rostral filament. Size. The largest specimen examined was 85 mm SL (UMML Pillsbury 477). Three metamorphic specimens were 70-83 mm SL, but their identity as L proboscideus is uncertain (see below). Variation. Leptocephalus proboscideus represents either a highly variable species or a complex of several closely related species. A number of specimens exist that differ in consistent ways from the specimens described above. Whether these specimens simply reflect the variability of L proboscideus or represent distinct species is uncertain. The differences are mainly in pigmentation, but some meristic variation occurs as well. These specimens will be described separately below and designated according to the system of Smith and Castle. One specimen (ZMUC Dana 1153 VI) lacks the ventrolateral pigment. Identification. I earlier (Smith 1974:676-679, figs. 5-6) described two metamorphic specimens

(UMML Gerda 341 and 961) that appeared to be L proboscideus and pointed out certain resemblances to Dysommina rugosa. I refrained from changing the name, however, because the composition of the family was still poorly known. Robins and Robins (1976: 264) agreed that the metamorphic specimens were D. rugosa but expressed doubt that L proboscideus was the same. This caution seems to have been well founded. The Ilyophinae is still not well known, and the variety of leptocephali of the L proboscideus type is greater than had been suspected. The conspicuous brown spots on the dorsal and anal fins of the metamorphic specimens are particularly puzzling because they do not appear in the premetamorphic leptocephali, although one of the related specimens described below has them. I speculated then that these spots might appear only at metamorphosis. That may still be true, but so many uncertainties exist that a conclusive identification cannot be given. It can only be said that Leptocephalus proboscideus may be the leptocephalus of Dysommina or something similar to Dysommina.

Synaphobranchid Leptocephali Remarks. Keller (1976: 46, fig. 5) described and illustrated a peculiar lure-like structure at the tip of the rostral filament of one of the Bermuda specimens. This structure has not been reported before and was not present in specimens examined here, but it is undoubtedly delicate and easily damaged. Keller speculated that it might be used as a lure, although leptocephali do not appear to be predaceous. She also described a "small, darkly pigmented structure extending downward from the roof of the mouth near the base of the rostral filament." This structure, too, has not been reported previously and was not apparent in the specimens examined here. Distribution. Gulf Stream, Straits of Florida, West Indies, central Caribbean, and across the central Atlantic from Bermuda to the Azores and nearly to the Canary Islands. The smallest specimen came from the Gulf Stream off Florida (UMML Pillsbury 95), and the metamorphic specimens (if indeed they belong to this species) came from the Straits of Florida (UMML Gerda 341 and 961) and the Azores (ZMUC Dana 4190 I). Etymology. From the Latin proboscis (snout), in reference to the rostral filament. Study Material. 14 specimens, 29-85 mm SL. BERMUDA: ZMUC Dana 857-100 (1, 48), 30°47'N, 62°47'W/100 mwo, 13 June 1920. SARGASSO SEA: ZMUC Dana 1330 III (1, 45), 26°37'N, 54°45'W, 600 mwo, 4 May 1922. GULF STREAM: UMML Pillsbury 95 (1,29), 28°46'N, 79°38'W, 0-100 m, 26 July 1964. VIRGIN ISLANDS: ZMUC Dana 1296 I (1, 60), 17°43'N, 64°56'W, 1000 mwo, 19 Apr. 1922. UMML Pillsbury 824 (1, 67), 19°32'N, 65°21'W, 02650 m, 2 Feb. 1969. LESSER ANTILLES: UMML Pillsbury 477 (1, 85), 12°59.3'N, 61°38.2'W, 0-1100 m, 2 Aug. 1966. CENTRAL CARIBBEAN: ZMUC Dana 1215-1200 (1, 76), 16°06'N, 76°02'W, 1200 mwo, 27 Jan. 1922. CENTRAL ATLANTIC: ZMUC Margrethe 1017-300 (1, 49), 28°00'N, 37°57'W, 300 mwo, 3 Sept. 1913. 1030 (1, 49), 35°31'N, 55°58'W, 300 mwo, 1 Oct. 1913. ZMUC Dana 1363 III (1, 48), 30°25'N, 44°46'W, 300 mwo, 7 June 1922. CANARY ISLANDS: ZMUC Dana 1153 VI (1,52), 28°48'N, 20°45'W, 400 mwo, 23 Oct. 1921. Metamorphic Specimens (identity questionable). STRAITS OF FLORIDA: UMML Gerda 341 (1,70), 25°51'N, 79°25'W, 0-460 m, 24 July 1964. 961 (1, 79), 23°47'N, 82°00'W, 2000 mwo, 31 Jan. 1968. ZMUC Dana 4190 I (1, 83), 37°58'N, 27°39'W, 500 mwo, 14 June 1931.

695

Species D3 Distinctive Characters. This leptocephalus differs from L. proboscideus primarily in lacking ventrolateral pigment and having the midlateral pigment series extending more posteriorly. Midlateral melanophores are usually all short and subcutaneous. Myomeres are more numerous than in L. proboscideus (135-138 vs 128-134). Description. Total myomeres 135-138 (n = 4), preanal myomeres 77-79 (4), predorsal myomeres 70 (1). Proportions as % of SL: preanal 6273 (4), predorsal 58 (1), HL 8-12 (4), greatest depth 20-24 (4). Pigmentation. Similar to that of L. proboscideus, but ventrolateral pigment absent and series of midlateral melanophores extends farther back. Midlateral melanophores usually all subcutaneous and not elongate. One specimen has dark spots on dorsal and anal fins. Four or five dark bands on rostral filament. Size. The specimens examined were 31-86 mm SL. Remarks. The most obvious difference between this leptocephalus and the typical L. proboscideus is the pigmentation, but it is not entirely consistent. Ventrolateral melanophores are characteristic of L proboscideus, but one specimen lacks them (ZMUC Dana 1153 VI). All of the D3 leptocephali lack ventrolateral pigment, but only four specimens are available. All of the L. proboscideus examined had at least two midlateral melanophores that were superficial and horizontally elongate. In three of the four specimens of species D3 all the midlateral melanophores were deep-lying and short. The two forms also differ in myomere number, and they are largely separated geographically. Leptocephalus proboscideus is found in the western and central Atlantic, whereas species D3 occurs in the eastern Atlantic. Still, it is difficult to place individual specimens. The specimen of L. proboscideus that lacks ventrolateral melanophores is also the easternmost record of that species. Its myomere count is ambiguous (134). Is it an L. proboscideus without ventrolateral pigment or a species D3 with elongate midlateral melanophores?

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DO

AD

FIGURE 718. Ilyophinae species D4: 81 mm SL (from Keller, 1976: fig. 7).

One specimen (ZMUC Dana 4190 VIII) has a series of dark spots on the dorsal and anal fins like those of the putative metamorphic L. proboscideus (Smith, 1974: 677, fig. 5). It is the largest specimen, 86 mm SL, which may be further evidence that the character appears at or near metamorphosis. Distribution. The Azores and Madeira. Study Material. Four specimens, 31-86 mm SL. AZORES: ZMUC Dana 1379 III (1,31), 38°02'N, 25°52'W, 600 mwo, 18 June 1922.4190 VIII (1,86), 37°58'N/ 27°39'W, 300 mwo, 14 June 1931. MADEIRA: ZMUC Dana 1142 I (2, 41), 33°26'N, 16°59'W, 600 mwo, 15 Oct. 1921.

Species D4 Figure 718 Dysomminae Type VI. Keller, 1976: 48, fig. 7.

Distinctive Characters. This leptocephalus is distinguished by a short series of melanophores immediately above and below the midlateral line slightly before the level of the anus. Unlike L proboscideus, it has only one midlateral melanophore that is superficial and elongate. Description (from Keller, 1976). Total myomeres 128-133 (n = 9). Pigmentation. Similar to that of L. proboscideus but only one midlateral melanophore superficial and elongate. In addition, a short longitudinal series of 3-5 melanophores above and below midlateral line near superficial midlateral melanophore. Some pigment developing on anal fin. Remarks. Keller described this leptocephalus from nine specimens collected near Bermuda.

The myomere counts are identical to those of L proboscideus, but the two forms are easily distinguished by the pigmentation. This could be part of the variation of L proboscideus, but the extra lateral pigment was not seen in any of the 14 specimens of that species examined by me. Keller herself recorded 12 specimens of typical L proboscideus from the same collections, all without the extra lateral pigment. Distribution. Bermuda. Study Material. None.

Species D5 Dysomminae Type VII. Keller, 1976: 51, fig. 8.

Distinctive Characters. This leptocephalus resembles the previous one in having some melanophores above and below the midlateral line, but the anterior five midlateral melanophores are superficial rather than deep. The single known specimen has distinctly fewer myomeres than either Leptocephalus proboscideus or species D4. Description. Total myomeres 124 (n = 1), preanal myomeres 70 (1). Pigmentation. Nine midlateral pigment spots: first five small and superficial; sixth and seventh, near anus, larger and deeper; last two small and deep-lying. One ventrolateral melanophore. Extra lateral pigment above and below midlateral line. Dendritic melanophores along gut, and two pigment spots on anal fin. Distribution. Bermuda. Study Material. None.

Synaphobranchid Leptocephali

697

10 mm FIGURE 719. Leptocephalus dolichorhynchus: UMML Gerda 496, 26 mm SL, Bahamas (from Smith, 1974: fig. 7).

Leptocephalus dolichorhynchus Lea, 1913 Figure 719 Leptocephalus dolichorhynchus Lea, 1913:34, figs. 26-27, pi. 5, no. 2 (original description, 34°59'N, 33°01'W and 40°17'N, 50°39'W, three syntypes ZMUB). Smith, 1974: 679, fig. 7.

Distinctive Characters. Leptocephalus dolichorhynchus differs from the preceding leptocephali in that the midlateral melanophores are all superficial and begin more posteriorly. There is no ventrolateral pigment and no extra lateral pigment. Description (including data from Lea, 1913). Total myomeres 128-136 (n = 3), preanal myomeres 61-71 (4). Proportions as % of SL: preanal 67-71 (4), HL 9-12 (4), greatest depth 15-17 (4). Pigmentation. Dendritic melanophores along gut. Five or six superficial, dendritic melanophores on or just below midlateral line, beginning near midbody, sometimes restricted to one side. A few small melanophores behind anus and below myomeres. Melanophores behind eye, on lower jaw, and at base of rostral filament. Size. The four known specimens are 24-33 mm SL. Variation. Lea recorded 61 preanal myomeres for one of his syntypes, a value substantially lower than those of the other three specimens (72-75). Distribution. Known from three localities: southwest of the Azores, the Gulf Stream south of the Grand Banks, and the northern Bahamas. Etymology. From the Greek dolichos (long) and rhynchos (snout), in reference to the rostral filament.

Study Material. One specimen, 26 mm SL. BAHAMAS: UMML Gerda 496, 26°42'N, 79°01'W, 103 m, 3 Feb. 1965.

Species D7 Distinctive Characters. This leptocephalus has significantly fewer myomeres than any other in the group (117-119 vs 124-138). In addition, midlateral melanophores are more numerous (13 vs 8-10). Description. Total myomeres 117-119 (n = 4), preanal myomeres 65-68 (4), LVBV 58 (1). Proportions as % of SL: preanal 63-72 (4), HL 11-13 (4), greatest depth 16-21 (4). One specimen (ZMUC Dana 857) has two pairs of tendrils on rostral filament. Pigmentation. Dendritic melanophores on gut, sometimes three melanophores in line with these behind anus. About 13 midlateral melanophores, none horizontally elongate. No ventrolateral pigment or extra lateral pigment. Small spots on base of anal fin. Four dark bands on rostral filament. Size. 21-54 mm SL. Distribution. Bermuda and the West Indies. Study Material. Four specimens, 21-54 mm SL. BERMUDA: ZMUC Dana 857-50 (1, 54), 30°47'N, 62°27'W, 50 mwo, 13 June 1920. BAHAMAS: ZMUC Dana 1243 II (2, 21), 21°04'N, 73°48'W, 600 mwo, 16 Feb. 1922. HISPANIOLA: ZMUC Dana 1245 II (1, 31), 19°35'N, 73°27'W, 600 mwo, 17 Feb. 1922.

Species Dn Distinctive Characters. This leptocephalus differs from L. proboscideus in lacking ventrolateral

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Fishes of the Western North Atlantic, Part 9

melanophores and in having none of the midlateral melanophores horizontally elongate. It differs from species D4 and D5 in lacking the extra pigment above and below the midlateral series. It differs from L dolichorhynchus in having the midlateral melanophores deep rather than superficial. It differs from species D3 in having fewer preanal and total myomeres (71 and ca 127 vs 77-79 and 135-138). It differs from species D7 in having more preanal and total myomeres (71 and ca 127 vs 65-68 and 117-119) and fewer midlateral spots (10 vs 13). Description. Total myomeres ca 127 (n = 1), preanal myomeres 71 (1). Midlateral pigment spots at myomeres 19-20, 28-29, 30-31, 39-40,

41-42, 52-53,61-62, 68-69, 80-81, 93-94. Proportions as % of SL: preanal 77 (1). Pigmentation. Dendritic melanophores on gut, none behind anus. Ten midlateral spots centered on myosepta, all short and deep-lying although some extend to surface. Pigment at tip of upper and lower jaw, and just behind angle of lower jaw. Size. The only known specimen is 22 mm SL. Distribution. The specimen was taken in the Gulf Stream off St. Augustine, Florida. Study Material. One specimen, 22 mm SL. GULF STREAM: MCZ 65172 (1, 22), 29°56'N, 78°57'W, 350-0 m, 15 Feb. 1979.

Family Moringuidae: Leptocephali D A V I D G. SMITH

Characters. Small leptocephali, maximum SL 60-70 mm. Body moderately deep, depth about a quarter to a third SL; tail moderate. Gut moderately short, anus near two-thirds SL; a prominent arch or loop just before anus, capped by one or a few expanded melanophores; stomachliver-gall bladder located posteriorly, shortly before intestinal loop. Dorsal fin moderately short, beginning above, slightly behind, or slightly before level of anus. Head and snout moderate. One to several expanded melanophores on dorsal surface of intestinal loop, sometimes a smaller melanophore on anterior part of esoph-

agus. Lateral pigment, when present, consists of one to several stellate melanophores on midlateral line, often unequal in number on two sides of body. Some pigment usually present on head. Composition. The two genera of moringuids differ mainly in pigmentation. Leptocephali of Moringua have several large, stellate melanophores on the midlateral line, distributed unequally on the two sides of the body. Leptocephali of Neoconger are either without lateral pigment or have a single, smaller melanophore on the midlateral line near the tail.

KEY TO THE MORINGUID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC

la. Several midlateral melanophores; myomeres 110-124 Moringua edwardsi, p. 699 Ib. No more than one lateral melanophore, near tail; myomeres 93-110 2 2a. Lateral melanophore present; predorsal myomeres 39-56, approximately 4-8 fewer than preanal myomeres Neoconger mucronatus, p. 701 2b. Lateral melanophore absent; predorsal myomeres 57-62; difference between number of predorsal and preanal myomeres three or less Neoconger sp., p. 702 Moringua edwardsi (Jordan and Bollman, 1889) Figure 720

115-138 (26). Proportions as % of SL: preanal 7379 (6), HL 8-11 (7), greatest depth 17-23 (7). Pigmentation. Approximately 7-8 large, stellate melanophores on midlateral line, alternately on two sides of body, at more or less regular intervals from head to tail. A stellate melanophore dorsally on intestinal loop. Small melanophores around nasal capsule, on lower jaw, and behind eye. Size. Maximum size slightly more than 50 mm SL (Castle, 1979: 5). Variation. The species of Moringua are the only eels known to show sexual dimorphism in the number of vertebrae. Adult males of Moringua

Leptocephalus diptychus Eigenmann and Kennedy, 1901: 830, fig. Moringua edwardsi. Eldred, 1968a: I, fig. 1. Karmovskaya, 1975: 93. Keller, 1976: 100. Castle, 1979. Smith, 1979: 11, fig. 10.

Distinctive Characters. Several stellate melanophores on midlateral line. Description (mainly from Castle, 1979: 5). Total myomeres 110-124 (n = 588), preanal myomeres 72-82 (98), predorsal myomeres 79-87 (23), LVBV 70-79 (21), anterior margin of gall bladder 55-63 (21), dorsal-fin rays 115-137 (26), anal-fin rays 699

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Fishes of the Western North Atlantic, Part 9

FIGURE 720. Moringua edwardsi: MBI 486, 37 mm SL, Yucatan Channel (B, C from Smith, 1979: fig. 10). A. Whole view. B. Head. C. Intestinal loop.

edwardsi have 109-117 vertebrae (x = 112.6), and females have 116-123 (x = 119.4) (Castle and Bohlke, 1976: 617). Myomere counts of leptocephali show a similar bimodality, with peaks at 113-114 and 119-120 (Castle, 1979: 5). Identification. Castle (1965a) identified leptocephali of Moringua from the Indo-West Pacific through metamorphic specimens. Eldred (1968a) identified similar leptocephali from the western Atlantic as Moringua edwardsi. Spawning and Growth. Castle (1979: 9) found that Moringua edwardsi spawns around the West Indies and Bermuda, the same area inhabited by adults. Spawning appears to go on throughout the year, perhaps with a monthly periodicity related to lunar cycles (Castle, 1979: 13). By following the change in size distribution of leptocephali collected around the Virgin Islands between December and March, Castle (1979: 13) was able to estimate the duration of larval life as approximately 3% months and the average growth rate as about 3 mm per week. Remarks. See p. 68 for a discussion of the type

specimens of Leptocephalus diptychus Eigenmann and Kennedy. Distribution. Primarily the Caribbean and West Indian region, extending to the Straits of Florida, the Bahamas, the Gulf Stream, Bermuda, and the Sargasso Sea; present but not common in the Gulf of Mexico. There are no records from east of the Lesser Antilles off the Guianas or Brazil. The only records from east of 60°W are north of 20°N, where they could have been carried by prevailing currents. Study Material 127 specimens, 7-48 mm SL. BAHAMAS: ANSP154001 (1,19), 154019 (1,30), 155818 (1, 12), 155819 (9, 13-42), 155820 (2, 17-30), 155821 (4, 15-28), 155822(4,28-35), 155823 (2,18-42). UMML Pillsbury 170 (1, 48). STRAITS OF FLORIDA: ANSP 154003 (1, 35), 154344 (1, 29), 154397 (1, 38). UMML Gerda 98 (1, 38). GULF OF MEXICO: ANSP 155799 (1, 21). YUCATAN CHANNEL: ANSP 155790 (1, 45), 155791 (2, 930), 155792 (1, 30), 155793 (1, 34), 155794 (1, 40), 155795 (1, 34), 155796 (3, 10-21), 155797 (1, 32), 155798 (4, 1129), 155800 (1, 25), 155801 (2, 7-8), 155802 (12, 29-39), 155803 (6,33-36), 155804 (1,15), 155805 (2,39-44), 155806 (5, 14-20), 155807 (8, 19-46), 155808 (3, 27-39), 155809

Moringuid Leptocephali

701

FIGURE 721. Neoconger mucronatus: ANSP 154585, 33 mm SL, Gulf of Mexico (B from Smith, 1979: fig. 11). A. Whole view. B. Head. C. Intestinal loop.

(4, 12-30), 155810 (1, 15), 155811 (1, 25), 155812 (1, 21), 155813 ( 2, 26-37), 155814 (1, 7), 155815 (2, 25), 155816 (1, 33), 155817 (1,24), 158799 (2,22-43). MBI172 (1), 486 (2, 26-37), 483-487 (1), 488 (3, 26-34), 501 (19, 28-45).

Neoconger mucronatus Girard, 1858 Figure 721 Leptocephalus anaelisae Tommasi, 1960: 93, fig. 3-3a. Leptocephalus tuberculatus (not of Castle, 1965). Eldred, 1967c: 1, fig. 1. Karmovskaya, 1975: 93, fig. 3a. Neoconger mucronatus. Smith and Castle, 1972: 230, figs. 20a,e, 21-27. Smith, 1979: 10, fig. 11.

Distinctive Characters. A single midlateral melanophore, near tail; dorsal fin begins slightly but distinctly before level of anus, predorsal myomeres approximately 4-8 fewer than preanal myomeres. Description (some of the following data provided by Mark M. Leiby). Total myomeres 93108 (n = 108), preanal myomeres 49-60 (105), predorsal myomeres 39-56 (88), LVBV 50-59 (45), nephric myomeres 48-55 (41), lateral melanophore at myomere 79-89 (104), ventral melanophore at myomere 20-28 (40), dorsal-fin rays 134-

197 (29), anal-fin rays 125-168 (27). Proportions as % of SL: preanal 59-74 (96), predorsal 52-63 (38), HL 7-11 (85), greatest depth 20-32 (86). Pigmentation. A single, moderately small melanophore on midlateral line a short distance before end of tail. One to several expanded melanophores on dorsal surface of intestinal loop; sometimes a smaller melanophore ventrally on anterior part of gut. Small melanophores on upper and lower jaw and dorsal surface of snout. Size. The largest specimen examined was 51 mm SL (ANSP 155760). No metamorphic specimens were available, but the closely related eastern Pacific species Neoconger vermiformis metamorphoses at about 50 mm (Smith and Castle, 1972: 240). Variation. Geographic variation of leptocephali in the western Atlantic is discussed elsewhere in this work (family Moringuidae, p. 63, Table 3). Three populations are present: one in the Gulf of Mexico, one in the Caribbean and off the Guinas, and one from the extreme eastern Caribbean to Brazil. They are distinguished by meristic characters, especially the number of predorsal

702

Fishes of the Western North Atlantic, Part 9

myomeres. In addition, the Gulf of Mexico form usually lacks the anterior ventral melanophore, and the Brazilian form has a flatter intestinal loop. The specimen from the Azores and the one from the Sargasso Sea belong to the intermediate or Caribbean form. Very small specimens may lack the lateral melanophore. Identification. Smith and Castle (1972: 225) identified leptocephali of Neoconger through metamorphic specimens. Spawning and Growth. Data from a survey of the Texas coast done for the Bureau of Land Management (made available by L. Alan Collins of the National Marine Fisheries Service, Panama City, Florida) and data from the MBI collections give a good picture of the spawning and growth of Neoconger mucronatus in the Gulf of Mexico. Spawning begins in September when large numbers of small leptocephali appear. Of more than a thousand specimens collected by the BLM survey in September, all were less than 10 mm in length. Leptocephali smaller than 10 mm continued to be taken, but in declining numbers, into December. By November the maximum size had increased to about 40 mm. By February only a few stragglers were present, indicating that nearly all leptocephali had completed metamorphosis. This suggests a duration of three or foui months from hatching to metamorphosis. The pattern in the Caribbean is less clear. In the Yucatan Channel very young specimens (57 mm SL) were collected only in the summer, but moderate to large individuals (47-51 mm SL) were collected in the winter and spring, indicating an extended spawning period. Remarks. The two smallest specimens from the Yucatan Channel (5 and 7 mm SL, ANSP 155451 and 155450, respectively) are assigned to Neoconger mucronatus with some question. Both specimens lack the lateral and anterior ventral melanophores and could belong to the following species (Neoconger sp., see below). A specimen of similar size from the Gulf of Mexico (ANSP 155751, 6 mm SL) also lacks the lateral melanophore, however, and the character may simply be absent in very small leptocephali.

Distribution. Widely distributed in the western Atlantic from Brazil through the Caribbean to the Gulf of Mexico and the Straits of Florida. These leptocephali are not common in the Gulf Stream or the Sargasso Sea; the few individuals collected there undoubtedly drifted in on the currents from the Caribbean or the Florida Straits. A single specimen from the Azores (ZMUC Dana 4191, S^ISH 27°24rW) is the easternmost record (Smith and Castle, 1972: 232). Study Material 265 specimens, 5-51 mm SL. SARGASSO SEA: ZMUC Dana 889 (1, 38). BAHAMAS: UMML Pillsbury 190 (1, 33). STRAITS OF FLORIDA: ZMUC Dana 1225 (2, 33-36). UMML IK-4 (1, 44). GULF OF MEXICO: ANSP 154269 (1, 47), 154584 (18, 31-39), 154585 (1, 33), 154586 (22, 25-38), 155450 (1, 7), 155451 (1,5), 155750 (9,24-37), 155751 (26, 6-36), 155753 (1,23), 155756 (1, 32), 155757 (1, 40), 155759 (7, 23-35), 155761 (3, 28-38), 155762 (14, 7-17), 155763 (2, 30-36), 155765 (5, 31-38), 155767 (1, 43), 155768 (1, 36), 155769 (2, 3135), 155770(1,29), 155773(2,22-30), 155774(1,38), 155775 (9, 25-33), 155776 (2, 31-33), 155777 (10, 24-35), 155778 (17, 9-34), 155780 (3, 33-37), 155781 (4, 9-33), 155782 (1, 25). MBI 88 (5,25-36), 559(1), 569 (1). YUCATAN CHANNEL: ZMUC Dana 1223 (1, 45). ANSP 155752 (2, 45-47), 155754 (2,44-47), 155755 (3,38-42), 155758 (1,36), 155760 (1,51), 155764 (1, 46), 155766 (1, 43), 155771 (1,9), 155772 (1, 32), 155779 (2, 43-44). MBI 483-487 (3). JAMAICA: ZMUC Dana 1215 (1, 42). LESSER ANTILLES: ZMUC Dana 1283 (7,18-30), Dana 1287 (3, 28-35). COLOMBIA: UMML Pillsbury 383 (3, 46-51), 384 (16, 38-47). PANAMA: ZUMC Dana 3547 (5,21-40). UMML Pillsbury 343 (1,43), 427 (1,41), 440 (1,50). GUIANAS-BRAZIL: ZMUC Dana 1174 (4, 40-44), 1180 (2, 28-29), 1202 (3, 42-46). ANSP 154270 (3, 37-39), 154271 (3, 37-39), 154272 (1, 40), 154273 (2, 35-36), 154274 (9, 35-42), 154275 (1, 40). AZORES: ZMUC Dana 4191 (1, 43+).

Neoconger species Distinctive Characters. This leptocephalus differs from that of Neoconger mucronatus in lacking the lateral melanophore at all stages and in having a more posterior dorsal-fin origin. In N. mucronatus the dorsal fin begins slightly but distinctly before the anus; there are about four to eight fewer predorsal than preanal myomeres. In the present leptocephalus, the dorsal fin begins almost directly above the anus. Of the 20 specimens for which both counts were available,

Moringuid Leptocephali

six had an equal number of preanal and predorsal myomeres, eight had one or two more predorsal than preanal myomeres, five had one fewer predorsal than preanal myomeres, and one had three fewer predorsal than preanal myomeres. The total number of predorsal myomeres is also greater in this species than in N. mucronatus (57-62 vs 39-56). Description (some of the following data provided by Mark M. Leiby). Total myomeres 105110 (n = 22), preanal myomeres 56-63 (22), predorsal myomeres 57-62 (20), LVBV 57-60 (4), nephric myomeres 53-57 (16), dorsal-fin rays 140187 (9), anal-fin rays 136-195 (9). Proportions as % of SL: preanal 63-73 (19), predorsal 64-73 (14), HL 7-12 (19), greatest depth 21-30 (17). Pigmentation. Lateral and anterior ventral melanophores absent. Pigment present only on intestinal loop. Size. The largest specimen examined was 46 mm SL (University of the West Indies, Fisheries Ecology Research Project Station 7374-A-10-11B). Identification. The consistent differences between this leptocephalus and that of Neoconger mucronatus and the broad sympatry of the two

703

forms indicate that they are distinct species. Adults could probably be distinguished by the number of predorsal vertebrae, which does not seem to change much from the number of predorsal myomeres in the leptocephali (Smith and Castle, 1972). The only two adult specimens of Neoconger known from the Caribbean (ANSP 139683 and UMML 22149) have 42 and 45 predorsal vertebrae, values that seem too low for the present leptocephali. The type of Chrinorhinus torrei Howell Rivero (MCZ 32786) also came from the Caribbean, but it did not yield a readable radiograph. Spawning and Growth. There is no evidence of seasonal spawning. Specimens were collected throughout the year. Distribution. Caribbean Sea, from the Virgin Islands to Panama and the Yucatan Channel. Study Material. 22 specimens, 21-43 mm SL. CENTRAL CARIBBEAN: ZMUC Dana 1214 (1, 43). JAMAICA: University of the West Indies FERP 7374-A-1011-B (1, 46). VIRGIN ISLANDS: ZMUC Dana 1186 (2, 36-37), 1189 (1), 1192 (1), 1195 (1, 43), 1196 (1, 43), 1289 (1, 41). COLOMBIA: UMML Pillsbury 384 (1, 41). PANAMA: ZMUC Dana 1202 (1, 40), 3547 (7, 27-39). UMML Pillsbury 426 (1, 21). YUCATAN CHANNEL: ANSP 155452 (1, 22), 155453 (1, 43), 155454 (1, 31).

Family Nettastomatidae: Leptocephali D A V I D G. SMITH

bodied anteriorly, and sharply narrowed toward the tail. Two intestinal swellings are present but often reduced. The head is relatively short. Leptocephali of Hoplunnis and Saurenchelys are shallow-bodied and elongate. The two intestinal swellings are well developed, and the head is moderate to moderately elongate. Leptocephali of Facciolella are also elongate, but they lack the well defined swellings in the gut. The head is elongate and until late in development bears a short anterior extension of the rostral cartilage. The letters designating leptocephali that cannot be identified with an adult (i.e., species A, B, etc.) are those used by Smith and Castle (1982). Only the leptocephali present in the western North Atlantic are treated here. Therefore, if species B is listed but species A is not, that means that species A does not occur in the study area.

Characters. Moderate to large leptocephali, maximum size about 85-200 mm SL. Body deep to elongate, tail acute. Gut short, either with two distinct swellings or with irregular undulations, preanal length usually less than half SL; kidney linear with a prominent expansion near posterior end of gut, terminating shortly before anus; liver forming a single lobe anteriorly, often contributing to anterior swelling of gut. Dorsal fin long, originating in anterior half of body, often immediately behind head. Pectoral fin well developed but lost at metamorphosis in all but Hoplunnis. Pigment variable, but always present on gut, lateral midline, and head; additional pigment sometimes present on lower body wall. Composition. Nettastpmatid leptocephali fall into three morphologically distinct groups. Leptocephali of Nettastoma and Nettenchelys are deep

KEY TO THE NETTASTOMATID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC la. Ib. 2a. 2b. 3a.

Body depth about 10-30% SL anteriorly, narrowing markedly toward tail 2 Body uniformly shallow, depth 4-10% SL 6 Greatest depth about 24-30% SL 3 Greatest depth about 10-20% SL 4 Lateral pigment spot consists of a single, horizontally elongate element around notochord; preanal myomeres 60-70 Nettastoma melanura, p. 705 3b. Lateral pigment spot consists of a horizontally elongate element around notochord and a vertically elongate element immediately above it; preanal myomeres 53-56 Nettastoma syntresis, p. 707 4a. Three lateral pigment spots Nettenchelys sp. D, p. 710 4b. One lateral pigment spot 5 5a. Preanal myomeres 49-56 Nettenchelys pygmaea, p. 708 5b. Preanal myomeres 59-64 Nettenchelys inion or exoria, p. 709 6a. Two well developed intestinal swellings; no anterior extension of rostral cartilage 7 6b. Intestinal swellings not evident; a short anterior extension of rostral cartilage except in specimens near metamorphosis 16 7a. Stellate melanophores on lower body wall postanally 8 704

Nettastomatid Leptocephali

705

7b. No stellate melanophores on lower body wall postanally 9 8a. Melanophores on lower body wall just above ventral margin of myomeres Hoplunnis tennis, p. 710 8b. Melanophores on lower body wall below ventral margin of myomeres Hoplunnis macrura, p. 712 9a. Midlateral melanophores short, deep, and vertically elongate 10 9b. Midlateral melanophores round or horizontally elongate 13 lOa. Total myomeres 250-260; preanal myomeres 56-61; prehepatic myomeres 20-23 Hoplunnis similis, p. 715 lOb. Total myomeres fewer than 240 11 lla. Total myomeres ca 210 Hoplunnis sp. C, p. 716 12 lib. Total myomeres ca 220-235 12a. Preanal myomeres 50-54; prehepatic myomeres 17-20 Hoplunnis diomediana, p. 714 12b. Preanal myomeres 55-58; prehepatic myomeres 22-25 Hoplunnis sp. B, p. 716 13a. Kidney short and round; total myomeres 201-209 Saurenchelys cognita, p. 716 14 13b. Kidney elongate; total myomeres more than 210 14a. Total myomeres approximately 249 Saurenchelys sp. B, p. 717 14b. Total myomeres fewer than 240 15 15a. Three large, stellate, midlateral melanophores behind anus Saurenchelys sp. C, p. 718 Saurenchelys stylura, p. 719 15b. More than three large midlateral melanophores 16a. Preanal myomeres 57-61; total myomeres 240-254 Facciolella sp. B, p. 720 16b. Preanal myomeres 43-47; total myomeres 253-264 Facciolella sp. C, p. 721

Nettastoma melanura Rafinesque, 1810 Figure 722 Hyoprorus messinensis Kolliker, 1854: 101. Leptocephalus longirostris Kaup, 1856b: 150, pi. 18, fig. 1414a. Hyoprorus messanensis. Facciola, 1883a: 4; 1893: 144 (misspelling). Nettastoma melanurum. Facciola, 1893: 144 (part, first and second stages only). Grassi, 1913: 143, pi. 9, figs. 2343.D'Ancona, 1931:119, figs. 98-100. Sparta, 1942:155, pi. l,figs. 11-13. Keller, 1976: 142 (part). Blache, 1977: 172, fig. 58. Smith and Castle, 1982: 7, figs. 2-3. Leptocephalus urosema Lea, 1913: 39, fig. 33, pi. 5, no. 5. Misidentifications: Not Leptocephalus longirostris Kaup. Haast, 1875: 238. Not Nettastoma melanura Rafinesque. Facciola, 1893: 146 (part, third and fourth stages are Facciolella oxyrhynchus). Castle, 1964c: 80 (Nettastoma parviceps); 1965a: 144 (Nettastoma parviceps and Nettenchelys gephyra); 1966b: 59, figs. 4, 6 (Nettenchelys gephyra)', 1970a: 14 (identity uncertain); 1975: 25 (identity uncertain).

Distinctive Characters. Leptocephali of Nettastoma have a deeper body than those of Net-

tenchelys. Of the two species of Nettastoma in the western North Atlantic, N. melanura is distinguished from N. syntresis by having a lateral pigment spot composed of a single horizontally elongate melanophore. It also has more preanal myomeres (60-70 vs 53-56). Description. Total myomeres 186-211 (n = 20), preanal myomeres 60-70 (35), predorsal myomeres 39-48 (11), prehepatic myomeres 14-20 (3), LVBV ca 61-62 (10), lateral pigment spot begins at myomere 86-122 (35), dorsal-fin rays 356-389 (5), anal-fin rays 234-317 (7). Proportions as % of SL: preanal 44-62 (10), predorsal 35 (1), HL 9-12 (3), greatest depth 24-35 (10). Body deep, deepest point near anterior third or fourth of SL, narrowing sharply toward tail; tail acute. Gut short, preanal length about half SL. Two thickenings in gut, one anteriorly associated with liver, and one posteriorly associated with kidney; the posterior thickening reduced, often no more than a slight loop capped by kidney. Dorsal fin relatively long, begins at about anterior third of SL. Head moderate, be-

706

Fishes of the Western North Atlantic, Part 9

^ ^T^JlsaE^gi—

FIGURE 722. Nettastoma melanura (from Smith and Castle, 1982: fig. 2): A ZMUC P311668,106 mm SL. B. Same, head. C. ZMUC P311674, 31 mm SL. D. ZMUC P311669, 111 mm SL, metamorphic; head.

coming somewhat more elongate in larger individuals. Pigmentation. A single lateral pigment spot around notochord approximately midway between anus and tip of tail; spot composed of a single horizontally elongate melanophore. Melanophores ventrally and laterally on liver, laterally on posterior intestinal swelling, and between kidney and intestine. Internal pigment behind eye over lower part of brain, on rostrum and palate. Pigment on tips of both jaws. Pigment dorsal and posterior to heart. Size. Maximum size about 120 mm SL. Identification. The leptocephalus of Nettastoma melanura was identified from the Mediterranean by Facciola (1893). Spawning and Growth. Most of the specimens examined came from the eastern Atlantic and Mediterranean (Dana stations), and the seasonal coverage was insufficient to determine the spawning season and growth rate. Around Bermuda specimens were collected from March to

November (Dana; also Keller, 1976: 154). There was no obvious variation in size between seasons, indicating a prolonged spawning season. Distribution. Both sides of the tropical Atlantic, including the Mediterranean, Gulf of Guinea, Caribbean, and Gulf of Mexico. Study Material. 136 specimens, 17-121 mm SL. BERMUDA: ZMUC Dana 857-150 (1, 50), 877-150 (2, 51-53). URIZ Ocean Acre 1-31 (1, 45+), 3-5 (1, 89), 4-31 (1, 50), 6-19 C + D (1, 34), 7-17 (1, 54), 12-32 A (1, 53), 12-87 (1, 68). GULF STREAM: ZMUC Dana 1342 V (1, 43). STRAITS OF FLORIDA: ZMUC Dana 1225II (1,21). UMML Gerda 322 (1, 27). GULF OF MEXICO: ANSP 155877 (1, 36). VIRGIN ISLANDS: ZMUC Dana 952-600 (1, 18). EASTERN ATLANTIC: ZMUC Thor 26 (1, 85), 144 (1, 27), 285 (1, 17). ZMUC Dana 1108 I (1, 62), 1110 VII (1, 56), 1139 II (2, 63-66), 1142 II (1, 64), 1142 V (1, 66), 1145 V (1,63), 1145 VI (1,68), 1146II (5,64-72), 1152 VI (1,75), 1379 III (1,28), 35361 (1,57), 4019 VIII (ZMUC P311668) (1, 119), 4023 IX (1, 35), 4141 V (1, 41), 4183 I (1, 107), 4190 II (1, 40), 4191 VI (1, 113), 4192 VI (1, 34), 4193 VII (1, 24). MEDITERRANEAN: ZMUC Dana 4036 XIII (1, 89), 4040 IV (2, 85-121 + ), 4050 II (1, 86), 4050 XIII + XVII (1, 35), 4050 VIII + XII + XVI (1, 40), 4050

Nettastomatid Leptocephali

707

T~\ \ \ x \ \ \ \ \ FIGURE 723. Nettastoma syntresis: USNM 231357, 71 mm SL (from Smith and Castle, 1982: fig. 4). A. Whole view. B. Head. C. Lateral pigment spot. D. Lateral pigment spot of Nettastoma melanura for comparison.

XV (1, 27), 4050 VI + X + XIV (1, 94), 4051 I + IX (1, 40), 4051 II + X (1, 34), 4051 IV (1, 36), 4051 V + XI (1, 41), 4051 IX (ZMUC P311669) (1, 114), 4051 XIII (2, 4149), 4051 XVIII (1, 24), 4056 II + V + XIII (2, 40-42), 4056 VII + XI + XV (1, 37), 4059 I (1, 47), 4067 XI (1, 26), 4067 XII (1, 92), 4069 V (1, 37), 4071 VI (1, 30), 4071 VII (1, 31), 4075 VII (1, 69), 4076 VI + X (1, 82), 4076 VIII + XII + XVI (1, 82), 4077 II + V (2, 87-104), 4077 IV + VII (2, 84-93), 4079 II + V (2, 38-40), 40891 (1, 43), 4089 II + V (10, 34-88), 4089 III + VI (1, 42), 4089 VIII (1, 42), 4089 XIII (1, 38), 4089 XIV (2, 34-42), 4107 I + IX (1, 44), 4107 II + VI + X (7, 39-48), 4107 III + VII + XI (2, 38-42), 4107 IV + VIII + XII (2, 38-39), 4118 II + X + XIV (3, 28-43), 4118 III (2, 31-40), 4118 IV + XII + XVI (11, 35-47), 4118 VII + XI + XV (5,37-44), 4119 XIX (1, 38), 4119 XX (1, 44), 4119 XXI (1, 34), 4119 XXIII (1, 37), 4120 III (1, 80), 41211(1, 37), 4121 II (1, 99), 4123 VI (2, 44-48), 4123 VII (2, 42-47).

Nettastoma syntresis Smith and Bohlke, 1981 Figure 723 Nettastoma melanurum (not of Rafinesque, 1810). Keller, 1976: 142 (part). Nettastoma syntresis. Smith and Castle, 1982: 9, figs. 4-5.

Distinctive Characters. The lateral pigment spot is composed of two discrete melanophores: a horizontally elongate one around the notochord and 'a vertically elongate one immediately above it (Fig. 723C). Nettastoma syntresis has fewer preanal myomeres than N. melanura (53-56 vs 6070). Description. Total myomeres ca 195-201 (n = 5), preanal myomeres 53-56 (5), predorsal myomeres ca 44 (1), lateral pigment spot begins at myomere 71-75 (5). Proportions as % of SL: preanal 43-54 (4), predorsal ca 49 (1), HL 9 (1), greatest depth 23-28 (4). Otherwise identical to Nettastoma melanura except lateral pigment spot composed of two melanophores. Size. The largest specimen examined was 73 mm SL (ANSP 153496). Identification. Smith and Castle (1982:10) identified this leptocephalus on the basis of its general resemblance to Nettastoma melanura, its fewer preanal myomeres, and its geographic distribu-

708

Fishes of the Western North Atlantic, Part 9

tion. The metamorphic specimen examined here (MCZ 62281) has already developed the fourth supraorbital pore, a diagnostic character of Nettastoma syntresis. The identification is thus confirmed.

Spawning and Growth. Specimens were collected between March and September. The smallest specimen (35 mm SL, MCZ 56908) was collected in August. The largest specimen (73 mm SL, ANSP 153496) was collected in April, but a 72-mm specimen was collected in August (USNM 231357) as well. The spawning season thus seems to be extended, but the sample is too small to support many conclusions. Distribution. Five of the seven specimens came from the vicinity of Bermuda, one from the Gulf Stream off North Carolina, and one from the western end of the Northwest Providence Channel in the Bahamas. Study Material. Seven specimens, 37-73 mm SL. BERMUDA: URIZ Ocean Acre A-9-20 (1, 64), 31°39'N, 63°31'W/ 0-110 m, 20 Mar. 1970. 4-29 (1, 37), 32°08'N/ 64°11'W, 0-110 m, 8 Sept. 1968. 12-58 (1, 39), 32°10'N, 63°47'W, 0-150 m, 21 Aug. 1971. USNM 231357 (1, 72), 32°09'N/ 64°11'N/ 0-750 m, 24 Aug. 1971. ANSP 153496 (1, 73), 29°09'N, 66°10'W, 0-85 m, 14 Apr. 1979. GULF STREAM: MCZ 56908 (1, 73), 34°25.5'N/ 70°37'W, 0-1000 m, 5-6 Aug. 1977. BAHAMAS: MCZ 62281 (1, 95; metamorphic), 26°14'N/ 79°22'W, 600 mwo, 19-20 Oct. 1983.

Nettenchelys pygmaea Smith and Bohlke, 1981 Figure 724 Nettastoma type II. Keller, 1976: 146. Nettenchelys pygmaeus. Smith and Castle, 1982: 15, fig. 10.

Distinctive Characters. This leptocephalus resembles those of Nettastoma, but the body is not as deep. In Nettastoma the depth increases abruptly behind the head, and in large specimens the anterior part of the esophagus can be almost vertical. In Nettenchelys, the body deepens more gradually, and the deepest point is around midbody. The leptocephalus of Nettenchelys pygmaea has more total myomeres than that of N. inion/exoria (220-251 vs 209-226) but fewer preanal myomeres (49-56 vs 59-64).

Description. Total myomeres ca 220-251 (n = 27), preanal myomeres 49-56 (78), predorsal myomeres 26-34 (27), prehepatic myomeres 1823 (24), LVBV 49-54 (20), lateral pigment spot begins at myomere 66-79 (75), anal-fin rays ca 267-343 (2). Proportions as % of SL: preanal 3969 (22), predorsal 18-26 (6), HL 6-15 (19), greatest depth 12-22 (22). Body deep anteriorly, tapering sharply toward tail, deepest point near midbody; tail acute. Gut short, about a third to a half SL (greater in very small specimens), with two inconspicuous swellings. Dorsal fin long, beginning at about first fifth to first quarter of SL Head moderate. Pigmentation. An elongate pigment spot around notochord between anus and tip of tail. Melanophores ventrally and laterally on anterior intestinal swelling and laterally on posterior swelling; sometimes one or two melanophores on intestine between anterior and posterior swellings. A band of pigment internally behind eye lateral and posterior to brain; scattered melanophores dorsally on brain; pigment internally on rostrum, on tips of both jaws, and dorsal and posterior to heart. Size. The largest specimen examined was 84 mm SL (UMML Pillsbury 1111). A metamorphic specimen was 82 mm SL (ANSP 148453). Variation. There appears to be a slight difference in the number of myomeres between specimens from the Gulf of Mexico and those from the Caribbean and Atlantic, 220-236 (n = 7) and 227-251 (22), respectively. Identification. Smith and Castle (1982: 15) identified this leptocephalus from a metamorphic specimen. Spawning and Growth. In the Gulf of Mexico, specimens smaller than 20 mm SL were collected in February, April, and July-August, indicating a long spawning season. Beyond this, little can be said. Distribution. Caribbean, Gulf of Mexico, Straits of Florida, Bahamas, Gulf Stream, Bermuda, Sargasso Sea. This is the most common of the deepbodied nettastomatid leptocephali in the western North Atlantic.

Nettastomatid Leptocephali

709

FIGURE 724. Nettenchelys pygmaea: ANSP 155892, 54 mm SL (B, C from Smith, 1979: fig. 12). A. Whole view. B. Head. C. Intestine.

Distribution. Virgin Islands, Bahamas, eastern Gulf of Mexico, Straits of Florida, Gulf Stream, Bermuda. Study Material 92 specimens, 10-84 mm SL. NORTHEAST OF BERMUDA: ZMUC Dana 877-150 (1, 48), 878-100 (3, 60-77), 879-150 (1, 59). SARGASSO SEA: ZMUC Dana 858-25 (1, 64), 876-100 (1, 59), 889 (1, 72), 945-300 (1, 73), 945-400 (1, 81). ZMUC Margrethe 1031 V (11,58), 1043 VI (1, 69), 1054 IV (2, 49-83), 1057 IV (1, 81). ZMUC Dana 1322 X (1, 74), 1337 IX (1, 55). ANSP 153493 (1, 79), 153498 (1, 68), 153503 (1, 41). GULF STREAM: ZMUC Dana 1342 IX (1, 65), 1342 X (1, 50), 1342 XI (2, 35-55), 1345 II (1, 26+), 1345 III (3, 36-68), 1345 V (2,34-61). MCZ 56907 (1,63), 56909 (1, 66), 56927 (1,66), 56928 (1,81). UMML Pillsbury 95 (1,26). STRAITS OF FLORIDA: ZMUC Dana 1228 III (1, 38), 1229 II (2, 51-65), 1230 VII (2, 42-43). UMML Gerda 83 (1, 24), 85 (1, 56), 92 (1, 33), 101 (1, 55), 108 (1, 33), 548 (1, 38), 740 (1, 19), 1309 (1, 65). UMML SL 20 A-2 (1, 35), 59 B-4 (1, 26). YUCATAN CHANNEL: ZMUC Dana 1223 VI (2,2223). ANSP 155408 (1, 14). GULF OF MEXICO: ANSP 148453 (1, 82; metamorphic), 154300 (1, 83), 154301 (2, 66-75), 155403 (1,45), 155404 (1,22), 155405 (1,72), 155406 (1, 24), 155407 (3, 11-26), 155408 (1, 14), 155409 (1, 17), 155410 (1, 67), 155411 (3, 16-20), 155412 (1, 10), 155413 (1, 31), 155414 (1, 41), 155415 (1, 61), 155416 (1, 25), 155417 (1, 52), 155892 (1, 54). MBI214 (1,45). BAHAMAS: ZMUC Dana 1242 IV (1, 15), 1243 III (2, 54-57). UMML

Tursiops 157 (1, 38). UMML Pillsbury 1111 (1, 84), 1174 (1, 49). HISPANIOLA: UMML Carib 7 (1, 37). VIRGIN ISLANDS: ZMUC Dana 1190 II (1, 45), 1190 IX (1, 23), 1196 III (1, 20), 1253 III (1, 26), 1266 IV (1, 61), 1268 III (1, 33). LESSER ANTILLES: ZMUC Dana 1286 IV (1, 22), 1287 IV (1, 22).

Nettenchelys inion Smith and Bohlke, 1981 Nettenchelys exoria Bohlke and Smith, 1981 Figure 725 Nettastoma type I. Keller, 1976: 143. Nettenchelys inion/Nettenchelys exorius. Smith and Castle, 1982: 16.

Distinctive Characters. Like Nettenchelys pygmaea but with fewer total myomeres and more preanal myomeres. Description. Total myomeres 209-226 (n = 35), preanal myomeres 59-64 (53), predorsal myomeres 33-43 (15), lateral pigment spot begins at myomere 76-83 (53), dorsal-fin rays ca 366 (1), anal-fin rays ca 267-314 (12). Otherwise identical to Nettenchelys pygmaea. Size. The largest specimen examined was 122 mm SL, metamorphic (ANSP 148452).

Fishes of the Western North Atlantic, Part 9

710

Distribution. Virgin Islands, Bahamas, eastern Gulf of Mexico, Straits of Florida, Gulf Stream, Bermuda.

130 -

120 -

Study Material. 68 specimens, 13-122 mm SL. BERMUDA/GULF STREAM/SARGASSO SEA: ZMUC Dana 857-50 (2, 48-54), 862-150 (1, 63), 876-100 (6, 5470), 877-50 (1, 71), 877-150 (1, 70), 878-100 (5, 62-79), 879150 (5, 69-83), 880-50 (7, 53-85), 880-100 (2, 55-56), 881100 (2, 66-76), 889 (5, 73-85), 890-200 (1, 76), 891-100 (1, 68), 892-100 (2, 86-95), 892-150 (1, 65), 1342 XII (2, 3845), 1345 III (1, 21), 1345 IV (1, 47), 1353 VII (3, 13-38), 1353 VIII (1, 39), 1353 X (1,35), 1353 XI (5,35-48), USNM 231358 (2, 88-119). MCZ 56910 (1, 74). UMML Pillsbury 1011 (1, 85), 1048 (2, 89-98), 1373 (1, 75). STRAITS OF FLORIDA: UMML Gerda 321 (1, 24). GULF OF MEXICO: UMML Oregon II 7020 1-21-1 (1,18), 7020 2-16-1 (1,25). BAHAMAS: ANSP 148452 (1, 122). VIRGIN ISLANDS: ZMUC Dana 1274 II (1, 19).

11010090 6070605040 30-

Nettenchelys species D

20-

?Nettenchelys sp. D. Smith and Castle, 1982: 18, fig. 12.

10 M

M

FIGURE 725. Nettenchelys inion/exoria, standard length vs month, -I- = metamorphic specimen.

Identification. Smith and Castle (1982:16) identified this leptocephalus from metamorphic specimens. Assuming that Nettenchelys inion and N. exoria are distinct species, it is impossible to determine which of them the present leptocephali represent. Vertebral counts are unavailable for either species. Spawning and Growth. Specimens examined here showed distinct increase in size from spring to late summer (Fig. 725). Spawning thus seems to take place in the spring, and development is completed in about 6-7 months. Keller (1976: 156) found a similar pattern around Bermuda. The one discordant note is the record of two small specimens of 18 and 25 mm SL (UMML Oregon II 7020 1-21-1 and 2-16-1) from the eastern Gulf of Mexico in September. The latter specimens were examined many years ago, and I have been unable to re-examine them to confirm their identity.

Distinctive Characters. Three lateral pigment spots instead of one. Description. Total myomeres ca 220-230 (n = 1), preanal myomeres 63 (1), LVBV 60 (1), lateral pigment spots begin at myomeres 28,52,78. Proportions as % of SL: preanal 52 (1), predorsal ca 33 (1), HL 9 (1), greatest depth 17 (1). Otherwise identical to Nettenchelys pygmaea and N. inion/exoria. Size. The single known specimen is 48 mm SL. Distribution. The specimen was collected in the Mona Passage between Hispaniola and Puerto Rico. Study Material. One specimen, 48 mm SL. HISPANIOLA-PUERTO RICO: UMML Pillsbury 1391, 18°14'N, 69°15'W, 80 m, 10 July 1971.

Hoplunnis tennis Ginsburg, 1951 Figure 726 Facciolella physonema (not of Facciola, 1914). Keller, 1976: 149, fig. 20. Hoplunnis tennis. Smith and Castle, 1982: 20, figs, 15-17, 18a.

Distinctive Characters. The slender, uniformly shallow body and two distinct intestinal swellings characterize all the leptocephali of Hoplunnis

Nettastomatid Leptocephali

711

B

FIGURE 726. Hoplunnis tenuis (B-E from Smith and Castle, 1982: fig. 15): A. ANSP 155913,93 mm SL. B. NMNZ P.ll 185, 76 mm SL; head. C. Same; ventrolateral pigment. D. NMNZ P. 11183, 142 mm SL; head. E. Same; ventral view of developing definitive teeth on roof of mouth.

and Saurenchelys. Several species have melanophores on the lower body wall postanally, but only Hoplunnis tenuis has them above the ventral edge of the myomeres. Description. Total myomeres 232-251 (n = 60), preanal myomeres 44-48 (59), predorsal myomeres 11-18 (24), prehepatic myomeres 13-15 (27), LVBV 46-47 (4). Proportions as % of SL: preanal 23-33 (35), predorsal 9-12 (18), HL 6-8 (22), greatest depth 5-7 (22). Body long and slender, relatively uniform in depth, tail acute. Gut short with two distinct swellings, one anteriorly associated with liver and one near anus below kidney; anus near anterior quarter to third of SL; less than one HL between base of pectoral fin and anterior intestinal swelling. Dorsal fin long, beginning over anterior intestinal swelling. Head moderate. Pigmentation. A series of approximately 8-10 large pigment spots on midlateral line, begin-

ning between head and anterior intestinal swelling and continuing nearly to tip of tail, the first four superficial and stellate, the remainder internal and horizontally elongate. A large stellate melanophore ventrally on gut between head and anterior intestinal swelling; several melanophores ventrally and laterally on anterior intestinal swelling; one or two melanophores on gut between anterior and posterior intestinal swelling; several melanophores on posterior intestinal swelling. A series of superficial stellate melanophores on ventral edge of myomeres postanally. Stellate superficial melanophores on side of head behind and above eye; deep pigment behind brain; pigment internally on rostrum medial to nasal capsule, extending onto tip of upper jaw; melanophores around heart Size. The largest specimen examined was 142 mm SL and was metamorphosing (NMNZ P.11183).

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Fishes of the Western North Atlantic, Part 9

Variation. Specimens from the Gulf of Mexico have 234-246 myomeres (n = 24, x = 240.1), those from the Caribbean have 237-250 (29,243.1), and those from the Guianas and northern Brazil have 232-239 (5, 235.8). The specimen from the Brazilian South Atlantic (MCZ 64491) has 242 myomeres, somewhat more than those from the Guianas. The two specimens from the eastern Atlantic (MCZ 64560 and ZMUC Dana 4010 V) have ca 242 and 251 myomeres, respectively. Identification. Smith and Castle (1982: 21) identified this leptocephalus primarily by the agreement in myomere/vertebral number. Spawning and Growth. In the Gulf of Mexico no clear pattern of spawning time was evident. The smallest specimen, 17 mm SL (ANSP155586), was taken in July, specimens in the 20-29-mm range were collected in February and April, and specimens in the 30-39-mm range were present in all seasons. Spawning thus seems to occur during most of the year. Growth rate and duration of larval life cannot be estimated from the available data. Distribution. Throughout the western Atlantic from southern Brazil through the Caribbean to the Gulf of Mexico, the Straits of Florida, the Bahamas, the Gulf Stream, and Bermuda. There are two records from the eastern Atlantic, off the Canary and Cape Verde Islands. Study Material 265 specimens, 17-142 mm SL. CENTRAL NORTH ATLANTIC: ZMUC Dana 4194 X (1,122), 4201 III (1, incomplete). SARGASSO SEA: ZMUC Dana 877-50 (2, 119-126), 877-100 (1), 887-150 (1, 91), 1335 XI (1, 108), GULF STREAM: ZMUC Dana 1342 IX (1, 84), 1345 III (1), 1345 IV (1, 79), 1345 V (1, 55). MCZ 56929 (2, 50-78), 56930 (1, 73). STRAITS OF FLORIDA: ZMUC Dana 1228 II (1, 75), 1229 II (1,101), 1230 IV (1), 1231 II (1, 40). UMML Gerda 19 (1, 110), 43 (1, 67), 79 (1, 52), 92 (1, 96), 104 (1, 97), 105 (1, 96), 333 (1, 72). UMML Pillsbury 805 (1, 42). UMML SL 35 C-5 (1, 118). UMML Supl. 219 (2, 80-111). UMML unnumbered (3, 44-85). MCZ 56931 (3, 55-87), 59632 (2, 52-70). GULF OF MEXICO: ANSP 154281 (2, 78-91), 154282 (1, 83), 154283 (1,62), 154284(2,69-100), 154285 (1,116), 154286 (3,32-74), 154288 (9, 47-110), 154289 (6,22-100), 154290 (2, 21-95), 155585 (2, 52-55), 155586 (3, 17-70), 155587 (2, 37-69), 155588 (5, 22-90), 155589 (5, 40-62), 155590 (1, 51), 155591 (3, 39-45), 155592 (8, 35-45), 155593 (3, 35-43), 155594 (8, 35-47), 155595 (2, 79-98), 155596 (1,

115), 155597 (4, 33-58), 155598 (2,26-54), 155599 (1,29), 155600 (1, 78), 155601 (1, 32), 155602 (1, 71), 155603 (1, 32), 155604 (10,38-42), 155605 (4,34-42), 155606 (1,39), 155607 (1,115), 155608 (2,50-66), 155609 (1, 31), 155610 (1, 68), 155913 (1, 93). MBI 551 (1, 101), 553 (1, 95), 562 (2, 47-82), 566 (1, 78), 589 (2, 84-117), 590 (1). NMNZ P.11183 (1,142), P.11184 (1,101), P.11185 (1,78). UMML 606-1-T1-A-D (3, 40-115), 606-1-T2-D (2, 77-100), 606-5T2-C + D (1, 100). BAHAMAS: ZMUC Dana 1238 II (1, 50), 1238 IV (2, 31-41), 1238 V (2, 32-41), 1239 VI (1, 111), 1239 VII(1,118), 1243111(1,35). YUCATAN CHANNEL: ZMUC Dana 1223 VI (4,23-35). VIRGIN ISLANDS: ZMUC Dana 1256IV (2, 66-100), 1268 III (3, 25-27), 1269 IV (1, 27), 1269 X (1), 1269 XI (1, 27), 1272 II (4, 24-43), 1272 III (3, 35-39), 1273 III (2, 31-53), 1273 IV (2, 36-40), 1273 VI (1, 125), 1273 IX (4, 35-67), 1274 II (1, 30), 1274 V (1), 1278 III (1, 38), 1278 IV (2, 33-38), 1279 II (1, 46), 1280 II (1, 64), 1280 IV (1, 35), 1281 IV (1, 40), 1289 III (1, 68), 1289 IV (1, 57), 1289 IX (1, 77), 1289 X (1, 65), 1291 IV (1, 49), 1292 IV (1, 24), 1293 III (1, 60), 1293 IV (1, 51), 1294 II (2, 49-50), 1294 m (2, 24-56), 1296 II (3, 70-81), 1296 III (4, 30-62), 1296 IV (1, 20), 1314 III (1, 96), 1314 IV (1, 56). LESSER ANTILLES? ZMUC Dana 1285 III (1, 61), 1287 III (1, 75), 1288 III (1, 45). VENEZUELA: UMML Pillsbury 462 (2). COLOMBIA: UMML Pillsbury 390 (2, 92-101). GUIANAS-BRAZIL: ZMUC Dana 1172 II (9, 28-118), 1172 III (12, 27-64), 1173 I (1, 105), 1174 III (2,101-108), 1177 II (1, 85), 1178 II (1, 75). MCZ 56904 (1, 108), 56922 (1, 75), 56924 (1, 92), 56925 (1, 86), 56926 (3, 48-108). SOUTHERN BRAZIL: MCZ 64491 (1,125). CANARY ISLANDS: ZMUC Dana 4010 V (1, 75). CAPE VERDE ISLANDS: MCZ 64560 (1, 131).

Hoplunnis macrura Ginsburg, 1951 Figure 727 Hoplunnis macrura. Smith and Castle, 1982: 22, figs. 18b, 19.

Distinctive Characters. This leptocephalus also has melanophores on the lower body wall postanally, but they are located below the ventral edge of the myomeres. Description. Total myomeres 221-252 (n = 66), preanal myomeres 51-58 (69), predorsal myomeres 9-13 (43), prehepatic myomeres 19-23 (32), LVBV 54-58 (19). Proportions as % of SL: preanal 28-44 (53), predorsal 9-11 (14), HL 6-7 (15), greatest depth 4-8 (15). Body long and slender, relatively uniform in depth, tail acute. Gut short, with two distinct swellings; anus near first third of SL; about one HL between base of pectoral fin and anterior

Nettastomatid Leptocephali

713

FIGURE 727. Hoplunnis macrura: ANSP 154383, 84 mm SL. A, Whole view. B. Head. C. Tail.

intestinal swelling. Dorsal fin long, beginning between head and anterior intestinal swelling. Head moderate. Pigmentation. A series of approximately 9-10 internal pigment spots around notochord, short to slightly elongate horizontally, beginning midway between head and anterior intestinal swelling and continuing nearly to tip of tail. Specimens from Caribbean and Brazil have a few small melanophores laterally on lower half of body wall postanally. A large, paired, stellate melanophore on esophagus between head and anterior intestinal swelling; melanophores ventrally and laterally on anterior intestinal swelling; a large paired melanophore between anterior and posterior intestinal swelling; melanophores ventrally and laterally on posterior intestinal swelling. A series of stellate melanophores on ventral body wall below myomeres from anus nearly to end of tail. Pigment internally behind brain; internally on rostrum medial to nasal capsule, extending onto tip of upper jaw; melanophores on lower jaw and around heart. Size. The largest specimen examined was 113 mm SL (UMML Pillsbury 191). A slightly smaller specimen, 111 mm SL (ZMUC P311653), was metamorphosing. Variation. Specimens from the Gulf of Mexico have 221-234 myomeres (n = 22, x = 227.6), those

from the Caribbean have 229-244 (34,237.4), and those from the Guianas and Brazil have 243-252 (8, 246.0) (Smith and Castle, 1982: 24). One specimen from the Gulf of Mexico had 205 myomeres (ANSP 148454), and one from the Virgin Islands had 254 (ZMUC P311671), both well outside the range of all the others. Whether these specimens are simply aberrant or represent unrecognized species cannot be determined (Smith and Castle, 1982: 24). Identification. Smith and Castle (1982: 23) identified this leptocephalus primarily by the agreement in myomere/vertebral number. Spawning and Growth. Spawning seems to occur year-round in the Gulf of Mexico. Specimens smaller than 20 mm SL were collected in all seasons. The rate of growth and duration of larval life cannot be determined. Distribution. Distributed widely in the western Atlantic, from Brazil through the Caribbean to the Gulf of Mexico, the Straits of Florida, and the Gulf Stream. It is especially abundant in the western Gulf of Mexico. Study Material. 1096 specimens 10-113 mm SL SARGASSO SEA: ZMUC Dana 1239 X (1, 57). GULF STREAM: UMML 606-8-T3-B (1, 67). MCZ 56911 (1, 95). STRAITS OF FLORIDA: ZMUC Dana 1231 III (1, 67), 1231IV (1, 44). UMML Gerda 107 (1, 38), 200 (1, 46), 340 (1, 53). UMML Pillsbury 809 (1, 92). GULF OF MEXICO:

714

Fishes of the Western North Atlantic, Part 9

FIGURE 728. Hoplunnis diomediana: ANSP 155882, 52 mm SL.

ANSP 154366 (11, 53-88), 154367 (6, 12-80), 154368 (1, 101), 154369 (18,39-67), 154370 (5,82-98), 154371 (1,80), 154372 (1, 84), 154373 (2,64-109), 154374 (1,109), 154375 (51,16-84), 154376 (19,40-94), 154377 (22,30-73), 154378 (30, 16-74), 154379 (1, 101), 154380 (9, 27-93), 154381 (5, 22-90), 154382 (20,10-69), 154383 (16,10-92), 154384 (5, 30-73), 154385 (2, 76-80), 154386 (8, 47-104), 154387 (5, 25-77), 154388 (5, 52-74), 154389 (11, 23-95), 154390 (1, 85), 154391 (10, 21-77), 154392 (161, 10-71), 154393 (39, 11-73), 154394 (17,12-75), 154395 (23,17-97), 154396 (7, 45-95), 154397 (4, 39-83), 154398 (3, 22-90), 154399 (15, 40-99), 155418 (3, 14-23), 155419 (2, 13-17), 155420 (3, 13-20), 155421 (3,11-15), 155422 (1, 91), 155423 (16, 2787), 155424 (3, 54-73), 155425 (1, 94), 155426 (2, 45-64), 155427 (1, 60), 155428 (1), 155429 (10,10-61), 155430 (11, 33-93), 155431 (1, 32), 155432 (2, 65-68), 155486 (1, 77), 155487 (19, 30-47), 155488 (1, 34), 155489 (4, 39-73), 155490 (4, 27-61), 155491 (15, 22-73), 155492 (1, 33), 155493 (1, 43), 155494 (5, 15-34), 155495 (1, 33), 155496 (2, 30-66), 155497 (4, 43-94), 155498 (1, 46), 155499 (3, 53-95), 155500 (1, 81), 155501 (2, 45-52), 155502 (1, 54), 155503 (1, 72), 155504 (1, 33), 155506 (8, 18-53), 155507 (1, 93), 155508 (1, 36), 155509 (7, 38r81), 155510 (1, 53), 155511 (1, 55), 155512 (3, 20-37), 155513 (15, 12-32), 155514 (36, 12-38), 155515 (6, 25-40), 155516 (1, 24), 155517 (1,108), 155518 (1,42), 155519 (15,14-55), 155520 (4, 48-72), 155521 (1, 45), 155522 (10, 20-72), 155523 (4, 18-81), 155524 (3, 40-60), 156073 (73, 19-67), 156074 (8, 19-93), 156075 (66, 29-81), 156076 (32, 27-71). MBI 224 (3,13-84), 241 (7,17-58), 590 (1), 591 (2, 39-55), 604 (1), 774 (11, 44-98). UMML 606-5-T1-B (1, 85). BAHAMAS: ZMUC Dana 1243 V (1, 55). UMML Gerda 1186 (1, 80). UMML Pillsbury 191 (1, 113). YUCATAN CHANNEL: ZMUC Dana 1223 IV (1, 67), 1223 V (2, 69-88), 1223 VI (1, 74). MBI 36 (2, 19-22). HISPANIOLA: UMML Pillsbury 1290 (1, 54), 1390 (4, 60-98), 1391 (1, 74), 1392 (2, 50-55). VIRGIN ISLANDS: ZMUC Dana 1189 VIII (3,4383), 1190 II (1, 80), 1191 II (1, 105), 1192 VI (2, 82-100), 1266 II (1, 65), 1266 IV (1, 99), 1281 V (1, 69), 1289 IV (1, 107), 1291 IV (ZMUC P311671) (1, 97), 1293 IV (2, 76100), 1293 V (2, 83-104), 1293 VI (1, 88), 1296 VI (1, 90), 1310 (1, 102). LESSER ANTILLES: ZMUC Dana 1283 IV (17, 35-60), 1283 V (1, 67). COLOMBIA: ZMUC Dana 3547 I (8, 58-85), 3547 II (12, 34-83), 3547 III (1, 34). PANAMA: ZMUC Dana 1202 V (ZMUC P311653) (2,87-

111). UMML Pillsbury 426 (1, 80). GUIANAS-BRAZIL: ZMUC Dana 1173 II (1, 68), 1174 III (7, 88-105). UMML Pillsbury 677 (1, 64). MCZ 56903 (1, 77), 56914 (2, 6869), 56918 (1, 78), 56925 (6, 58-100), 56926 (3, 65-87).

Hoplunnis diomediana Goode and Bean, 1896 Figure 728 Hoplunnis diomediana. Smith and Castle, 1982: 25, figs. 18d, 20.

Distinctive Characters. This is one of four recognizable species of the Hoplunnis-Saurenchelys group in which the midlateral melanophores are short and vertically elongate. The four species are distinguished from each other by various meristic characters. Description. Total myomeres ca 222-232 (n = 8), preanal myomeres 50-54 (14), predorsal myomeres 13-17 (5), prehepatic myomeres 17-20 (12), LVBV ca 55-56 (4). Proportions as % of SL: preanal 35-50 (6), predorsal 14 (1), HL 8-9 (3), greatest depth 7 (2). Body long and slender, relatively uniform in depth, tail acute. Gut short, with two distinct swellings, anus at about two-fifths SL; about one head length between base of pectoral fin and anterior intestinal swelling. Dorsal fin long, beginning slightly ahead of anterior intestinal swelling. Head moderate to moderately elongate. Pigmentation. A series of approximately 10 short, deep, vertically elongate melanophores around notochord, beginning midway between head and anterior intestinal swelling and continuing nearly to end of tail. A large paired melanophore ventrally between head and anterior intestinal swelling; a few melanophores ventrally and laterally on anterior intestinal swelling; a paired melanophore ventrally between an-

Nettastomatid Leptocephali terior and posterior intestinal swellings; a few melanophores ventrally on posterior intestinal swelling. Pigment internally behind brain; on rostrum medial to nasal capsule, extending onto tip of upper jaw; just behind tip of lower jaw; around heart. Size. The largest specimen examined was 56 mm SL (UMML GE 7202-57), but the maximum size must be substantially larger. No metamorphic specimens were found. Identification. Smith and Castle (1982: 25) identified this leptocephalus as Hoplunnis diomediana because of the close match of myomere/vertebral number and the congruent geographic distribution of leptocephali and adults. Spawning and Growth. Leptocephali of this species were collected in the winter, spring and summer, but there was no obvious difference in size between specimens from different seasons. Hoplunnis diomediana probably resembles its congeners and spawns year-round. Distribution. Eastern and southern Gulf of Mexico, Straits of Florida, and Gulf Stream. Study Material 16 specimens, 18-56 mm SL. GULF STREAM: ZMUC Dana 1345 V (1, 41), 35°07'N/ 72°38'W/150 mwo, 16 May 1922. STRAITS OF FLORIDA: UMML Gerda 79 (1, 54), 25°42'N, 80°05'W, 70-72 m, 20 Dec. 1962. GULF OF MEXICO: ANSP 155012 (1, 24), 23°00.9'N, 91°05.8'W/ 15-20 m/ 18 Feb. 1977. 155013 (1, 38), 20°47.8'N, 92°49.9'W, 45-57 m, 15-16 Apr. 1976. 155014 (1,38), 20P50'N/ 92°58'W/150-153 m, 29 July 1977. 155882 (1, 52), 23°01.6'N/ 90*58.3'W, 22-28 m/ 17 Feb. 1977. NMNZ P.11181 (2, 39-47), 20°48.0'N, 92°48.0'W/ 35-50 m, 16 Apr. 1976. UMML Gerda 471 (1, 40), 24°16'N/ 82°44'W, ca 175 m, 25 Jan. 1965. UMML CI 7209-114 (1), 28°00'N/ 84°34'W. 7303-134 (1, 18), 28°30'N/ 84°51'W. UMML GE 7202-57 (1,56), 26°15'N/ 83°28'W. UMML SUS 7113-80 (1,42), 27°00'N/ 83°48'W. 7120-66 (1,41), 26°30'N/ 84°08'W. 7120-79 (1), 27°00'N/ 83°31'W. UMML 8B 7201819 (1, 49), 27°15'N/ 83°54'W. Hoplunnis similis Smith, 1989 Hoplunnis sp. A. Smith and Castle, 1982: 26, fig. 20.

Distinctive Characters. Identical to Hoplunnis diomediana but with many more myomeres (250260 vs 222-232). Description. Total myomeres ca 250-260 (n = 24), preanal myomeres 56-61 (25), predorsal

715

60 70 60 50 40 30 20 10 -

D

J

F

M

A

M

J

JA

FIGURE 729. Hoplunnis similis, standard length vs month.

myomeres 13-17 (4), prehepatic myomeres 2023 (23). Proportions as % of SL: preanal 33-50 (7), predorsal 12 (4), HL 8-9 (4), greatest depth 6-8 (4). Otherwise identical to Hoplunnis diomediana. Size. The largest specimen examined was 74 mm SL (ZMUC Dana 1293 II). Identification. The species to which this leptocephalus belongs must be closely related to Hoplunnis diomediana, have 250-260 vertebrae, and be found in the Caribbean and the Bahamas. Hoplunnis similis meets all these requirements perfectly. Spawning and Growth. The distribution of SL against season (Fig. 729) suggests an increase in size from winter to spring, with specimens larger than 50 mm being present only in March and April. A December-January spawning season would thus be indicated, with metamorphosis in late spring or summer. The sampling effort was heavily weighted toward the March-April period, however, and the resulting size distribution may be an artifact. Metamorphic specimens were not found, and specimens in the 30-50 mm size range were present during the entire period. Distribution. Specimens are known from the Lesser Antilles, the southwestern and northwestern Caribbean, the northern Bahamas, and the Gulf Stream off North Carolina.

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Fishes of the Western North Atlantic, Part 9

FIGURE 730. Saurenchelys cognita: ANSP 155905, 49 mm SL. Study Material. 26 specimens, 23-74 mm SL. GULF STREAM: ZMUC Dana 1352 II (1, 33). BAHAMAS: UMML Tursiops 174 (3, 33-49). YUCATAN CHANNEL: ZMUC Dana 1223 VII (1, 32). SOUTHWESTERN CARIBBEAN: ZMUC Dana 1238 IV (2, 2339). VIRGIN ISLANDS: ZMUC Dana 1188IV (1,33), 1266 IV (1, 33), 1268 III (2, 30-38), 1269 X (1, 31), 1272 III (1, 35), 1274 V (1, 40), 1278 II (1, 53), 1278 IV (1, 44), 1280 IV (1, 38), 1281 IV (1, 49), 1289 IV (2, 56-66), 1293 II (2, 64-74), 1293 III (1, 60), 1293 IV (1, 62). LESSER ANTILLES: ZMUC Dana 1286 V (1, 35), 1287 V (1, 58). Hoplunnis species B Hoplunnis sp. B. Smith and Castle, 1982: 26, fig. 20.

Distinctive Characters. Identical to Hoplunnis diomediana but with more preanal and prehepatic myomeres. Description. Total myomeres ca 220-235 (n = 6), preanal myomeres 55-58 (6), predorsal myomeres 14 (1), prehepatic myomeres 22-25 (6). Otherwise identical to Hoplunnis diomediana. Size. The largest specimen examined was 53 mm SL (ZMUC Dana 1192 VI). Identification. Although it has the same number of total myomeres as Hoplunnis diomediana, this leptocephalus has significantly more preanal and prehepatic myomeres. It also occurs well outside the known range of H. diomediana. There is no known adult with which this leptocephalus can be matched. Distribution. The known specimens all came from the Virgin Islands. Study Material Six specimens, 29-53 mm SL. VIRGIN ISLANDS: ZMUC Dana 1192 VI (2, 47-53), 17°43.4'N, 64°54.3'W, 300 mwo, 15 Dec. 1921. 1266IV (1, 51), 17°45'N, 64°55.5'W, 300 mwo, 13 Mar. 1922. 1276 V (1, 29), 17°43'N, 64°56'W, 100 mwo, 28 Mar. 1922. 1278 IV (1, 45), 17°43'N, 64°56'W, 29 Mar. 1922. 1280 IV (1, 34), 17°43'N, 64°56'W, 300 mwo, 31 Mar. 1922.

Hoplunnis species C Hoplunnis sp. C. Smith and Castle, 1982: 27, fig. 20.

Distinctive Characters. Identical to Hoplunnis diomediana but with only ca 210 myomeres. Description. Total myomeres ca 210 (n = 1), preanal myomeres 52 (1), prehepatic myomeres 18 (1). Otherwise identical to Hoplunnis diomediana. Size. The only known specimen is 29 mm SL. Identification. This specimen has the same number of preanal and prehepatic myomeres as Hoplunnis diomediana but significantly fewer total myomeres. In addition, it was collected far outside the known range of H. diomediana. Distribution. The specimen was collected in the southwestern Caribbean north of Panama. Study Material One specimen, 29 mm SL. SOUTHWESTERN CARIBBEAN: ZMUC P311654, 11°00'N, 77°40'W, 300 mwo, Dana 3547, 24 Aug. 1928.

Saurenchelys cognita Smith, 1989 Figure 730 Saurenchelys sp. A. Smith and Castle, 1982: 27, figs. 18e, 21.

Distinctive Characters. This leptocephalus is characterized by its small, round kidney and its unusually low myomere count. Description. Total myomeres ca 201-209 (n = 9), preanal myomeres 59-64 (19), predorsal myomeres 17-19 (7), prehepatic myomeres 23-25 (19), LVBV 61-62 (7). Proportions as % of SL: preanal 39-67 (18), predorsal 14-17 (3), HL 5-10 (5), greatest depth 7-18 (7). Body long and slender, relatively uniform in depth, tail acute. Gut relatively short, with two distinct though small swellings; anus near mid-

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717

FIGURE 731. Saurenchelys species B: ZMUC P311656, 84 mm SL (from Smith and Castle, 1982: fig. 18f).

length; distance between base of pectoral fin and anterior intestinal swelling approximately twice HL; kidney small, round, atop posterior intestinal swelling. Dorsal fin long, beginning before anterior intestinal swelling. Head moderate. Pigmentation. A series of approximately eight short to rounded melanophores internally around notochord centered on myosepta, beginning between head and anterior intestinal swelling and extending nearly to tip of tail. Small melanophores laterally on anterior intestinal swelling, ventrally and laterally on posterior intestinal swelling, ventrally and laterally on kidney. Pigment internally behind brain, on palate, and on tip of upper jaw. Size. The largest specimen examined was 73 mm SL (NMNZ P.I 1187). A slightly smaller specimen, 69 mm (ZMUC P311672), was beginning metamorphosis. Identification. This is almost certainly the leptocephalus of the adult described elsewhere in this volume (p. 593) as Saurenchelys cognita. They are both found mainly in the Gulf of Mexico, and they have the same unusually low myomere/vertebral count. The metamorphic specimen (ZMUC P311672) shows the enlarged median vomerine teeth characteristic of both Hoplunnis and Saurenchelys, but its pectoral fin is markedly reduced, indicating that the adult is without a pectoral fin. Saurenchelys lacks the pectoral fin as an adult, whereas Hoplunnis has it. This plus the close agreement in geographic distribution and myomere/vertebral count support the identification. Spawning and Growth. In the Gulf of Mexico specimens were collected from January to November. The size range of specimens in January and February was 9-73 mm SL, in July and August 13-68 mm SL. Saurenchelys cognita thus has

an extended spawning period, probably yearround. Distribution. Known from the Gulf of Mexico, the Northeast Providence Channel, Bahamas, and the Gulf Stream off Virginia and Maryland. It appears to be most common in the eastern Gulf of Mexico. Study Material. 34 specimens, 9-77 mm SL. GULF STREAM: MCZ 62283 (1, 77), 62284 (2, 31-45), 62291 (1, 52), 62292 (2, 37-55), 62293 (2), BAHAMAS: ZMUC Dana P311672 (1, 69). GULF OF MEXICO: ANSP 155390 (1, 38), 155391 (1, 4ti), 155392 (1, 18), 155393 (1, 42), 155905 (2, 27-49). NMNZ P, 11187 (1, 73). UMML B 7132-97 (1,12). UMML CI7303-60 (1,66), 7303-82 (1,15), 7303-96 (2,9-56), 7303-98 (1, 27), 7303-114 (1, 56), 731196 (2,13-26), 7313-98 (1, 68), 7320-50 (1, 51). UMML GE 7101-14 (1, 21), 7117 81-1 (1, 30), 7117 81-3 (2, 26-27), 7202-25A (1,10). UMML SUS 7120-107 (1, 62), 7121-163 (1, 59).

Saurenchelys species B Figure 731 Saurenchelys sp. B. Smith and Castle, 1982: 28, figs. 18f, 21.

Distinctive Characters. This leptocephalus has more myomeres than any other western Atlantic member of the Hoplunnis-Saurenchelys group except Hoplunnis tenuis and H. similis. It is distinguished from the former by lacking melanophores along the ventral edge of the myomeres postanally. It differs from the latter in having round rather than vertically elongate midlateral melanophores and in having a slightly greater distance between the head and the anterior intestinal swelling. The two specimens of Saurenchelys sp. B have a strongly convex dorsal profile of the head. Description. Total myomeres 249 (n = 1), preanal myomeres 58 (1), predorsal myomeres 17

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FIGURE 732. Saurenchelys species C (from Smith and Castle, 1982: fig. 18g,h): ZMUC P311657, 70 mm SL (upper) and ZMUC P311658, 30 mm SL (lower).

(1), prehepatic myomeres 22 (1). Proportions as % of SL: preanal 34 (1), HL 6 (1), greatest depth 4(1). Body long and slender, relatively uniform in depth, tail acute. Gut short, with two distinct swellings, anus near first third of SL; slightly more than one head length between base of pectoral fin and anterior intestinal swelling. Dorsal fin long, beginning before anterior intestinal swelling. Head moderate, strongly convex in dorsal profile. Pigmentation. Available specimens faded, but pattern seems to be as follows. A series of round spots around notochord, but number and extent uncertain. A paired stellate melanophore ventrally between head and anterior intestinal swelling; melanophores on anterior intestinal swelling; a paired melanophore ventrally between anterior and posterior intestinal swelling; melanophores laterally on posterior intestinal swelling. Pigment internally behind brain, internally on rostrum, and on tip of upper jaw. Size. The larger of the two specimens is 84 mm SL (ZMUC P311656). Identification. This leptocephalus cannot be identified with a known adult. It is referred to Saurenchelys primarily for convenience and because its intestinal swellings are somewhat smaller than those of the known Hoplunnis leptocephali. Distribution. The two specimens were collected in the Northwest Providence Channel, Bahamas. Study Material. Two specimens, 67-84 mm SL.

BAHAMAS: ZMUC P311656 (1, 84), 26°13/N, 78°14'W, 800 mwo, Dana 1238 I, 11 Feb. 1922. ZMUC Dana 1238 II (1, 67), same, 600 mwo.

Saurenchelys species C Figure 732 Saurenchelys cancrivora. Blache, 1977: 176, figs. 60-61. Saurenchelys sp. C. Smith and Castle, 1982: 28, figs. 18g, 21.

Distinctive Characters. The lateral pigment consists of three large, rounded spots, all postanal. Small specimens may have one or two much smaller spots before the level of the anus, but the basic pattern of three large postanal spots is unique to this leptocephalus. Description (western Atlantic specimens only). Total myomeres ca 223-225 (n = 2), preanal myomeres 70-73 (4), predorsal myomeres 17-19 (3), prehepatic myomeres 28-31 (3). Proportions as % of SL: preanal 43-57 (5), predorsal 14 (1), HL 7-8 (2), greatest depth 7-8 (2). Body long and slender, relatively uniform in depth, tail acute. Gut short, with two distinct swellings, anus near midbody; about 1.5 HL between base of pectoral fin and anterior intestinal swelling. Dorsal fin long, beginning between head and anterior intestinal swelling. Head moderate. Pigmentation. Three large, round, stellate melanophores around notochord postanally; small specimens sometimes with one or two much smaller midlateral melanophores over or before

Nettastomatid Leptocephali

719

FIGURE 733. Saurenchelys stylura: ZMUC P311665, 96 mm SL (from Smith and Castle, 1982: fig. 23b).

anus. Melanophores laterally on anterior intestinal swelling, ventrally and laterally on posterior intestinal swelling. Pigment internally behind eye around sides and back of brain and on palate. Size. The largest specimen examined was 70 mm SL (ZMUC P311657). Variation. Specimens from the Gulf of Guinea differ from those in the western Atlantic in several meristic characters: total myomeres 192-210, preanal myomeres approximately 50, predorsal myomeres 12-15, prehepatic myomeres 20-25 (Blache, 1977: 176). Identification. Blache (1977) identified this leptocephalus as Saurenchelys cancrivora Peters but gave little convincing evidence. It is treated here as Saurenchelys for convenience, but its identification as a species of Hoplunnis cannot be ruled out. Metamorphic specimens are not available. Spawning and Growth. The specimens were collected in March and April and ranged in size from 16-70 mm SL. In fact the largest and smallest specimens were taken in the same tow. The spawning season is evidently prolonged. Distribution. Known from the Virgin Islands and the Gulf of Guinea. Study Material Six specimens, 16-70 mm SL. VIRGIN ISLANDS: ZMUC P311657 (2,16-70), 17°43'N, 64°56'W, 300 mwo, 17 Apr. 1922. P311658 (2, 32-43), 17°43'N, 64°56'W, 300 mwo, 31 Mar. 1922. ZMUC Dana 1266 IV (1, 57), 17°45'N, 64°55.5'W/ 300 mwo, 13 Mar. 1922. 1296 III (1,37), 17°43'N, 64°56'W/ 300 mwo, 19 Apr. 1922.

Saurenchelys stylura (Lea, 1913) Figure 733 Leptocephalus stylurus Lea, 1913: 36, figs. 28-31, pi. 5, no. 3 (original description, 26°03'N/ 15°00'W, six syntypes

ZMUB). Castle, 1969b: 65. Blache, 1977: 180, figs. 62a, 63. Saurenchelys stylurus. Smith and Castle, 1982: 29, figs. 16, 23b, 24a,c, 25.

Distinctive Characters. Midlateral pigment spots horizontally elongate; no melanophores on ventral body wall postanally. Description (myomere counts for western Atlantic specimens only, proportions for eastern and western Atlantic specimens). Total myomeres 209-227 (n = 20), preanal myomeres 5256 (25), predorsal myomeres 14-18 (26), prehepatic myomeres 18-22 (36). Proportions as % of SL: preanal 30-60 (39), predorsal 9-12 (11), HL 4-7 (13), greatest depth 5-8 (13). Body long and slender, relatively uniform in depth, tail acute. Gut short, with two distinct swellings, anus near anterior third of SL; more than one HL between base of pectoral fin and anterior intestinal swelling. Dorsal fin long, beginning slightly ahead of anterior intestinal swelling. Head moderate. Pigmentation. A series of pigment spots internally around notochord, beginning between head and anterior intestinal swelling and extending nearly to end of tail, the anteriormost spot rounded, the rest horizontally elongate. Melanophores laterally on anterior intestinal swelling; a few melanophores opposite kidney-intestine interface. A pigment spot internally immediately below brain, sometimes extending over part of lateral surface; pigment on palate. Size. Maximum size approximately 130 mm SL (Smith and Castle, 1982: 29). Variation. Populations from different geographic areas show distinct though overlapping ranges of myomere counts (Smith and Castle, 1982: 29, table 3).

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FIGURE 734. Facciolella species B: ZMUC P311649, 75 mm SL (from Smith and Castle, 1982: fig. 32b).

Identification. The most advanced of the specimens examined are approaching metamorphosis and already show a marked reduction in the pectoral fin. The metamorphic specimen illustrated by Blache (1977:182, fig. 63d) has lost the pectoral fin completely, and Lea (1913: 37) described two of his syntypes as lacking the pectoral fin. This indicates that the leptocephalus belongs to Saurenchelys rather than to Hoplunnis. Spawning and Growth. In the western Atlantic, specimens were collected in March, April, September, and November. A 15-mm specimen was collected in April (ZMUC Dana 1284 IV), and two 21-mm specimens were taken in November (ZMUC Dana 1172 III and 1173 III). Like most of the Hoplunnis-Saurenchelys group, this species seems to have an extended spawning season. Distribution. Widely distributed on both sides of the tropical Atlantic and through the IndoWest Pacific from Africa to Hawaii. In the western Atlantic it is known only from the coast of Brazil to the Lesser Antilles; it has not been collected west of about 62°W. Etymology. Apparently from the Latin stilus or stylus (a pointed instrument) and the Greek oura (tail). The name is emended here to agree in gender with the feminine Saurenchelys. The fact that Lea changed the ending to -urus indicates that he was using it as an adjective. Study Material (Atlantic only). 92 specimens, 15-109 mm SL. LESSER ANTILLES: ZMUC Dana 1283 IV (5, 42-52), 1284 III (1, 37), 1284 IV (3, 15-46), 1285 IV (1, 46), 1286 V (1, 45), 1287 V (2, 44-51), 3545 III (1, 54). GUIANAS: ZMUC Dana 1178 IV (2, 42-44). MCZ 56904 (2, 69-72), 56905 (1, 90), 56906 (1, 57+), 56924 (1, 101), 56925 (4, 45-79). BRAZIL: ZMUC Dana 1172 III (1, 71), 1173 III (1, 90). MCZ 56912 (3, 60-83), 56913 (2, 58-62), 56914 (16, 49-93), 56915 (9,56-91), 56916 (1,94), 56917 (1,66), 56918 (2,73-100), 56919 (2,67-98), 56920 (1,95), 56921 (1, 61), 56923 (1, 66). WEST AFRICA: ZMUC Dana 4001 V (2,

105-109), 4003 XI (2, 98-103), 4005 XI (1,106), 4008 V (2, 67-76), 4009 IV (3, 39-93), 4009 V (5, 54-96), 4010 IV (1, 48), 4010 V (9, 32-62).

Facciolella species B Figure 734 Facciolella sp. B. Smith and Castle, 1982: 38, figs. 31, 32b.

Distinctive Characters. Leptocephali of Facciolella are long and slender and uniform in depth, much like Hoplunnis and Saurenchelys, but the gut lacks the two distinct swellings. Instead, the gut is thrown into a series of irregular undulations or thickenings. In addition, the head is more elongate at all stages, and the rostral cartilage is produced anteriorly and overhangs the lower jaw. Of the two species known in the western Atlantic, sp. B has fewer total myomeres but more preanal myomeres than sp. C. It has a more complete series of midlateral melanophores than sp. C, but it lacks the small melanophores on the lower half of the body wall postanally. Description. Total myomeres ca 240-254 (n = 3), preanal myomeres 57-61 (10), predorsal myomeres 15-16 (4). Proportions as % of SL: preanal 35-56 (8), predorsal 15-17 (2), HL 10-14 (8), greatest depth 5-10 (6). Body long and slender, relatively uniform in depth, tail acute. Gut relatively short, with irregular undulations or thickenings, anus at about anterior third of SL in larger specimens. Dorsal fin long, beginning shortly behind head. Head long, rostral cartilage produced anteriorly, upper jaw overhangs lower. Pigmentation. A series of short, vertically elongate melanophores around notochord, beginning shortly behind head and continuing to end of tail. A series of large melanophores on gut. A band of pigment internally lateral and posterior to brain; pigment internally on rostrum to tip of

Nettastomatid Leptocephali

721

FIGURE 735. Facciolella species C: A. MBI 200, 87 mm SL. B. Same; head. C. ANSP 155020, 37 mm SL; head.

upper jaw; pigment on tip of lower jaw; pigment internally dorsal and posterior to heart. Size. The largest specimen examined was 86 mm SL (MCZ 62296); it was not near metamorphosis. Identification. Leptocephali of the Mediterranean species Facciolella oxyrhynchus were identified by Grassi (1913: 162) from metamorphic specimens. Leptocephali elsewhere cannot be identified to species because the adults cannot adequately be distinguished (see p. 596). Spawning and Growth. Specimens were collected in March, April, and November. The smallest specimen (18 mm SL, ZMUC Dana 1198 II) was collected in April, the largest (ZMUC P311649) in March, both near the Virgin Islands. An extended spawning period is indicated. Distribution. Facciolella sp. B leptocephali are known from the Gulf Stream off Virginia, the Virgin Islands, and the equatorial Atlantic off the coast of Brazil. Study Material. Ten specimens, 18-86 mm SL. GULF STREAM: MCZ 62295 (1, 48), 37°05.3'N, 70°58.8'W, 0-1010 m, 21 Aug. 1982. 62296 (1, 86), 36°54.3'N, 73°54.7'W, 0-383 m, 14 Aug. 1982. VIRGIN ISLANDS: ZMUC Dana 1196II (1, 29), 17°43'N, 64°56'W, 600 mwo, 4 Jan. 1922.1198 III (2,18-20), 17°43'N, 64°56' W, 500 mwo, 4 Jan. 1922.1266 II (1,47), 17°45'N, 64°55.5'W, 800 mwo, 13 Mar. 1922. 1273 VIII (ZMUC P311649) (1,

75), 17°43'N, 64°56'W, 700 mwo, 24 Mar. 1922. 1294 III (1, 28), 17°43'N, 64°56'W, 600 mwo, 18 Apr. 1922. 1296 III (1, 32), 17°43'N, 64°56'W, 300 mwo, 19 Apr. 1922. BRAZIL: ZMUC Dana 1171 IV (1, 43), 8°19'N, 44°35'W, 300 mwo, 13 Nov. 1921.

Facciolella species C Figure 735 (?)Nettastomatidae Type III. Keller, 1976: 151. Facciolella sp. C. Smith and Castle, 1982: 38, figs. 31, 32c.

Distinctive Characters. This leptocephalus has more total myomeres but fewer preanal myomeres than Facciolella sp. B. It has sparser midlateral pigment than sp. B, but it has small melanophores scattered over the lower half of the body wall postanally. Description. Total myomeres ca 253-264 (n = 8), preanal myomeres 43-47 (14), predorsal myomeres 18-20 (9). Proportions as % of SL: preanal 22-47 (13), predorsal 12-18 (7), HL 7-15 (12), greatest depth 4-9 (12). Body long and slender, relatively uniform in depth, tail acute. Gut short, anus near anterior fifth of SL in larger specimens. Dorsal fin long, beginning shortly behind head. Head long, rostral cartilage produced anteriorly, upper jaw overhangs lower. Pigmentation. A few midlateral melanophores,

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Fishes of the Western North Atlantic, Part 9

mainly anteriorly, but not forming a complete series from head to tail. Small melanophores scattered over lower half of body wall postanally, becoming fewer toward tail. A series of large melanophores along gut. A band of pigment internally behind eye lateral to brain; a few spots dorsolateral to brain; a spot internally behind brain; pigment internally on rostrum medial to nasal capsule; pigment on tip of upper jaw and just behind tip of lower jaw; pigment internally anterior and posterior to heart. Size. The largest specimen examined was 109 mm SL (ANSP 156728). The larger specimens showed signs of approaching metamorphosis, but none were actually undergoing it. Spawning and Growth. In the Gulf of Mexico, specimens were collected only in April, but the size range was 16-87 mm SL, indicating a long spawning season. Elsewhere specimens were collected in February, March, April, July, and December. Two 15-mm specimens were taken in December and April; specimens larger than 80 mm SL were recorded in April, July, and November. There is no evidence of a discrete spawning season anywhere in the western Atlantic. Distribution. Widely distributed in the western Atlantic from Brazil and the Lesser Antilles to the Gulf of Mexico, the Straits of Florida, the Bahamas, the Gulf Stream, and the Sargasso Sea. Remarks. Keller (1976:151) described five spec-

imens of larval Facciolella from Bermuda. They had 42-46 preanal myomeres and a scattering of melanophores on the lower body wall postanally, both characters typical of Facciolella sp. C. The total myomere count, however, was 245-248, well below that of sp. C The identification of these leptocephali is thus uncertain. Leptocephali of three other species of Facciolella are known from the eastern North Atlantic, F. oxyrhynchus (Bellotti, 1883), F. sp. A of Smith and Castle (1982), and F. halimyon (van Utrecht, 1983). None of these has been collected west of 40°W. Study Material. 17 specimens, 15-109 mm SL. SARGASSO SEA: ZMUC Dana 889-100 (1.88), 28°20'N, 63°50'W/100 mwo, 21 July 1920. 939-400 (1,91), 26°10'N, 56°30'W, 400 mwo, 17-18 Apr. 1921. 945-400 (1, 84), 25°00'N, 64°10'W, 400 mwo, 24 Apr. 1921. ANSP 153492 (1, ca 90), 24°42'N, 60P30'W, 0-150 m, 23 Mar. 1979. GULF STREAM: ZMUC Dana 892-150 (1,81), 30°49'N, 73°30'W, 150 mwo, 25 July 1920. 1345 III (1,47), 35°07'N, 72°38'W, 300 mwo, 16 May 1922. BAHAMAS: ANSP 156728 (1, 109),25°59'N, 75°32.7'W, 0-500 m, 3 Mar. 1981. STRAITS OF FLORIDA: ZMUC Dana 1225 III (1, 39), 25°58'N, 82°22'W, 300 mwo, 2 Feb. 1922. YUCATAN CHANNEL: NMNZ P.11186 (1, 87), 21°09.6'N, 86°13.5'W, 1500 mwo, 24 July 1977. GULF OF MEXICO: ANSP 155020 (1, 37), 20°47.3'N, 92°53.4'W, 45-75 m, 15 Apr. 1976. 155021 (1, 34), 19°26.8'N, 95°25.7'W, 45-50 m, 17 Apr. 1976.155022 (1, 15), 19°26.4'N, 95°24.7'W, 20-40 m, 17 Apr. 1976. MBI 200 (1,87), 20°00.0'N, 94°34.3'W, 2000 mwo, 16 Apr. 1976. LESSER ANTILLES: ZMUC Dana 1287 III (1,15), 16°04'N, 61°52'W, 300 mwo, 8 Apr. 1922. BRAZIL: ZMUC Dana 1174II (1,81), 05°35'N, 51°08'W, 600 mwo, 16 Nov. 1921.

Family Congridae: Leptocephali DAVID G. SMITH

Characters. Moderate to large leptocephali, maximum size about 90-300 mm. Body moderate to elongate, tail variable. Gut usually simple, preanal length three-quarters SL or greater. Dorsal fin variable, from very long to very short. Ventral pigment variable but always present; lateral pigment variable, sometimes absent. Head and snout moderately short to moderately elongate. Composition. Congrid leptocephali vary widely in most of the important characters and consequently are difficult to characterize on the family level. Several fairly well defined subgroups are present, which seem to reflect the taxonomic structure of the family. One of the most distinctive groups of leptocephali comprises the genera Ariosoma and Parabathymyrus (and by inference Bathymyrus as well), the most derived members of the subfamily Bathymyrinae. These are large, elongate leptocephali with a long, simple gut and a very short dorsal fin. The lateral pigment consists of minute melanophores outlining a short section of the myosepta immediately below the midlateral line. Ventral melanophores are also very small; they are subcutaneous and lie along the bottom of the gut anteriorly, switching to the top of the gut behind the gastric region. Large, expanded melanophores are found only in young individuals of certain species. In some species the intestine trails freely behind the body for a distance that can exceed the body length. Another large group includes the genera Conger, Gnathophis, Rhechias, Uroconger, and Rhynchoconger. These leptocephali are smaller and not quite as elongate as the previous group. The dorsal fin originates near midlength. The ventral

melanophores are larger and superficial. The lateral pigment, when present, consists of a midlateral series of individual melanophores; some species have an additional row of melanophores above and below the midlateral row. Typically, a crescentic patch of pigment is present beneath the eye, although this is reduced or absent in some species of Rhynchoconger. Paraconger belongs to the Bathymyrinae, but its leptocephalus resembles that of the Conger group more than the Ariosoma group. It is only moderately elongate, and the ventral and lateral pigment consist of relatively large and superficial melanophores. The dorsal fin is short, however, as in Ariosoma, and there is no subocular pigment. Paraconger is the most primitive member of the Bathymyrinae. The fact that its leptocephalus resembles that of the Conger group suggests that the Conger-type is the primitive congrid leptocephalus. Leptocephali of the Heterocongrinae also resemble those of the Conger group, particularly in the form of the lateral and ventral pigment. The gut is notably shorter, however, and the dorsal fin is longer. There is no subocular pigment. The leptocephali of Acromycter and Pseudophichthys are markedly different from any of the preceding. Acromycter is elongate with a series of ophichthid-like loops in the gut. Pseudophichthys is shorter, but it also has loops in the gut, though less pronounced than those of Acromycter. Pseudophichthys has a distinctive pattern of pigmentation, with melanophores scattered over the lateral body wall. Leptocephali of Xenomystax are large with several expanded melanophores along the midlat723

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Fishes of the Western North Atlantic, Part 9

eral line, distributed randomly on either side of the body. Only a few ventral melanophores are present.

A few leptocephali are known that seem to be congrids but cannot be identified with a known genus or species.

KEY TO THE CONGRID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC

la. Lateral pigment in form of oblique lines on myosepta just below midlateral line; dorsal fin begins over anus 2 Ib. Lateral pigment, when present, not in the form of oblique lines; dorsal fin begins distinctly before anus 7 2a. Fewer than 140 myomeres Ariosoma balearicum, p. 726 3 2b. More than 140 myomeres 3a. Gut not trailing freely behind body Ariosoma sp., p. 729 3b. Gut trails freely a variable distance behind body 4 4a. Free section of gut short, ca 3-17% SL; 169-174 myomeres (except off Brazil, where counts are ca 158-162) Ariosoma selenops, p. 730 4b. Free section of gut, when intact, at least 40% SL; fewer than 160 myomeres 5 5a. One series of oblique lines on myosepta, below midlateral line; LVBV at myomere 68-76 . . Parabathymyrus oregoni, p. 733 5b. Three series of oblique lines on myosepta: one above dorsal flexure, one below midlateral line, and one above ventral flexure 6 6a. Last vertical blood vessel (LVBV) at myomere 90-103; total myomeres 147-155; body depth 11-17% SL Ariosoma anale, p. 731 6b. LVBV at myomere 87-88; total myomeres ca 158; body depth 8-9% SL Ariosoma coquettei, p. 733 7a. Gut with ten prominent loops, each capped by a pigment spot Acromycter spp., p. 758 7b. Gut simple or with only low, inconspicuous loops not capped by a pigment spot 8 9 8a. Lateral pigment scattered over side of body 8b. Lateral pigment, when present, largely confined to midlateral region 10 9a. Some lateral pigment spots consist of clusters of smaller melanophores; myomeres 131-137 Pseudophichthys splendens, p. 757 9b. Lateral pigment composed exclusively of small, single melanophores; myomeres 114-116 . . .CONGRIDAE Gen. B sp. A, p. 761 lOa. Lateral melanophores subcutaneous 11 lOb. Lateral melanophores, when present, superficial 12 lla. Lateral melanophores in a staggered row; suborbital pigment absent; 153-170 myomeres . . . Rhynchoconger flavus, p. 747 lib. Lateral melanophores in a more even row; suborbital pigment sometimes present; 172-182 myomeres Rhynchoconger gracilior/guppyi, p. 749 12a. Lateral pigment consists of a few very large, expanded melanophores distributed unequally on the two sides of the body 13 12b. Lateral melanophores, when present, moderate or small 15 13a. Body depth uniform, does not increase abruptly behind head CONGRIDAE Gen. C, p. 762 13b. Body depth increases abruptly behind head, then tapers gradually toward tail 14

Congrid Leptocephali 14a. 14b. 15a. 15b. 16a.

725

Ca 189-221 myomeres Xenomystax congroides, p. 759 Ca 175 myomeres Xenomystax bidentatus, p. 761 Dorsal fin begins near anterior quarter of SL; preanal length about % to % SL 16 Dorsal fin begins near or behind midlength; preanal length usually exceeds 80-90% SL . . . 19 Lateral pigment a row of small, rounded melanophores, not exactly on myosepta, never more 17 than one per myomere 16b. Lateral pigment a row of small melanophores exactly on myosepta, sometimes more than one per myoseptum 18 17a. Myomeres 159-167 Heteroconger halis, p. 737 17b. Myomeres 137-148 Heteroconger luteolus, p. 738 18a. Myomeres 168-176; Brazil and Gulf of Guinea Leptocephalus inferomaculatus, p. 739 18b. Myomeres ca 130; Caribbean CONGRIDAE Gen. A sp. A, p. 741 19a. No suborbital pigment; posterior teeth compressed and blade-like (Fig. 742D); predorsal length Paraconger spp., p. 735 more than % SL 19b. A crescentic patch of pigment immediately below eye; posterior teeth conical; predorsal length 20 about % to % SL 20a. Lateral pigment absent 21 20b. Lateral pigment present 24 21 a. Snout rather elongate, acute Gnathophis spp. (part), p. 745 21b. Snout relatively short 22 Conger esculentus, p. 744 22a. Myomeres 133-135 22b. Myomeres 140 or more 23 23a. Myomeres 140-148 Conger oceanicus, p. 742 23b. Myomeres 150-158 Conger triporiceps, p. 743 24a. A single row of lateral melanophores 25 24b. Three rows of lateral melanophores 33 25a. Only a few inconspicuous lateral melanophores on posterior part of body 26 25b. A complete series of midlateral melanophores extending full length of body 27 26a. Snout relatively short Conger oceanicus (part), p. 742 26b. Snout relatively long Gnathophis spp. (part), p. 745 27a. Fewer than 150 myomeres 28 27b. More than 150 myomeres 31 28a. Preanal myomeres 113-124; larger than ca 80 mm SL Conger oceanicus (part), p. 742 28b. Preanal myomeres 96-107; any size 29 29a. Fewer than 140 myomeres Rhechias dubia (part), p. 752 29b. More than 140 myomeres 30 30a. Tail less acute; Gulf of Mexico and U.S. Atlantic coast Rhechias dubia (part), p. 752 30b. Tail more acute; Caribbean Rhechias thysanochila, p. 753 31a. More than 200 myomeres Uroconger syringinus, p. 751 31b. Fewer than 200 myomeres 32 32a. LVBV at myomere 51-57 Rhechias sp. A, p. 754 32b. LVBV at myomere 60-64 Rhechias sp. B, p. 754 33a. Myomeres 158-168 Rhechias sp. C, p. 755 33b. Myomeres 176-187 Bathyuroconger vicinus, p. 756

726

Fishes of the Western North Atlantic, Part 9

FIGURE 736. Ariosoma balearicum (C-E from Smith, 1979: fig. 36): A. ANSP 155901,11 mm SL, Gulf of Mexico. B. ANSP 155922, 94 mm SL, Gulf of Mexico. C. Same; head. D. Same; body near gastric region. E. Same; tail.

Ariosoma balearicum (Delaroche, 1809) Figures 736-738 Helmichthys diaphanus Costa, 1846: 2, pi. 31. Leptocephalus taenia Kaup, 1856b: 148, pi. 17, fig. 9, part. Leptocephalus marginatus Kaup, 1856b: 152, pi. 19, fig. 19, part. Leptocephalus affinis Facciola, 1883a: 4, pi. 4, fig. 1. Leptocephalus inornatus Facciola, 1883a: 5, pi. 4, fig. 2. Ariosoma balearicum. Facciola, 1893: 125. Leptocephalus eckmani Stromman, 1896:16, pi. 1, figs. 1-3. Leptocephalus scheelei Stromman, 1896: 21, pi. 1, figs. 67, part. Leptocephalus rex Eigenmann and Kennedy, 1902:86, fig. 3. Leptocephalus spinocadux Lea, 1913: 22, pi. 3, no. 4. Leptocephalus microphthalmus Beebe and Tee Van, 1928: 58, fig. Leptocephale 3. Blache, 1963: 10, pi. 3.

Distinctive Characters. Leptocephali of the Ariosoma group are distinguished by their elongate body, long gut, and very short dorsal fin, which begins over the anus. The short, diagonal lines outlining the myomeres immediately below the myosepta are found elsewhere only among cer-

tain ophichthid leptocephali, but the latter have a much shorter gut. Ariosoma balearicum has fewer myomeres (121-136) than any other western Atlantic representative of the group (148-174). It further differs from Ariosoma selenops, A. anale, A. coquettei, and Parabathymyrus oregoni in having a shorter snout and lacking the free posterior section of the gut. Description. Total myomeres 121-136 (n = 666), preanal myomeres ca 90-126 (270), LVBV 62-72 (281). Proportions as % of SL: preanal 87-98 (169), HL 3-12 (214), greatest depth 8-17 (114). Body elongate, deepest point slightly behind midlength. Gut long and narrow, without loops or swellings. Dorsal and anal fins confined to posterior extremity of body, confluent with caudal fin. Head and snout relatively short, tip of snout acute. Pigmentation. A series of short diagonal lines on myosepta immediately below midlateral line from head to tail, each line composed of a row of minute melanophores. A series of small me-

Congrid Leptocephali lanophores along bottom of esophagus, switching to top of intestine behind stomach-gall bladder complex and continuing to anus. A series of small melanophores on dorsal midline for most of length. Small specimens have a series of larger, more widely spaced melanophores on dorsal and ventral midlines, but these disappear with growth. Size. These leptocephali grow to about 200 mm SL before metamorphosing. This is more than half the TL of the largest known adults, giving Ariosoma balearicwn one of the largest larva-toadult size ratios of any eel. Variation. The specimens examined for this study show the bimodal distribution of myomere counts typical of this species in the Atlantic, with modes of 126 and 132 (Fig. 737). It was shown elsewhere (see family Congridae, p. 498, Table 46), however, that three populations of Ariosoma balearicum exist in the western North Atlantic: a northern high-count form, a southern high-count form, and a geographically intermediate lowcount form. Why are the two high-count forms not distinguishable among the leptocephali? The discrepancy seems to be more apparent than real. If the two high-count populations in Table 46 (family Congridae, p. 498) are combined, and if the anomalously low southern specimen (123 vertebrae, RMNH 27397) is eliminated, the composite population forms a smooth if slightly skewed curve with a mean value of 130.6 vertebrae (n = 47). If the low-count localities are similarly combined (these seem to represent a single population), the mean is 124.6 vertebrae (n = 49). Jespersen (1942: 10) found that leptocephali have on the average one more myomere than adults have vertebrae. If the numbers of vertebrae given above are increased by one, the resulting sample means become 125.6 and 131.6, almost exactly the number of myomeres shown in Figure 737. Identification. Leptocephali of Ariosoma balearicum were identified through metamorphosing specimens in the Mediterranean (Facciola, 1893; Grassi, 1913; D'Ancona, 1931; Sparta, 1938). Spawning and Growth. Collections from the western Gulf of Mexico are most instructive for

727 Ariosoma balearicum = Western Atlentic ee e whole = Yucatan Chennel = Gulf of Mexico

10-

130

Totel

r

136

Myomeree

FIGURE 737. Distribution of total myomeres in leptocephali of Ariosoma balearicum from three sources: western North Atlantic as a whole, Yucatan Channel, and western Gulf of Mexico.

study of growth rates because spawning there seems to be limited to one season. In the area between about 20°-28°N and 94°-97°W, the mean SL for 481 specimens collected in November was 56 mm. For 120 specimens collected in February it was 124 mm, and for 48 specimens collected in April it was 126 mm. Although there was little change in average size between February and April, the minimum SL increased markedly from 65 mm to 103 mm. In February only three of 120 specimens (2.5%) were metamorphosing, but in April fully 71% (34 of 48) had reached that stage. This accounts for the lack of significant increase in average size between February and April, because metamorphosis is a time of negative growth. In July-August, leptocephali were practically absent; only eight specimens were collected. Spawning in the western Gulf thus occurs sometime between August and November. Between November and February the leptocephali grow an average of 70 mm. By April they have reached full size and are metamorphosing. Ariosoma balearicum thus seems to require 7-8 months to complete its larval development.

Fishes of the Western North Atlantic, Part 9

728

SL

tocephali found off South America can be presumed to belong to the southern population. Leptocephali from the southern area can, however, be transported north and west through the Caribbean. High-count leptocephali were present in samples from the Yucatan Channel, but they were all larger than 130 mm SL (Fig. 738). From the Yucatan Channel it is an easy journey through the Straits of Florida and into the Gulf Stream. Thus southern high-count leptocephali may be found within the range of the northern population, but they would all be very large. Any high-count leptocephali in this area smaller than about 130 mm would almost certainly belong to the northern form. in

FIGURE 738. Total myomeres vs SL in leptocephali of Ariosoma balearicum from the Yucatan Channel.

During preliminary sorting aboard the Anton Dohrn in the Sargasso Sea in March-April, 1979, 810 leptocephali of Ariosoma balearicum were found, the great majority of which had high myomere counts. A subsample of 125 specimens had 126-136 myomeres (x = 131.5). The size distribution formed a normal curve with a mode of 85-89 mm SL; 349 of 396 specimens measured were between 80 and 99 mm SL. If the rate of growth here is similar to that of specimens from the Gulf of Mexico, these leptocephali would be about 3 months old. Spawning would then have taken place in December. Distribution. Throughout the North Atlantic, including the Mediterranean, and south into the Gulf of Guinea. The larva of this species is perhaps the most common leptocephalus in the western North Atlantic. In the Gulf of Mexico, only low-count leptocephali are found. In the Caribbean, the Gulf Stream, and the Sargasso Sea both high-count and low-count forms occur (Fig. 737). The northern and southern high-count forms are indistinguishable from each other morphologically because of the broad overlap in myomere number, but most of them can probably be separated by geographical criteria. The currents are such that leptocephali spawned north of the Antilles will probably not be carried to the south. Any lep-

Study Material. 3131 specimens, 4-205 mm SL. CENTRAL ATLANTIC: UMML 402-7-T4-C (1, 153). SARGASSO SEA: ISH Anton Dohrn 5527 IK-1 (5,65-90), 5534 MOC 2-7 (1), 5538 IK-2 (1,83), 5550 MT-3 (9, 88195), 5556 MOC 5-7 (1, 76), 5562 IK-3 (3, 86-97), 5576 IK-5 (33, 74-105), 5588 IK-6 (16, 77-101), 5588 MOC 6-0 (1, 91), 5596 IK-7 (37, 80-105), 5596 MT-8 (21, 83-105), 5603 IK-8 (141, 79-110), 5610 IK-9 (3, 86-92), 5615 IK-10 (10, 79-176), 5623 IK-12 (75, 79-93), 5628 IK-13 (7, 7595), 5632 IK-14 (11, 83-102), 5632 MT-11 (24, 81-159), 5638 IK-15 (1, 88), 5641 MT-12 (1, 95), 5643 IK-16 (11, 83-93), 5653 IK-17 (55, 82-94), 5661 IK-18 (1), 5666 IK19 (52,76-87), 5666 MT-13 (4,83-93), 5674IK-21 (59,8295), 5679 IK-22 (5, 79-88), 5684 IK-23 (52, 80-96), 5684 MOC 13-8 (1, 84), 5688 IK-24 (1, 80-1-), 5689 IK-25 (21, 83-94), 5695 IK-26 (2,103-104), 5698 IK-27 (16, 80-128), 5703 IK-28 (1, 90), 5709 IK-29 (39, 81-169), 5715 IK-30 (4,82-92), 5717 IK-31 (7,77-103), 5725 IK-33 (5,15-154), 5731 IK-34 (1, 84), 5738 IK-35 (1, 45), 5738 IK-36 (2, 9394), 5738 MT-19 (1, 88), 5746 IK-39 (1,15), 5750 IK-40 (3, 89-103), 5756 IK-41 (1, 127), 5760 MT-21 (4, 147-158). UMML Pillsbury 1371 (1, 85), 1375 (1, 78), 1378 (20, 80101), 1379 (13, 75-113). GULF STREAM: UMML Pillsbury 100 (6, 12-59), 106 (3, 23-125), 107 (1, 109), 115 (3, 26-30), 116 (5, 23-29), 123 (1, 62). UMML Oregon 5126 (1,141). UMML 606-8-T1-C + D (1,82), 606-8-T2 (1,173), 606-8-T3-C -I- D (1, 67), 606-9-T1-C + D (1, 65). BAHAMAS to BERMUDA: UMML Pillsbury 145 (1, 84), 155 A (1, 100), 157 (2, 65-98), 160 (1, 88), 163 (6, 46-125), 164 (89, 25-111), 165 (33, 31-90), 186 (1, 44), 1017 (2, 92-95), 1019 (1,106), 1032 (12,27-104), 1034 (2, 39-47), 1036 (39, 30-109), 1049 (10, 41-131), 1050 (3, 58-62), 1051 (5, 4760), 1067 (1, 83), 1081 (1, 90), 1086 (1, 56), 1089 (1, 55), 1094-1095 (1,105). UMML Gilliss 2-D (1, 59), 2-E (3, 6887). UMML Sands 3-A (4, 84-93), 8-A (2, 90-96), 11 (2, 71-104), 13-B (1, 101). BAHAMAS: ANSP: 154806 (22, 36-68), 154807 (9, 24-69), 154808 (16, 45-87), 154809 (1, 131), 154810 (2, 61-107), 156003 (1, 27), 156004 (1, 47),

Congrid Leptocephali 156032 (8, 25-171). UMML Gerda 488 (1, 50), 497 (1, 34), 535 (3, 122-141), 547 (18, 84-142), 548 (15, 65-142), 549 (1, 52), 685 (2, 30-32), 686 (1, 77), 738 (2, 66-135), 1057 (1, 20). UMML Pillsbury 180 (3, 45-85), 181 (15, 42-90), 183 (2, 41-43), 184 (9, 42-95), 190 (6, 34-61), 191 (9, 3483), 191 (1, 30), 192 (2, 48-102), 193 (3, 65-81), 195 (4, 35-90), 196 (2, 28-64), 206 (1, 23), 216 (1, 44), 217 (4, 36139), 1005 (1, 42), 1105 (33, 11-27), 1106 (1, 21), 1107 (1, 14), 1109 (2, 12-13), 1110 (1, 26), 1114 (24, 11-31), 1115 (9, 26-108), 1116 (16, 12-117), 1117 (6, 55-108), 1118 (5, 17-54), 1119 (2, 27-30), 1120 (1, 100), 1121 (5, 15-103), 1122 (1, 31), 1124 (1, 28), 1128 (1, 67), 1129 (1, 13), 1139 (2, 72-137). UMML Tursiops 153 (3, 42-129), 157 (1, 47), 167 (1, 30), 174 (1, 95), 176 (1, 100). UMML Supl. 12 (3, 90-101), 164 (1, 133), 201 (1, 134). UMML ONR TOTO 2-6 (1, 140), 3-3 (1, 18), 3-4 (1, 105), 5-6 (1, 117), 7-4 (1, 102), 8-2 (5, 64-112). UMML TOTO T-2 (1, 61), T-5 (7, 75-95), T-7 (12, 60-119), T-8 (1, 89), T-10 (7, 82-111). STRAITS OF FLORIDA: UMML Gerda 10 (1,120), 46 (1, 127), 71 (4, 113-133), 79 (1, 79), 83 (1, 29), 84 (4, 52-63), 85 (9, 51-68), 86 (8, 47-72), 89 (1, 123), 98 (6, 108-143), 99 (4,112-139), 100 (1,116), 101 (1,123), 195 (1, 28), 263 (1, 118), 279 (1, 115), 284 (3, 112-155), 327 (1, 133), 343 (1, 54), 348 (1,139), 351 (7, 30-150), 352 (2,133-162), 463 (2,73-103), 473 (4,75-134), 1220 (1,48). UMML Pillsbury 95 (3,110-117), 809 (1,184). UMML Tursiops 136 (2,1255), 152 (10, 31-74), 340 (2, 75-120). UMML Silver Bay 4372 (1, 73), 4373 (1, 71). UMML SL 8 C-4 (1, 107), 8 D-5 (1, 115), 10 C-l (1, 46), 13 B-l (2, 107-136), 13 B-4 (1, 119), 13 C-4 (1, 89), 14 C-0 (1, 130), 21 A-l (1, 53), 22 C-2 (1, 38), 22 C-3 (2, 30-58), 22 C-5 (1, 34), 22 C-6 (1, 51), 24 A-6 (3, 61-100), 33 B-5 (1, 92), 34 B-8 (1, 58), 45 A-7 (1,80). UMML Supl. 180 (1, 64), 192 (4,110-120). UMML NG 16-14 (1, 86). GULF OF MEXICO: ANSP 154567 (2, 95-110), 154778 (12, 48-70), 154781 (2, 11-154), 154782 (1, 75), 154784 (5, 55-63), 154785 (2,141-145), 154786 (7, 49-69), 154787 (2, 103-108), 154788 (13, 47-123), 154789 (2, 135-155), 154790 (1, 150), 154791 (1, 113), 154795 (1, 88), 154796 (3, 24-76), 154797 (3, 109-149), 154798 (2, 158-164), 154800 (5,119-147), 154801 (3,114-142), 154805 (1,145), 155076 (8, 40-58), 155079 (1), 155080 (74, 4-57), 155081 (1,67), 155083 (2,43-54), 155084 (26,4-13), 155086 (1, 57), 155089 (4, 11-13), 155092 (1, 70), 155093 (1, 42), 155095 (8,5-10), 155097 (4,12-32), 155098 (1), 155100 (1, 16), 155901 (74, 4-57), 155922 (3, 93-101), 155952 (18, 874), 155953 (7,130-159), 155954 (1,116), 155956 (13, 59160), 155958 (1,125), 155959 (5,113-163), 155960 (3,123166), 155961 (3,112-155), 155963 (1,160), 155966 (28,69158), 155967 (2, 133-164), 155968 (2, 116-122), 155969 (47,10-80), 155970 (25,20-94), 155971 (35,19-100), 155972 (89,10-71), 155976 (3,143-152), 155977 (4,7-169), 155980 (29,7-143), 155982 (43,37-69), 155983 (54,40-107), 155984 (7,103-115), 155985 (29,39-86), 155986 (7,49-113), 155988 (2, 111-113), 155989 (14, 88-160), 155991 (1, 105), 155992 (21, 42-73), 155993 (44, 23-100), 155995 (8, 107-149), 155996 (29, 46-73), 155997 (7, 105-139), 155998 (7, 13-

729

122), 155999 (2, 140), 156001 (1, 77), 156002 (3, 31-69), 156005 (6,144-155), 156006 (27,73-159), 156007 (23,101156), 156008 (30, 93-167), 156009 (18, 76-150), 156010 (16, 92-160), 156011 (46, 74-165), 156012 (65, 69-161), 156013 (55, 83-165), 156014 (18, 92-157), 156016 (3, 97142), 156017 (9, 61-149), 156018 (7, 82-143), 156020 (3, 116-152), 156021 (22,89-162), 156022 (18,95-160), 156023 (7, 105-134), 156024 (8, 65-124), 156025 (2, 147-157), 156026 (7, 87-146), 156027 (13, 104-155), 156028 (7, 6157), 156029 (4, 135-166), 156030 (49, 84-166), 156031 (52, 83-166), 157603 (1, 31), 157605 (1, 131). MBI 61 + 63 (2, 29-35), 223 (1), 561 (3, 116-125), 582 (1), 583 (1). UMML 606-3-T1-B (1, 94). UMML Oregon II 1-14-1 (1, 162). UMML station 1-haul 4-sample 2 (1, 160), station 1-haul 19-sample 1 (1, 132), station 1-haul 19-sample 2 (1,53). YUCATAN CHANNEL: ANSP 154773 (5, 31-78), 154774 (1, 100), 154775 (1, 99), 154776 (1, 155), 154777 (4, 32-85), 154779 (1, 169), 154780 (3, 145-169), 154783 (1, 120), 154793 (2, 175-195), 154794 (1, 160), 154799 (1, 167), 154802 (1,170), 154803 (3,114-145), 154804 (2,172184), 155075 (1,36), 155078 (1,54), 155082 (1,66), 155085 (2, 44-56), 155087 (1, 151), 155088 (1, 140), 155090 (1, 172), 155091 (2, 50-54), 155094 (1,49), 155096 (2, 60-63), 155099 (1,48), 155955 (10,42-175), 155957 (1,186), 155962 (1, 176), 155964 (11, 30-155), 155965 (5, 39-185), 155973 (4,40-165), 155975 (8,33-122), 155978 (8,48-163), 155981 (1, 190), 155979 (1, 120), 155987 (2, 162-186), 155990 (1, 158), 155994 (2, 54-186), 156000 (1, 172), 156015 (6, 35200). MBI 175 (1, 54). UMML Pillsbury 602 (1,167), 603 (2, 169-178). JAMAICA: UMML Oregon 5408 (3, 100124). HISPANIOLA: UMML Pillsbury 1152 (5, 65-116), 1176 (5, 85-100), 1288 (1,146), 1289 (1, 96), 1388 (1, 76), 1389 (6, 83-122), 1392 (18, 56-123). UMML Silver Bay 5143 (1, 92), 5154 (1, 94), 5162 (1, 95), 5180 (2, 88-92), 5181 (1, 113), 5185 (2, 95-98). UMML Oregon 5425 (3, 85-126). PUERTO RICO: UMML Pillsbury 823 (1, 139), 824 (2, 78-80), 825 (7, 72-80), 827 (3, 73-86), 828 (1, 61). VIRGIN ISLANDS: UMML Pillsbury 1398 (1,103). LESSER ANTILLES: UMML Pillsbury 473 (1,140), 474 (4,105112), 475 (18,101-154), 476 (1,115). UMML Oregon 4985 (20, 82-102), 5011 (2, 91-107), 5014 (1, 98). UMML Geronimo 6-89 (8, 94-144). VENEZUELA: UMML Pillsbury 462 (2,106-124), 463 (1, 80). UMML Geronimo 7-112 (3, 114-122). COLOMBIA: UMML Pillsbury 390 (1,103), 454 (1, 135), 457 (1, 137). PANAMA: UMML Pillsbury 426 (1,164), 1318 (1,187), 1320 (1,205). NICARAGUA: UMML Pillsbury 1345 (2, 143-176), 1346 (1, 169), 1347 (1, 165). GUIANAS: UMML Pillsbury 677 (1, 42), 680 (1, 142). BRAZIL: UMML Laserre 1-11 (1, 158), 1-28 (1, 67).

Ariosoma species Distinctive Characters. This leptocephalus is identical to Ariosoma balearicum except for its more numerous myomeres (148-149 vs 121-136).

Fishes of the Western North Atlantic, Part 9

FIGURE 739. Ariosoma selenops: ANSP 158287, 76 mm SL, Yucatan Channel. A. Whole view. B. Head. C. Tail.

Description. Total myomeres 148-149 (n = 4), preanal myomeres 133 (1), predorsal myomeres 141 (1), LVBV 76-79 (4). Proportions as % of SL: preanal 94-95 (2), HL 5-9 (3), greatest depth 913 (4). Otherwise identical to Ariosoma balearicum. Size. The largest specimen examined was 230 mm SL (ANSP 153491). Identification. The only species of Ariosoma known in the western North Atlantic whose vertebral count matches the myomere count of this leptocephalus is A. anale, and that species is identified with another leptocephalus below. The present leptocephalus is so similar to that of A. balearicum that one would expect the adults to be closely similar as well. Within the genus, however, A. balearicum and A anale lie at opposite ends of the spectrum in many characters. It seems more likely that the present leptocephalus represents an undescribed species, closely related to Ariosoma balearicum but with significantly more vertebrae. Distribution. Sargasso Sea; Yucatan Channel; Straits of Florida; Tongue of the Ocean, Bahamas; Gulf Stream off Georgia. Study Material Five specimens, 20-76 mm SL. SARGASSO SEA: ANSP 153491 (1, 230), 22°21'N, 61°42'W, 130 m, 22 Mar. 1979. GULF STREAM: UMML Pillsbury 115 (1, 48), 31°49'N, 77°51'W, 10 m, 28 July

1964. BAHAMAS: UMML Pillsbury 1116 (1,20), 25°16'N, 77°56'W, 115 mwo, 29 Aug. 1969. STRAITS OF FLORIDA: UMML Gerda 100 (1, 75), 25°18'N, 79°50'W, 25 m, 9/10 May 1963. YUCATAN CHANNEL: ANSP 155077 (1,49), 21°34.0'N, 85°56.4'W, 13 m, 15 Feb. 1977.

Ariosoma selenops Reid, 1934 Figure 739 Ariosoma selenops. Smith, 1971: 45; 1979: 26. Keller, 1976: 172.

Distinctive Characters. Ariosoma selenops has more myomeres than any other species of Ariosoma or Parabathymyrus in the western Atlantic (169-174 vs 121-157). The free section of the gut is much shorter than that of Ariosoma anale, A. coquettei, and Parabathymyrus oregoni. Description (preanal distance measured to point where gut becomes free of body). Total myomeres 169-174 (n = 24), preanal myomeres 160169 (20), LVBV 96-103 (20). Proportions as % of SL: preanal 96-98 (5), HL 4-10 (14), greatest depth 9-14 (15), free length of intestine 3-17 (6). Otherwise similar to Ariosoma balearicum, but the snout is somewhat more elongate, and the intestine trails freely a short distance behind the body. In the few specimens that appeared to be intact, the free section of the intestine was about 3-17% SL

Congrid Leptocephali

731

10

B

FIGURE 740. Ariosoma anale: ANSP 155921, 101 mm SL, Gulf of Mexico (B from Smith, 1979: fig. 38). A. Whole view. B. Midbody.

Pigmentation. As in Ariosoma balearicum, but the row of small melanophores along bottom of gut extends all the way to anus. Size. The largest specimen examined here was 344 mm SL (MCZ 64795); Keller (1976: 172) recorded five specimens of 349-402 mm. As adults do not appear to exceed 500 mm TL, this species has an extraordinarily large leptocephalus. Identification. Ariosoma selenops is the only bathymyrine species known in the western North Atlantic whose vertebral count fits the myomere count of the present leptocephali (168-174 north of Brazil). Distribution. Yucatan Channel, Straits of Florida, Bahamas, Gulf Stream, Sargasso Sea, and central Atlantic. Study Material. 29 specimens, 24-344 mm SL. SARGASSO SEA: ANSP 153495 (1, 283). GULF STREAM: UMML Pillsbury 106 (1, 72), 107 (2, 45-47). BERMUDA: UMML Pillsbury 1032 (1,106), 1042 (1,134). BAHAMAS: ANSP 154177 (1, 58). UMML Pillsbury 1116 (1, 60), 1118 (1, 57). UMML Tursiops 107 (2, 24-49), 136 (1, 51), 179 (6, 37-58). YUCATAN CHANNEL: ANSP 154236 (1, 65), 155250 (1, 49), 155251 (1, 44), 155252 (3,

28-52), 155899 (1, 29), 158287 (1,76). LESSER ANTILLES: UMML Oregon II 7239-10 (2, 41-56). EAST-CENTRAL ATLANTIC MCZ 64795 (1, 344).

Ariosoma anale (Poey, 1860) Figure 740 Leptocephale 6. Blache, 1963: 12, pis. 15, 16. Cynoponticus ferox (not of Costa, 1846). Blache, 1968a: 702, part (38-mm specimen). Bathymyrus sp. Castle, 1970a: 9. Parabathymyrus sp. Blache, 1977: 108. Leptocephalus scalaris (not of Castle, 1964). Smith, 1979: 27.

Distinctive Characters. This leptocephalus and that of Ariosoma coquettei differ from all the other western Atlantic species of Ariosoma and Parabathymyrus in having three series of short, diagonal lines outlining the myosepta. Some specimens of A. anale also have an oval patch of small melanophores midlaterally. Like Ariosoma coquettei and Parabathymyrus oregoni, Ariosoma anale has a long free section of the gut posteriorly, but it has distinctly more LVBV myomeres (90-

732

Fishes of the Western North Atlantic, Part 9

103 vs 87-88 and 68-76, respectively) and slightly fewer total myomeres (147-155 vs 158 and 153157). It is also deeper-bodied (11-17% SL) than the other two (7-9% SL). Description (preanal distance measured to point where gut becomes free of body). Total myomeres 147-155 (n = 19), preanal myomeres 131140 (13), predorsal myomeres 131-141 (7), LVBV 90-103 (25). Proportions as % of SL: preanal 9495 (9), HL 4-7 (9), greatest depth 11-17 (11). Snout rather elongate, as in Ariosoma selenops. Intestine trails freely behind body for a distance that can exceed body length. Otherwise similar to Ariosoma balearicum but body somewhat deeper. Pigmentation. As in Ariosoma balearicum, with these differences. The row of small melanophores along bottom of gut extends all the way to anus. Three series of short, diagonal lines on myosepta: one just above dorsal flexure, one just below midlateral line, and one just above ventral flexure. Sometimes a small round or oval patch of small melanophores midlaterally around 50th myomere. Size. The largest specimen examined was 187 mm, and it was beginning metamorphosis (UMML Pillsbury 384). Blache (1977: 110) recorded a metamorphic leptocephalus of 175-179 mm TL, but he also had premetamorphic leptocephali as large as 260 mm. Castle (1970a: 9) reported leptocephali up to 255 mm TL. Variation. The free portion of the intestine seems to develop with age, and very small specimens may not show it. It is also subject to damage. Identification. This species and the two that follow have a long section of the gut trailing free posteriorly. Their overall morphology indicates that they belong to the Ariosoma group of bathymyrine congrids. There are three such species in the western North Atlantic with vertebral counts that match the myomere counts of these leptocephali: Ariosoma anale (146-150), A. coquettei (155160), and Parabathymyrus oregoni (149-155). It was pointed out elsewhere (p. 494) that Ariosoma anale and A. coquettei share several advanced character

states with Parabathymyrus, so their leptocephali might be expected to show similarities as well. If this line of reasoning is accepted, it remains to determine which adult goes with which leptocephalus. The most useful character here is the position of the last vertical blood vessel (LVBV), which is related to the number of precaudal vertebrae in the adult. The three species, leptocephali and adults, differ markedly in this character. The present leptocephalus has significantly more LVBV myomeres (90-103) than do the other leptocephali (87-88 and 68-76). Ariosoma anale has significantly more precaudal vertebrae (83-90) than do Ariosoma coquettei (ca 75) and Parabathymyrus oregoni (67-70). By this criterion, therefore, the present leptocephalus fits Ariosoma anale. The total myomere/vertebral counts of the three species overlap somewhat, but the ranges and the means differ. The present leptocephalus has slightly fewer myomeres (147-155) than the other two leptocephali (158 and 153-157), and Ariosoma anale has slightly fewer vertebrae (146-150) than Ariosoma coquettei (155-160) and Parabathymyrus oregoni (149-155). This character reinforces the conclusion that the present leptocephalus belongs to Ariosoma anale. Spawning and Growth. In the western Gulf of Mexico, leptocephali of this species were collected in all seasons, but predominantly in the summer (13 of 22 specimens). Specimens smaller than 20 mm SL were collected in April and JulyAugust. Of these, the three specimens collected in April were 15,17, and 24 mm SL; the 17 specimens collected in July-August ranged from 13 to 120 mm SL; one specimen was collected in November (44 mm), and one in February (69 mm). It thus appears that spawning is spread over nearly half the year, at least from April to August. The largest specimen, 120 mm SL, was collected in August, giving it a probable age of 4 or 5 months. This specimen was probably not close to its maximum size, however. The limited material available does not permit the length of larval life to be estimated, although it is probably at least as long as that of Ariosoma balearicum. Remarks. Castle (1964b: 16) described a similar

Congrid Leptocephali leptocephalus from the western Pacific as Leptocephalus scalaris, and Mochioka et al. (1982) recorded additional specimens, possibly of more than one species. Distribution. Southern Gulf of Mexico, Yucatan Channel, Florida Straits, Sargasso Sea, southern Caribbean, Guianas, Gulf of Guinea, central Equatorial Atlantic. Study Material 38 specimens, 13-187 mm SL. SARGASSO SEA: ISH Anton Dohrn 5632 MT-11 (1, 139). BAHAMAS: UMML Pillsbury 190 (1,177). STRAITS OF FLORIDA: UMML Gerda 195 (1, 94). UMML SL 13 C-3 (1, 63), 37 C-6 (1, 137). UMML Supl. 180 (1, 156). GULF OF MEXICO: ANSP 154230 (1, 98), 155272 (1, 24), 155273 (1, 17), 155274 (1, 18), 155275 (1, 14), 155276 (2, 15-19), 155277 (1, 21), 155278 (1,44), 155279 (1,69), 155280 (2, 55-58), 155281 (1, 22), 155283 (2, 49-55), 155284 (1, 47), 155285 (1, 15), 155288 (1, 13), 155921 (3, 58-120), 157611 (2,68-71). YUCATAN CHANNEL: ANSP 155282 (1, 19), 155286 (1,22), 155287 (1,24). LESSER ANTILLES: UMML Pillsbury 467 (1, 148), 470 (1, 139), 475 (1, 85). COLOMBIA: UMML Pillsbury 384 (1, 187). GUYANA: MCZ 64754 (2, 42-97).

Ariosoma coquettei Smith and Kanazawa, 1977 Distinctive Characters. Like Ariosoma anale, this leptocephalus has three series of diagonal lines outlining the myosepta. It differs from A. anale by having fewer LVBV myomeres (87-88 vs 90103), more total myomeres (ca 158 vs 147-155), and a shallower body (8-9% SL vs 11-17). Description. Total myomeres 158 (n = 4), preanal myomeres 149-150 (4), LVBV 87-88 (3). Proportions as % of SL: greatest depth 8-9 (4), free length of intestine 40 (1). Body shallower than that of Ariosoma anale. Snout rather elongate, as in Ariosoma selenops. Intestine trails freely behind body for a distance slightly less than half the SL. Pigmentation. As in Ariosoma anale. Size. The largest specimen examined was 220 mm SL (MCZ 64751). It was not near metamorphosis. Identification. This leptocephalus has fewer LVBV myomeres (87-88) than the preceding one (90-103) and more than the following one (68-

733

76). In this it agrees with Ariosoma coquettei, which has fewer precaudal vertebrae (ca 75) than A. anale (83-90) and more than Parabathymyrus oregoni (ca 67-70). The present leptocephalus has more total myomeres (158) than either of the other two (147-155 and 153-157, respectively). Ariosoma coquettei also has more total vertebrae (155-160) than Ariosoma anale (146-150) and Parabathymyrus oregoni (149-155). Adults of Ariosoma coquettei occur only off the Guianas, and the present leptocephalus is restricted to the same area. Spawning and Growth. The size range of the four specimens, 43-220 mm SL, indicates an extended spawning season. No estimate can be made of the rate of growth or the length of larval life. Remarks. The length of the free portion of the intestine seems to be substantially less than that of Ariosoma anale and Parabathymyrus oregoni but more than that of Ariosoma selenops. In the one specimen that appeared to be intact, it measured 40% of the SL. In A. anale and P. oregoni, it often exceeds the SL, whereas in A. selenops it is less than 20% of the SL. Distribution. The specimens were collected off Guyana and Suriname. Study Material. 4 specimens, 43-220 mm SL, GUYANA: MCZ 64750 (1,189), 09°01'N, 59°04'W, 5100 m, 27 Sept. 1973. 64752 (1,107), 08°59'N, 57°34'W, 4750 m, 27 Sept. 1973. 64753 (1, 43), 08°58'N, 57°40'W, 5050 m, 27 Sept. 1973. SURINAME: MCZ 64751 (1, 220), 09°06'N, 55°09'W, 495-0 m, 26 Sept. 1973.

Parabathymyrus oregoni Smith and Kanazawa, 1977 Figure 741 Parabathymyrus oregoni. Keller, 1976: 172 (probably). Leptocephalus macrenteron (not of D'Ancona, 1928). Smith, 1979: 27.

Distinctive Characters. This leptocephalus resembles those of Ariosoma anale and A. coquettei, but it has only one series of diagonal lines outlining the myosepta. It is intermediate in total myomeres (153-157) between Ariosoma anale (147155) and A. coquettei (158) and has fewer LVBV

Fishes of the Western North Atlantic, Part 9

734

10

FIGURE 741. Parabathymyrus oregoni: ANSP 155916, 96 mm SL, Gulf of Mexico (C, D from Smith, 1979: fig. 37). A. Whole view. B. Head. C. Midbody. D. Tail.

myomeres (68-76) than either (90-103 and 8788, respectively). Description (preanal distance measured to point where gut becomes free of body). Total myomeres 153-157 (n = 18), preanal myomeres 146150 (4), predorsal myomeres 146-147 (2), LVBV 68-76 (32). Proportions as % of SL: preanal 9778 (3), HL 3-7 (3), greatest depth 7-9 (3). Body shallower than that of Ariosoma anale. Snout rather elongate, as in Ariosoma selenops. Intestine trails freely behind body for a distance that can exceed body length. Pigmentation. As in Ariosoma balearicum. Size. The largest specimen examined was 279 mm SL (ANSP 156078). Variation. As in Ariosoma anale, the free portion of the gut develops with growth and is frequently damaged. Identification. Of the three bathymyrine leptocephali with a long, free section of the gut, the present one has fewer LVBV myomeres (68-76) than the other two (90-103 and 87-88), and an intermediate number of total myomeres (153-157 vs 147-155 and 158). Parabathymyrus oregoni has fewer precaudal vertebrae (67-70) than Ariosoma anale (83-90) and A. coquettei (75), and an intermediate number of total myomeres (149-155 vs 146-150 and 155-160, respectively). Both the present leptocephalus and adults of P. oregoni

occur widely in the western Atlantic from the Gulf of Mexico to the Guianas. Spawning and Growth. In the western Gulf of Mexico specimens smaller than 20 mm SL were collected in July-August, November, and February. Specimens larger than 100 mm were collected only in February and April. The 279-mm specimen was collected in April. Parabathymyrus oregoni thus seems to have a prolonged spawning period here, at least from July to February. The largest specimen, if it had been spawned the previous summer, was probably about 9 months old. The small size of the sample (32 specimens) and the prolonged spawning season make it difficult to estimate growth rates, but P. oregoni seems to have a relatively long larval life. Remarks. Keller (1976:172) did not describe the pigmentation of the leptocephalus she referred to Parabathymyrus oregoni, but with 157 myomeres it fits that species better than it does Ariosoma anale. Blache (1968a: 702, part; 1977: 102) described a similar leptocephalus from the Gulf of Guinea under the name Ariosoma mellissi; it has fewer myomeres (141-151) than the western Atlantic form. D'Ancona's (1928) Leptocephalus macrenteron from the Red Sea is similar and probably represents Parabathymyrus or Bathymyrus in the Indian Ocean. Mochioka et al. (1982) described

Congrid Leptocephali

735

FIGURE 742. Paraconger: ANSP 155907, 48 mm SL, Gulf of Mexico (B-D from Smith, 1979: fig. 39). A. Whole view. B. Head. C. Tail. D. Upper teeth, left side.

several leptocephali of this type from the western Pacific. Distribution. Gulf of Mexico, Yucatan Channel, Bermuda, southern Caribbean, Guianas. Study Material. 37 specimens, 10-279 mm SL. GULF OF MEXICO: ANSP 154253 (3, 59-75), 154254 (1, 121), 154255 (1, 78), 154256 (1, 81), 154257 (1, 94), 154258 (1, 93), 154259 (1, 95), 154261 (1, 70), 155455 (1, 34), 155456 (3,22-27), 155457 (1,63), 155458 (1,20), 155459 (2, 35-61), 155460 (3, 13-44), 155461 (1, 36), 155462 (2, 40-48), 155463 (1,34), 155464 (1,10), 155465 (1,14), 155467 (1, 36), 155468 (1, 62), 155469 (1, 47), 155916 (1, 101), 156078 (1, 279), 157607 (1, 111). YUCATAN CHANNEL: ANSP 155466 (1,29). COLOMBIA: UMML Pillsbury 383 (1, 77). PANAMA: UMML Pillsbury 343 (1, 53). GUIANAS: UMML Geronimo 7-76 (1, 189).

Paraconger species Figure 742, Table 81 Leptocephalus amphioxus Eigenmann and Kennedy, 1902: 86, fig. 4 (original description, 38°25'N, 72°40'W, holotype USNM 49763). Leptocephalus Michael-Sarsi Lea, 1913: 24, fig. 18, pi. 4, no.

1 (original description, 48°02'N, 39°55'W, holotype ZMUB). Karmovskaya, 1975: 92, fig. 2. Leptocephale 4*. Blache, 1963: 10, pis. 4-5 (metamorphic). Leptocephale 5b. Blache, 1963: 11, pis. 11-12. IParaconger notialis. Castle, 1966a: 25; 1970a: 11. ?Paraconger guianensis. Castle, 1970a: 12. Paraconger caudilimbatus. Keller, 1976: 174. Smith, 1979: 27, fig. 39. Paraconger notialis. Blache, 1977: 112. Paraconger. Smith, 1979: 28. Misidentification: Not Paraconger sp. Karmovskaya, 1975: 92 (identity uncertain; myomere count of 139-140 too high for Paraconger in western North Atlantic).

Distinctive Characters. Leptocephali of Paraconger resemble those of the Conger-Gnathophis-Rhechias-Uroconger group in general body shape and pigmentation. They differ primarily in having a much shorter dorsal fin, which begins far behind midlength. There is no subocular pigment, and the posterior teeth are distinctly blade-shaped (Fig. 742D).

Fishes of the Western North Atlantic, Part 9

736

TABLE 81. Number of specimens, range of SL, and mean SL for leptocephali of Paraconger for different areas and seasons. YC = Yucatan Channel, GM = Gulf of Mexico except Veracruz, HC = high-count form, LC = low-count form. Area and season YC summer YC fall YC winter GM summer HC GM summer LC Veracruz summer GM fall GM winter

n

Range of SL in mm

Mean SLin mm

1 10 4 28 5 3 20 11

13 11-49 33-43 34-90 9-32 36-53 14-59 76-110

13.0 26.0 37.5 46.5 13.6 44.7 37.4 91.7

Description. Total myomeres 119-131 (n = 133), preanal myomeres 92-113 (64), predorsal myomeres 82-97 (23), LVBV 50-61 (41). Proportions as % of SL: preanal 78-96 (133), HL 6-15 (89), greatest depth 10-20 (80). Body moderate, tail not sharply pointed. Gut relatively long and narrow, without loops or swellings. Dorsal fin begins a short distance before anus. Snout moderately long, rather acute. Posterior teeth broad and blade-like (Fig. 742D). Pigmentation. A series of moderately large melanophores just below midlateral line, about one every two or three myomeres, from shortly behind head to end of tail. A series of moderately large melanophores along side of gut tube, alternately on the two sides, from shortly behind head to anus. A few conspicuous melanophores on each side of heart. A few very small melanophores on caudal-fin rays. Size. The largest specimen examined was 110 mm SL (ANSP 154263). Blache (1977: 112, 114) recorded specimens of Paraconger notialis up to 157 mm and a metamorphic specimen of 140 mm. Identification. Very few species of congrid eels in the western North Atlantic have fewer than 130 vertebrae. Among them are Ariosoma balearicum, two species of Paraconger, and two species of Gnathophis. The leptocephali of Ariosoma balearicum and Gnathophis have already been iden-

tified. Some forms of the Rhechias dubia complex also have fewer than 130 myomeres, but they have restricted distributions, and the vertebral counts of the complex as a whole do not match the myomere counts of the present leptocephali. That leaves Paraconger, and here the match is quite good. The composite vertebral count of the western Atlantic species of Paraconger is 121-131, almost identical to the myomere count of the present leptocephali. Blache (1977:112) described similar leptocephali from the Gulf of Guinea and identified them through metamorphic specimens as Paraconger notialis. Specific identification is more difficult. The vertebral counts of the two recognized western Atlantic species overlap: P. caudilimbatus has 121127, and P. guianensis has 126-131. As these counts are based on few specimens (nine and six, respectively), the actual overlap is probably greater. Further complicating the situation is evidence that P. caudilimbatus consists of two sibling species (p. 507). To a certain extent leptocephali can be identified geographically. Specimens collected south and east of Trinidad have 126-130 myomeres and undoubtedly belong to P. guianensis. Leptocephali of the two forms of P. caudilimbatus can be separated in the Gulf of Mexico, because they have different spawning seasons. Both highcount and low-count leptocephali are found in the Straits of Florida as well, but here seasonal spawning patterns cannot be assumed. Without this criterion, the leptocephali cannot confidently be identified except those at the extreme high and low ends of the range. Spawning and Growth. Table 81 shows the size of the leptocephali collected from the Yucatan Channel and the western Gulf of Mexico during the MBI cruises. For the Gulf of Mexico summer specimens the high-count and low-count forms have been separated. The summer specimens from off Veracruz have also been treated separately. In all areas there was a general increase in size from summer to winter. Metamorphosis was complete and leptocephali were essentially absent from the study area by April. In the Yucatan Channel, where only the highcount form is present, small specimens were

Congrid Leptocephali

found both in July-August and in November, indicating a rather long spawning season. In the Gulf of Mexico, the high-count form was present only in the summer. This means that spawning took place sometime after April and that metamorphosis was completed by November. Moreover, no specimens smaller than 34 mm were collected, indicating that spawning had ended by July. This form must therefore spawn in May or June and metamorphose no later than October, giving a larval life of 4 or 5 months. The low-count form spawns in the summer in most of the Gulf of Mexico. In the southernmost part, however, spawning seems to take place from late spring to fall. The specimens collected off Veracruz in July-August were about the same size as those collected elsewhere in November, indicating that they must have been spawned about 3 months earlier. The three smallest specimens collected in November, 14-18 mm SL, were taken at the southern extremity of Campeche Bay. The average SL of the low-count leptocephali progressed from 13.6 mm in July-August to 37.4 mm in November to 91.7 mm in February. The duration of larval life would thus be 6 or 7 months. This is distinctly greater than that of the high-count form and may be another indication that they are different species. Distribution. Entire western tropical Atlantic from Brazil through the Caribbean to the Gulf of Mexico, the Straits of Florida, the Bahamas, Bermuda, the Gulf Stream, and the Sargasso Sea. Also the Gulf of Guinea. Study Material 271 specimens, 7-110 mm SL. GULF STREAM: ANSP 154148 (1, 15-20), 154153 (1, 38), 154165 (1, 58). UMML Pillsbury 107 (1, 20). BERMUDA: ANSP 154156 (1, 70). BAHAMAS: ANSP 154139 (1, 73), 154146 (1, 24), 154147 (1, 44), 154152 (3, 27-52), 154154 (2, 24-27), 154157 (1, 42), 154163 (1, 24), 154164 (1). STRAITS OF FLORIDA: ANSP 154134 (1,46), 154135 (1, 20), 154136 (1, 41), 154137 (1, 59), 154138 (1, 48), 154140 (1, 52), 154141 (2, 39-43), 154142 (1, 44), 154143 (2, 66-80), 154144 (1, 27), 154145 (3, 44-60), 154149 (14, 33-74), 154167 (1,43), 154168 (1,61), 154169 (1,37), 154170 (1, 49), 154171 (1, 120), 154173 (1, 40). UMML Pillsbury 805 (15, 31-68). EASTERN GULF OF MEXICO: ANSP 154166 (12, 26-53), 154172 (30, 27-49). UMML Oregon

737

II 7020 1-8-1 (1, 73), 7020 1-11-1 (2, 25-31), 7020 1-11-2 (1, 35), 7020 1-16-1 (1, 63), 7020 1-21-1 (2, 27-35), 7239 132 (1, 85). UMML Station 1-haul 19-sample 1 (27, 2663), station 1-haul 19-sample 2 (20, 24-51). WESTERN GULF OF MEXICO: ANSP 154262 (1, 96), 154263 (1,110), 154264 (2, 99-101), 154265 (2, 76-89), 154266 (1, 84), 154267 (1,90), 154268 (9,32-53), 154617 (2,55-61), 155470 (1, 45), 155472 (1, 36), 155473 (2, 30-34), 155474 (1, 34), 155476 (3, 14-18), 155478 (1, 43), 155480 (1, 40), 155482 (3, 32-39), 155484 (1, 43), 155542 (3, 46-52), 155543 (4, 26-47), 155544 (2, 36-50), 155545 (3, 7-9), 155546 (1, 13), 155547 (1, 13), 155548 (3, 36-49), 155549 (1, 53), 155550 (1, 42), 155551 (2, 9-12), 155552 (1, 7), 155553 (1, 36), 155554 (3,34-39), 155555 (2,52-58), 155556 (1,46), 155557 (1, 45), 155907 (4, 41-50), 156077 (2, 91-101), 157606 (1, 59). MBI 89 (2, 46-47), 210 (1), 560-562 (2, 78-84), 570 (1), 579 (1), 580 (1), 582 (1), 583 (1), 589 (1), 604 (1). YUCATAN CHANNEL: ANSP 155471 (3,33-37), 155475 (1, 43), 155477 (4, 11-39), 155479 (1, 49), 155481 (3, 2024), 155485 (2, 22-39). LESSER ANTILLES: ANSP 154618 (1, 51). COLOMBIA: ANSP 154150 (2,65-75). GUIANAS: ANSP 154151 (3, 34-51), 154155 (1, 40). BRAZIL: ANSP: 154158 (2, 103-106), 154159 (1, 89), 154160 (1, 62). MCZ RHB 2298 (1, 108). Heteroconger halis (Bohlke, 1957) Nystactichthys halis (Bohlke). Keller, 1976: 182. Misidentification: Not Nystactichthys halis (Bohlke). Smith, 1979: 31 (Heteroconger luteolus).

Distinctive Characters. Leptocephali of Heteroconger resemble those of Paraconger and the Conger group in having moderately large, somatic ventral melanophores and moderately large midlateral melanophores arranged singly rather than in oblique lines. They differ, however, in having a significantly shorter gut and a much longer dorsal fin. The present species has more myomeres than H. luteolus (159-167 vs 137-148). Description. Total myomeres: 159-167 (n = 60), preanal myomeres 82-94 (56), predorsal myomeres 20-30 (54), LVBV 63-69 (45). Proportions as % of SL: preanal 61-85 (53), predorsal 17-30 (24), HL 6-12 (48), greatest depth 10-18 (47). Body moderate, tip of tail moderately blunt; in larger specimens caudal rays short, imbedded in relatively heavy, semi-opaque tissue. Gut simple and relatively short, without loops or thick-

738

Fishes of the Western North Atlantic, Part 9

enings, preanal length about % to % SL; liver rather prominent near anterior end of gut, intestine somewhat thicker than esophagus. Dorsal fin relatively long, beginning at about first quarter of SL. Head and snout moderate. Pigmentation. A series of moderately small melanophores along midlateral line from shortly behind head to tip of tail, every two or three myomeres. A series of small somatic melanophores along gut from shortly behind head to anus, continuing to tip of tail. A few small melanophores lateral to heart and on upper and lower jaws. Very small melanophores on caudalfin base and on posterior dorsal- and anal-fin rays. Size. The largest specimen examined was 75 mm SL (ANSP 154063). Metamorphic specimens were not available, so the maximum size is unknown. It is unlikely to be very much larger than 75 mm, however. Juveniles as small as 78 mm TL have been recorded (ANSP 138794). Variation. One specimen from south of the Dominican Republic (UMML Pillsbury 1389) had 152 myomeres, considerably fewer than any other specimen examined. Identification. Raju (1974b) identified leptocephali of Taenioconger (= Heteroconger, sensu lato) through metamorphic specimens from the eastern Pacific. The present leptocephali are nearly identical and thus represent the genus in the western North Atlantic. Heteroconger halis is the common species in the Caribbean and the Bahamas and has 157-169 vertebrae. Spawning and Growth. During the MBI cruises leptocephali of Heteroconger halis were collected only in July-August and November. Specimens smaller than 20 mm SL were collected in both seasons, and there was little difference in mean SL between summer and fall (22.6 and 22.8 mm, respectively). The absence of specimens in the winter and spring collections indicates that spawning takes place mainly in the summer and fall and that development is relatively rapid. Keller (1976: 230) found a similar pattern around Bermuda. Of 13 specimens collected in the Ocean Acre project, 11 were taken between August and

October. The other two were taken in February and June, and both were large (80.8 and 72.8 mm SL, respectively). Distribution. Caribbean, Bahamas, Straits of Florida, Bermuda. One specimen came from the coast of Brazil (05°43'S, 33°28'W, ANSP 154090). Heteroconger halis is replaced in the Gulf of Mexico by H. luteolus. Study Material 74 specimens, 12-75 mm SL. BAHAMAS: ANSP 154063 (1,75), 154064 (1,56), 154065 (1, 71), 154066 (1, 59), 154070 (1, 45), 154071 (1, 64), 154076 (1, 41), 154077 (1, 54), 154084 (2, 44-55), 154087 (2, 33-38), 154091 (1, 45), 154092 (1, 60), 154093 (2, 3454), 154094 (2, 23-66), 154095 (2, 26-55). STRAITS OF FLORIDA: ANSP 154080 (2,51-59), 154082 (1,49), 154086 (2,36-39). YUCATAN CHANNEL: ANSP 155735 (1,17), 155736 (5, 17-27), 155739 (1, 19), 155742 (1, 20), 155740 (4, 18-25), 155743 (2, 12-20), 155746 (1, 45), 155748 (3, 24-27), 155749 (4, 19-39). JAMAICA: ANSP 154073 (1, 60), HISPANIOLA: ANSP 154069 (1, 56), 154072 (1, 46), 154078 (4, 48-71), 154502 (7, 46-68), UMML Pillsbury 1389 (5,46-66). VIRGIN ISLANDS: ANSP 154079 (1,65). VENEZUELA: ANSP 154062 (1, 55), 154067 (3, 52-74). COLOMBIA: ANSP 154074 (1, 66). NORTHWESTERN CARIBBEAN: ANSP 154068 (1,45). BRAZIL: ANSP 154090 (1, 63).

Heteroconger luteolus Smith, 1989 Figure 743 Nystactichthys halis (not of Bohlke, 1957), Smith, 1979: 31, fig. 46.

Description. Total myomeres 137-148 (n = 44), preanal myomeres 79-87 (46), predorsal myomeres 21-30 (40), LVBV 62-68 (42). Proportions as % of SL: preanal 66-74 (46), predorsal 21-24 (4), HL 6-9 (13), greatest depth 11-13 (14). Otherwise identical to Heteroconger halis. Size. The largest specimen examined was 57 mm SL (MBI 743). In view of its similarity to Heteroconger halis, this species probably metamorphoses at a similar size. Identification. These leptocephali are essentially identical to those of Heteroconger halis except for their distinctly fewer myomeres. The two known adult specimens of H. luteolus came from the Gulf of Mexico, where H. halis is unknown. The present leptocephali occur almost exclusively in the

Congrid Leptocephali

739

FIGURE 743. Heteroconger luteolus: ANSP 157612, 40 mm SL, Gulf of Mexico (B-D from Smith, 1979: fig. 46). A. Whole view. B. Head. C Body near gastric region. D. Tail.

Gulf of Mexico, where leptocephali of H. halts do not occur. The conclusion is inescapable that the present leptocephali represent Heteroconger luteolus. Spawning and Growth. In the Gulf of Mexico leptocephali of this species were collected only in July-August and November. Specimens collected in the summer had a mean SL of 45 mm, and those collected in the fall 41 mm. No specimens smaller than 24 mm were taken. The negligible change in average size from summer to fall indicates that spawning must be more or less continuous over this period. The disappearance of leptocephali in the winter and spring indicates that spawning terminates in the fall and that leptocephali present in November complete their development and metamorphose before February. This would give a relatively short larval life, perhaps 4 months. Distribution. Throughout the Gulf of Mexico. A few specimens were collected in the Straits of Florida and the Gulf Stream, but they could have originated in the Gulf. Study Material. 52 specimens, 24-57 mm SL. GULF STREAM: MCZ 62280 (1, 33), 62294 (1, 33). STRAITS OF FLORIDA: ANSP 158278 (1, 45), 154085 (3,

37-49). GULF OF MEXICO: ANSP 154613 (3, 36-57), 154614 (12, 38-50), 155731 (1, 51), 155732 (1, 45), 155733 (2, 52-53), 155734 (1, 24), 155737 (1, 42), 155738 (2, 4243), 155741 (2, 31-32), 155744 (1, 44), 155745 (2, 29-40), 155747 (1, 46), 155910 (7, 35-48), 157612 (1, 40). MBI743 (3, 36-57), 749 (5, 39-56). UMML Oregon II 7020 2-20-1 (1, 51).

Leptocephalus inferomaculatus Blache, 1977 Figure 744 Pseudoxenomystax sp. Castle, 1970a: 6. Leptocephalus inferomaculatus Blache, 1977: 145 (original description, 00°00', 08°29'E, holotype MNHN).

Distinctive Characters. The relatively short gut and long dorsal fin are shared with the two species of Heteroconger discussed above. The present leptocephalus differs from them mainly in the pattern of lateral pigmentation and the greater number of myomeres. Description. Total myomeres 168-176 (n = 13), preanal myomeres 90-96 (10), predorsal myomeres 30-32 (7), LVBV 70-75 (8). Proportions as % of SL: preanal 56-75 (9), predorsal 19-22 (7), HL 6-10 (10), greatest depth 11-16 (10). Body moderately elongate, tail moderately blunt, caudal rays in large specimens relatively

Fishes of the Western North Atlantic, Part 9

740

10 mm

B

FIGURE 744. Leptocephalus inferomaculatus: ANSP 154500, 88 mm SL, Brazil. A. Whole view. B. Midbody near anus.

short and imbedded in heavy, semi-opaque tissue. Gut simple and relatively short, preanal length about two-thirds SL. Dorsal fin relatively long, originating near anterior fifth of SL. Head and snout moderate. Pigmentation. Lateral pigment consists of one to three moderately small melanophores on myosepta at and immediately below midlateral line, from shortly behind head to end of tail; most myosepta have at least one melanophore, but a few are without any. A paired series of small, widely spaced melanophores beneath esophagus and liver. A paired series of small melanophores level with top of intestine between stomach and anus; a median series of small melanophores ventrally on intestine, staggered on either side of ventral midline. Small melanophores along base of anal fin. Size. The largest specimen examined was 96 mm SL (ANSP 154089). There were three early metamorphic specimens, 75-87 mm SL (ANSP 154501). Variation. These leptocephali have somewhat more myomeres than those described by Blache (1977: 145) from the Gulf of Guinea (166-171) and differ slightly in pigmentation as well. The lateral melanophores as described and illustrated by Blache are somewhat elongate and lie directly

on the myosepta. In the present specimens the melanophores are circular and expanded (though small) and sometimes lie beside rather than directly on the myosepta. Blache also described the esophageal pigment as unpaired, but he did not mention the unpaired midventral intestinal pigment. The leptocephali tentatively referred by Castle (1970a: 6, fig. 3) to Pseudoxenomystax sp. resemble the present leptocephali but have slightly fewer myomeres (168-171 total, 87-90 preanal). The lateral pigment is especially similar. The dorsal fin as illustrated in his figure 3 seems too short for a heterocongrine, but he did not give predorsal myomere counts, and the figure could be in error. The specimens were collected off the hump of Brazil. Identification. The resemblance of this leptocephalus to those of various Heteroconger species is strong enough to suggest that it is a heterocongrine. Particularly significant are the short gut, the long dorsal fin, and the strengthened caudal fin in the metamorphic specimens. The principal difference is the pigmentation. Other known heterocongrine leptocephali have a single row of lateral melanophores, whereas the present leptocephalus has as many as three. Heteroconger camelopardalis (Lubbock) has 171-

Congrid Leptocephali

741

10 mm

B

1 mm

1 mm

FIGURE 745. Congridae, Genus A species A: ANSP 156733, 42 mm SL, Panama. A. Whole view. B. Head. C. Midbody.

173 vertebrae and is known from Ascension Island. The present leptocephali have 168-176 myomeres and are found on both sides of the equatorial Atlantic. There is no hard evidence linking the two, however. In fact, the unique pigmentation of this leptocephalus suggests that it differs substantially from the Heteroconger halis group, possibly at the generic or subgeneric level. The interrelationships of the species currently placed in Heteroconger are not understood well enough yet to predict what variation might be expected in their leptocephali. Distribution. Gulf of Guinea and Brazil. The known specimens have all come from the South Atlantic, but some were taken within a degree of the equator. Etymology. From the Latin infra (below) and macula (spot), referring to the fact that the lateral

melanophores are located slightly below the midlateral line. An adjective. Study Material. 13 specimens, 30-96 mm SL. BRAZIL: ANSP 154088 (3, 84-90), 4°30'S/ 33°30'W, 5 Mar. 1963.154089 (3,87-96), 7°00'S/ 33°30'W, 2 Mar. 1963. 154500 (1, 88), 2°30'S/ 33°30'W, 5 Mar. 1963. 154501 (3, 75-87), 1°30'S, 41°08'W/ 22 Mar. 1963. MCZ 65251 (1, 36), 0°08'S, 34°36'W, 200-220 m, 2 July 1971. 65252 (2, 3036), 0°10'S, 34°43'W, 95-100 m, 3 July 1971.

CONGRIDAE Genus A species A Figure 745 Distinctive Characters. Long dorsal fin. Midlateral melanophores small, located on myosepta, drawn out slightly dorsoventrally. Description. Total myomeres ca 130 (n = 1), preanal myomeres 84 (1), predorsal myomeres

742

Fishes of the Western North Atlantic, Part 9

27 (1), LVBV 67 (1). Proportions as % of SL: preanal 80 (1), HL 9 (1), greatest depth 16 (1). Body moderate, fairly uniform in depth to anus, then narrowing to tail; tail moderate. Gut moderately long, anus at about four-fifths SL; liver rather prominent, gut expands noticeably between esophagus and intestine. Dorsal fin long, begins in anterior quarter of SL. Head and snout rather long, acute in profile. Pigmentation. A series of small melanophores just below midlateral line exactly on myosepta, drawn out dorsoventrally along the myoseptum; usually one such melanophore per myoseptum, but occasionally a second melanophore is present, usually below main one. A single median series of very small melanophores along ventral midline from heart to anus, except on liver, where series expands to form a triangular cluster. A few small melanophores on heart, and a few more laterally at posterior end of gut. Very small melanophores on base of anal fin and on caudal fin. A few very small melanophores on upper jaw, and some pigment over eye. Size. The single specimen is 42 mm SL. Identification. About the only congrid leptocephali that have such a long dorsal fin are the heterocongrines. The present leptocephalus resembles heterocongrines further in the prominent liver and the expansion of the gut behind it. The lateral pigment is remarkably similar to that illustrated by Blache (1977:146, fig. 48d) for Leptocephalus inferomaculatus (although not for the specimens of that species examined here). The present leptocephalus differs from L. inferomaculatus in having far fewer myomeres, and its ventral pigment is located on the bottom of the gut rather than the top, as illustrated by Blache (1977: 146, fig. 48d). The gut is longer than that of other heterocongrines examined, and the snout is more prolonged. Nevertheless, enough resemblances exist to suggest that the leptocephalus might be a heterocongrine. Unfortunately, the only known specimen is too small to show the reduction of the caudal fin characteristic of heterocongrine leptocephali. Distribution. The specimen was collected in the Golfo de los Mosquitos, Panama.

Study Material. One specimen, 42 mm SL. PANAMA: ANSP 156733, Pillsbury 441, 9°05.6'N/ 81°06.9'W, 20 m, 1.8 m IKMT, 21 July 1966.

Conger oceanicus (Mitchill, 1818) Conger oceanicus. Schmidt, 1931b: 602. Bigelow and Schroeder, 1953: 156, fig. 70B. Misidentification: Not Conger oceanicus (Mitchill). Smith, 1979: 28, fig. 40 (Conger triporiceps).

Distinctive Characters. Leptocephali of Conger are unusual among congrids in that they generally lack midlateral pigment, although large individuals of C. oceanicus do develop this character. Leptocephali of Conger and Gnathophis have a less acute tail than those of other congrine genera. Conger leptocephali are distinguished from Gnathophis by the shorter, less acute snout and a difference in the shape of the hypural. The three species of Conger in the western North Atlantic can be distinguished by their myomere counts. Description. Total myomeres 140-148 (n = 41), preanal myomeres 113-124 (38), predorsal myomeres 67-81 (33), LVBV 51-55 (12). Proportions as % of SL: preanal 88-97 (38), predorsal 61-69 (2), HL 6-10 (36), greatest depth 8-14 (36). Body moderately elongate, deepest point slightly behind mid-length; tail moderate. Gut long and simple. Dorsal fin originates about twothirds of the way from head to tail. Head and snout moderately short. Dorsal profile of hypural not bent sharply upward posteriorly. Pigmentation. Lateral pigment variable; when present it consists of a series of moderately large melanophores along midlateral line. A paired series of moderately small somatic melanophores along top of gut from shortly behind head to anus. A crescentic patch of pigment below eye. A few very small melanophores on caudal-fin rays. Size. Maximum size appears to be about 100 mm SL. Variation. Lateral pigment is present only in

Congrid Leptocephali large individuals. The smallest specimen examined that showed any sign of lateral pigment was 64 mm SL (ANSP 154733), and it had only a few melanophores behind the anus. The specimens with conspicuous lateral pigment were all larger than 80 mm except a metamorphic specimen of 75 mm (ANSP 154751). The largest premetamorphic specimen without lateral pigment was 83 mm (ANSP 154739). When fully developed, the melanophores are most closely spaced posteriorly. Identification. The larva of the closely related Conger conger was the first leptocephalus to be identified with an adult (Delage, 1886). The close match of myomere/vertebral counts and the presence of metamorphic specimens confirm the identity of the leptocephali described here as Conger oceanicus. Spawning and Growth. Leptocephali of Conger oceanicus show no clearly seasonal pattern of occurrence, hence the duration of larval life is difficult to assess. If the species spawns in the West Indian region, leptocephali probably need about as much time as Anguilla rostrata does to return to the continent. This would be approximately 7 months. Distribution. Northern Caribbean, eastern Gulf of Mexico, Straits of Florida, Bahamas, Gulf Stream, Sargasso Sea. Metamorphic specimens are found along the Atlantic coast of the United States as far north as the Gulf of Maine. Schmidt (1931b: 603) stated that during the Danish eel expeditions "quite tiny larvae" of Conger oceanicus were found in the West Indies, indicating that the species spawned in that area. No leptocephali smaller than 29 mm were present among the material examined here, but the pattern of distribution supports Schmidt's conclusion. Adults of Conger oceanicus inhabit only the Atlantic continental shelf of the United States. The presence of leptocephali in the Caribbean and the Bahamas would be difficult to explain if the adults did not go to some such southern area to spawn. Leptocephali of Conger oceanicus seem to be absent from the western Gulf of Mexico; none were collected on the MBI cruises.

743

Study Material 57 specimens, 29-99 mm SL. SARGASSO SEA: ISH Anton Dohrn: 5527 IK-1 (1,42), 5689 IK-25 (1, 42), 5698 IK-27 (1, 45), 5717 IK-31 (1, 36), 5725 IK-33 (3, 27-33), 5738 IK-35 (4, 27-61), 5738 IK-37 (2, 35-52), 5746 IK-39 (1, 50). GULF STREAM: ANSP 154746 (1,99), 154750 (1,69), 154751 (1, 75). BAHAMAS: ANSP 154732 (4, 28-73), 154734 (2, 49-82), 154736 (2, 65-66), 154738 (1, 75). STRAITS OF FLORIDA: ANSP 154733 (4, 63-71), 154735 (1, 64), 154737 (1, 97), 154739 (1, 82), 154740 (2, 35-59), 154741 (2, 80-82), 154742 (1, 57), 154743 (1,39), 154744 (2,52-65), 154745 (1,49), 154747 (1, 59), 154748 (1,56), 154749 (1, 35). GULF OF MEXICO: ANSP 154753 (1, 58), 154754 (1, 37), 154755 (3, 34-57), 154756 (1,59). JAMAICA: ANSP 154752 (1,55). Alaminos sta. 3, 6-7 May 1973 (5, 59-81; lost).

Conger triporiceps Kanazawa, 1958 Figure 746 Conger triporiceps. Keller, 1976: 177 (?). Conger oceanicus (not of Mitchill, 1818). Smith, 1979: 28, fig. 40.

Distinctive Characters. Like Conger oceanicus but 150-158 myomeres. Lateral pigment always absent. Description. Total myomeres 150-158 (n = 44), preanal myomeres 124-133 (35), predorsal myomeres 65-78 (17), LVBV 54-70 (22). Proportions as % of SL: preanal 90-94 (30), predorsal 57-63 (2), HL 6-13 (25), greatest depth 9-15 (24). Otherwise identical to Conger oceanicus, but lateral pigment never present. Size. The largest specimen examined was 110 mm SL (ANSP 154603), and it was metamorphosing. Other metamorphic specimens were 88105 mm SL. Variation. Specimens from the Gulf of Mexico have slightly fewer myomeres on average (150157) than those from the Caribbean and Straits of Florida (153-158). Identification. These leptocephali are obviously Conger, and their myomere count is similar to the vertebral count of C. triporiceps (156-160). Spawning and Growth. In the western Gulf of Mexico, 22 specimens were collected in February. They ranged from 25 to 83 mm and had a mean SL of 52.6 mm. In April only four specimens were collected, 80-87 mm SL. No specimens were taken in the summer or fall. This means that

Fishes of the Western North Atlantic, Part 9

744

10

FIGURE 746. Conger triporiceps (B, D, E from Smith, 1979: fig. 40): A. ANSP 155377, 17 mm SL, Yucatan Channel. B. ANSP 154767, 85 mm SL, Gulf of Mexico; head. C. Same; whole view. D. Same; midbody showing vertical blood vessel. E. Same; tail.

spawning takes place after November and that the leptocephali grow to about 53 mm SL by February. Two months later the average size has increased by 30 mm. Sometime in the following 2 months metamorphosis occurs. Thus the duration of larval life must be 5 or 6 months. Distribution. Northern and southern Caribbean, Gulf of Mexico, Straits of Florida, Bahamas, Gulf Stream, Sargasso Sea.

51), 155381 (1, 51), 155382 (2, 56), 155383 (1, 59), 157616 (1, 87). MBI 510 (5, 25-70), 520 (1). YUCATAN CHANNEL: ANSP 154763 (1, 75), 154764 (1, 66), 155373 (1,95), 155374 (1, 47), 155377 (1, 18), 155378 (1, 10), 155379 (1, 18), 158288 (1,17). HISPANIOLA: ANSP 154592 (4,102105), 154594 (1, 93), 154596 (1, 52), 154603 (1, 109). VIRGIN ISLANDS: ANSP 154591 (1,31). COLOMBIA: ANSP 154593 (1, 98).

Study Material. 68 specimens, 10-110 mm SL. SARGASSO SEA: ISH Anton Dohrn: 5653 IK-17 (1, 39), 5684 IK-23 (1, 124), 5738 IK-35 (3, 46-101). GULF STREAM: ANSP 154607 (1, 77), 154609 (1, 71). BAHAMAS: ANSP 154304 (2, 44-67), 154590 (1, 38), 154595 (1, 49), 154597 (1, 87), 154598 (1, 28), 154600 (1, 68), 154602 (1, 91), 154605 (1, 65), 155064 (2, 25-46). STRAITS OF FLORIDA: ANSP 154599 (1, 62), 154601 (1, 44), 154606 (1, 28). GULF OF MEXICO: ANSP: 154604 (1,90), 154608 (1, 86), 154760 (2, 49-66), 154761 (1, 80), 154762 (1, 75), 154765 (2, 57-83), 154766 (1, 89), 154767 (1, 85), 154768 (1, 65), 155375 (1, 55), 155376 (4, 26-56), 155380 (3, 40-

Distinctive Characters. Like Conger oceanicus but 133-135 myomeres. Description. Total myomeres ca 133-135 (n = 2), preanal myomeres 111-113 (2), predorsal myomeres 66 (1), LVBV 50 (3). Predorsal length ca 58-69% SL (2). Otherwise identical to Conger oceanicus and C. triporiceps. No specimen larger than 74 mm was available, and it is not known whether lateral pigment would develop at a later stage.

Conger esculentus Poey, 1858

Congrid Leptocephali

—^"

745

* • • * • • • • V—' -I.

FIGURE 747. Gnathophis (C, D from Smith, 1979: fig. 41): A. ANSP 158289, 18 mm SL, Yucatan Channel. B. ANSP 155884, 64 mm SL, Gulf of Mexico. C. Same; head. D. Same; intestine. E. Same; tail.

Identification. Conger esculentus has 136-137 vertebrae and is found in the West Indies and Bermuda. The myomere counts of the present leptocephali are slightly lower than this, but they were based on two specimens and were only approximate. Distribution. The three specimens were collected off the south coast of the Dominican Republic and in the Virgin Islands. Study Material. 3 specimens, 37-74 mm SL. HISPANIOLA: ANSP 154758 (1, 52), 18°12.8'N, 69°16.7'W, ca 35 m, 10 July 1971. ANSP 154759 (1, 74), 18°16.1'N, 69°13.7'W, ca 100 m, 10 July 1971. VIRGIN ISLANDS: ANSP 154757 (1, 37), 17°56.6'N, 65°06.3'W, ca 50m, 11-12 July 1971.

Gnathophis species Figure 747 Gnathophis sp. I. Keller, 1976: 176. Gnathophis sp. II. Keller, 1976: 176. Gnathophis. Smith, 1979: 28, fig. 41.

Misidentification: Not Gnathophis mystax Delaroche. Karmovskaya, 1975:90, fig. 2 (identity uncertain, myomere count of 143-147 too high for Gnathophis in western Atlantic).

Distinctive Characters. Leptocephali of Gnathophis differ from those of Conger primarily in the longer, more acute snout and in the shape of the hypural. Midlateral pigment is absent or reduced to a few small melanophores on the posterior part of the body. Description. Total myomeres 126-141 (n = 63), preanal myomeres 101-125 (58), predorsal myomeres 72-102 (76), LVBV 43-47 (32). Proportions as % of SL: preanal 90-97 (61), predorsal 72-81 (13), HL 6-14 (67), greatest depth 10-18 (63). Body moderately elongate, deepest at about mid-length; tail moderate, not sharply pointed. Gut long and simple, anus within one-tenth SL of end of tail. Dorsal fin begins about three quarters of the way from head to tail. Head and snout rather elongate, sharply conical in profile. Hy-

746

Fishes of the Western North Atlantic, Part 9

pural relatively short and deep, dorsal profile bends upward sharply posteriorly, becoming almost vertical (Fig. 747E). Pigmentation. Lateral pigment usually absent, but some specimens have an irregular series of small melanophores just below midlateral line, generally on posterior half of body. A paired series of moderately small somatic melanophores along top of gut, from shortly behind head to tail. A few small melanophores on each side of heart. A crescentic patch of pigment below eye. Very small melanophores on base of caudal- and anal-fin rays. Size. The largest specimen examined was 124 mm SL (ISH Anton Dohrn 5760). The only specimen that appeared to be approaching metamorphosis was 82 mm (ANSP 154498). Variation. The presence or absence of lateral pigment does not seem to be related to size. Specimens with lateral pigment ranged from 35 mm to 77 mm SL, those without it from 15 mm to 124 mm. Identification. The leptocephalus of Gnathophis mystax from the Mediterranean has been known for many years. The present leptocephali are essentially identical and must therefore represent Gnathophis in the western Atlantic. The vertebral counts of the western Atlantic species (125-138) agree well with the myomere counts of the leptocephali. Indeed, there is no other genus whose species fit the myomere counts of these leptocephali. Specific identification is more difficult. The vertebral counts of Gnathophis bracheatopos and G. bathytopos overlap (125-130 and 128-133, respectively), and their leptocephali would be difficult to separate on myomere count alone. Gnathophis tritos has distinctly more vertebrae (136-138), but it is known from only three specimens. The myomere counts of the leptocephali show a broad, highly skewed distribution with a conspicuous peak around 137-138. That peak could represent G. tritos, but corroborating evidence is lacking. Spawning and Growth. There is no clear evidence for a seasonal spawning pattern in Gnathophis. In the Gulf of Mexico, leptocephali smaller than 20 mm were collected in April, July, and

November. The duration of larval life canrot be estimated. Distribution. From the Gulf of Mexico, Straits of Florida, Bahamas, Bermuda, and Sargasso Sea south through the Caribbean to Suriname and Brazil. Adults of Gnathophis are known only from the southeastern coast of the United States, the eastern Gulf of Mexico, the Caribbean coast of the Yucatan, and the Santaren Channel. The presence of leptocephali virtually throughout the western Atlantic suggests either that the true distributions are much wider or that at least some species make long spawning migrations, like Conger and Anguilla. Unlike the latter two, however, small leptocephali of Gnathopis (less than 20 mm SL) are found in places like the Gulf of Mexico, the Florida Straits, and the Gulf Stream north of the Bahamas, so at least some individuals spawn relatively close to home. A similar discrepancy occurs in the eastern Atlantic. Blache (1977: 136) recorded leptocephali of Gnathophis from the Gulf of Guinea, although adults are unknown from the area. Study Material. 133 specimens, 15-124 mm SL. SARGASSO SEA: ANSP 154109 (1, 65). ISH Anton Dohrn 5527 IK-1 (1,65), 5538 IK-2 (3, 91-120), 5550 MT-3 (5, 57-110), 5576 IK-5 (1, 61), 5562 IK-4 (1, 63), 5588 IK-6 (2, 63-64), 5596 IK-7 (1, 84), 5603 IK-8 (4, 65-70), 5632 IK-14 (1, 81), 5632 MT-11 (4, 71-85), 5653 IK-17 (7, 5889), 5684 IK-23 (8, 67-97), 5689 IK-25 (1, 72), 5709 IK-29 (1, 63), 5717 IK-31 (1, 120), 5724 MT-18 (1), 5738 IK-35 (4, 61-108), 5750 IK-40 (1, 45), 5760 MT-21 (2, 102-124). GULF STREAM: ANSP 154105 (1, 16), 154128 (4, 32-63). BERMUDA: ANSP 154099 (2, 45-46), 154104 (1, 73), 154110 (2, 62-66), 154176 (4, 55-80). BERMUDA-BAHAMAS: ANSP 154098 (2,60-61), 154107 (1,102), 154133 (1, 94). BAHAMAS: ANSP 154097 (1, 71), 154106 (1, 52), 154108 (1, 64), 154120 (1, 59), 154121 (1, 38), 155389 (1, 74). STRAITS OF FLORIDA: ANSP 154113 (1,38), 154114 (1, 44), 154115 (1, 54), 154116 (1, 33), 154117 (1, 48), 154118 (4,31-84), 154119 (7,18-80), 154122 (1,32), 154123 (2, 27-38), 154124 (1, 38), 154126 (1, 41), 154127 (1, 40), 154131 (1, 36), 157615 (1, 52). UMML Gerda 84 (1, 33). GULF OF MEXICO: ANSP: 154129 (1, 38), 154130 (1, 58), 155385 (1, 68), 155386 (1, 22), 155388 (1, 15), 154497 (1, 76), 154496 (1,59), 155884 (1,64). UMML Oregon II7020 1-16-2 (1, 36). YUCATAN CHANNEL: ANSP 155387 (1, 34), 155909 (2, 16-55), 158289 (1, 18). HISPANIOLA: ANSP 154132 (1,78), 154498 (1,82), 154499 (1,40). PUER-

Congrid Leptocephali

747

10

FIGURE 748. Rhynchoconger flavus (D-F from Smith, 1979: fig. 44): A. ANSP 155355, 15 mm SL, Gulf of Mexico. B. Same; head. C. ANSP 154441,73 mm SL, Gulf of Mexico. D. Same; head. E. Same; lateral body wall showing subcutaneous melanophores. F. Same; tail. TO RICO: ANSP 154100 (8, 49-81), 154101 (3, 66-81), 154111 (1, 77). VIRGIN ISLANDS: ANSP 154103 (1, 32). VENEZUELA: ANSP 154112 (1, 43). COLOMBIA: ANSP 154096 (1, 59). GUIANAS: ANSP 154102 (2,33-64). BRAZIL: ANSP 154125 (1, 45).

Rhynchoconger flavus (Goode and Bean, 1896) Figures 748, 749 Leptocephalus enchodon Lea, 1913: 25. Karmovskaya, 1975: 91, fig. 2. Keller, 1976: 180. Hildebrandia flava. Blache, 1977:131. Smith, 1979: 30, fig. 44.

Distinctive Characters. The subcutaneous lateral melanophores distinguish leptocephali of Rhynchoconger from all other western Atlantic congrid leptocephali. The leptocephalus of R. flavus differs from other leptocephali of the Conger group in lacking the crescentic suborbital pigment patch. It further differs from Rhynchoconger gracilior/guppyi in having a more uneven row of midlateral melanophores.

Description. Total myomeres 153-170 (n = 133), preanal myomeres 102-132 (145), predorsal myomeres 49-62 (126), LVBV 44-51 (85). Proportions as % of SL: preanal 83-95 (144), predorsal 42-58 (31), HL 5-13 (115), greatest depth 10-19 (84). Body moderately elongate, deepest point slightly behind mid-length; tail acute. Gut long and simple, anus at about nine-tenths SL. Dorsal fin originates near midbody. Head moderately short, dorsal profile convex in larger specimens. Pigmentation. An irregular, staggered row of moderately large melanophores just below midlateral line, spaced about every two to five myomeres, beneath surface of skin and muscle. A paired row of moderately small somatic melanophores along side of gut from shortly behind head to anus. Two or three small melanophores lateral to heart. Very small melanophores on analand caudal-fin rays. No pigment beneath eye or on jaws or palate. Size. The largest specimen examined was 117 mm SL (ANSP 154427). Two early metamorphic

Fishes of the Western North Atlantic, Part 9

748

N 302010-

30-

Winter

2010-

4030-

Spring

2010-

Summer 2010-

50mm

100mm

SL

FIGURE 749. Size distribution of leptocephali of Rhynchoconger flavus from the northern Gulf of Mexico over four seasons.

specimens were 100 and 104 mm SL (ANSP 154569, 154578). Variation. Specimens from south and east of Trinidad have significantly more myomeres than those from the Caribbean and more northerly areas. Only eight specimens were available from the former area, and only approximate counts could be made. Nevertheless, they all had between 165 and 170 myomeres as opposed to about 156-165 in specimens from the Caribbean and north. A specimen from just west of Grenada (ANSP 154187) had 168 myomeres and could belong to the southern form as well. The same geographical variation occurs in the vertebral counts of adults (see p. 529). Identification. The identification of this leptocephalus is based primarily on the close match of myomere/vertebral number, geographic dis-

tribution, and relative abundance. The leptocephalus is one of the most common in the western Atlantic and is especially abundant in the western Gulf of Mexico. Rhynchoconger flavus is a common species and is abundant in the western Gulf of Mexico. The myomere counts of the leptocephali agree closely with the vertebral counts of adult Rhynchoconger flavus and show the same pattern of geographic variation, with higher values south and east of Trinidad. Unlike many congrid eels, juvenile R. flavus show no remnants of the lateral pigment of the leptocephalus. This is probably because the lateral melanophores are subcutaneous and are buried beneath opaque skin after metamorphosis. Spawning and Growth. There seems to be considerable local variation in spawning time. In the Yucatan Channel, specimens smaller than 20 nun SL were found in the summer and fall, but the sample size was very small (eight specimens). In the southern Gulf of Mexico such small specimens were found in the fall, winter, and spring, and in the northern Gulf in the summer and fall. A spawning class can generally be followed for three seasons, in some cases four. Among specimens collected off the Texas coast, for example, the average size increased progressively from November to April (Fig. 749). The scarcity of large specimens in the summer together with the essentially unchanged mean SL suggest that metamorphosis had been largely completed by August. Spawning in this area thus seems to occur from about August to November, with most specimens metamorphosing the following year sometime between April and August. The length of larval life would thus be about 9-12 months. Distribution. From the Gulf of Mexico, the Straits of Florida, and the Gulf Stream south through the Caribbean to the Guianas. It is more common in the southern Caribbean than in the Antilles, although it has been collected around the Dominican Republic and Jamaica. It is also more common in the western than the eastern Gulf of Mexico. These patterns parallel the distribution of the adults. Individuals caught in the Gulf Stream can be carried long distances; several specimens were found in the central Atlantic

Congrid Leptocephali near 38°N, 40°W/ including the type of Lea's Leptocephalus enchodon. Nevertheless, the leptocephali are not common around Bermuda or in the Sargasso Sea. This may reflect the scarcity of adults in the Antilles, and it may indicate that the adults do not make long spawning migrations. Rhynchoconger flavus was the most abundant leptocephalus collected in the western Gulf of Mexico during the MBI cruises. Study Material. 2677 specimens, 6-117 mm SL. CENTRAL ATLANTIC: ANSP 154211 (1, 104), 154212 (1, 105), 154213 (1, 106). SARGASSO SEA: ISH Anton Dohrn 5756IK-41 (1, 86). GULF STREAM: ANSP 154581 (1, 85), 154583 (1, 92). STRAITS OF FLORIDA: ANSP 154191 (1, 69), 154192 (1, 67), 154193 (1, 39), 154194 (1, 67), 154195 (1, 63), 154198 (1, 37), 154200 (1, 78), 154201 (1, 53), 154202 (2, 67-80), 154204 (2, 59-62), 154205 (2, 35-53), 154206 (1,76), 154209 (1,53), 154218 (1,61), 154220 (1, 60), EASTERN GULF OF MEXICO: ANSP 154210 (3, 75-78), 154214 (1, 72), 154215 (1, 87), 154216 (2, 77-86), 154217 (1, 54), 154580 (2, 49-92), 154582 (1, 42). WESTERN GULF OF MEXICO: ANSP 154402 (1, 98), 154403 (1, 96), 154404 (3, 7-97), 154405 (3, 101-105), 154406 (8, 79-103), 154407 (2, 67-86), 154408 (4, 46-54), 154409 (1, 84), 154410 (2,96-98), 154411 (3,45-85), 154412 (1), 154413 (7, 25-91), 154414 (7, 42-82), 154415 (3, 45-82), 154416 (16,25-89), 154417 (3, 50-66), 154418 (2, 45-52), 154419 (24,20-85), 154420 (5,54-72), 154421 (23,28-77), 154422 (3,36-61), 154423 (1,100), 154425 (4,32-111), 154426 (28, 11-53), 154427 (1, 117), 154428 (1, 106), 154429 (12, 2435), 154430 (9, 39-54), 154431 (18, 39-81), 154432 (4, 37105), 154433 (6, 86-94), 154434 (1, 90), 154435 (7, 32-85), 154436 (15, 37-74), 154437 (4, 66-89), 154438 (9, 31-46), 154439 (4,45-76), 154440 (4,80-105), 154441 (14, 38-76), 154442 (1, 94), 154443 (8, 38-68), 154444 (16, 24-52), 154445 (5,39-60), 154446 (2,43-75), 154447 (1, 82), 154448 (32,12-45), 154449 (2, 45-52), 154450 (5, 43-71), 155044 (13,42-108), 155058 (4,80-102), 155345 (8,27-41), 155346 (4, 31-52), 155347 (2, 33-34), 155348 (3, 13-51), 155349 (1, 13), 155350 (7, 28-53), 155351 (3, 28-30), 155352 (1, 38), 155353 (1, 39), 155354 (6, 20-37), 155355 (51, 8-52), 155356 (2, 22-26), 155358 (2, 7-9), 155359 (6, 26-47), 155360 (1, 141), 155361 (2, 39-41), 155362 (28, 8-13), 155363 (2,11-14), 155464 (2,20-42), 155365 (1,33), 155366 (5, 39-48), 155368 (51, 9-37), 155369 (9, 22-55), 155370 (1, 186), 155371 (2, 31-41), 155372 (7, 27-51), 155526 (3, 8), 155527 (1, 53), 155528 (2, 28-34) 155529 (2, 50-52), 155530 (1, 54), 155531 (2, 45-47), 155533 (1, 7), 155534 (3, 68-87), 155536 (7, 47-64), 155537 (3, 6-10), 155539 (2, 45-52), 155540 (10, 35-60), 155541 (1, 33), 155925 (22, 23-91), 155926 (21, 42-88), 155928 (73, 34-102), 155927

749

(31,45-94), 155929 (5,87-104), 155930 (46,23-72), 155931 (18,44-102), 155939(74,33-67), 155932 (6,79-91), 155933 (30, 46-100), 155934 (24, 48-95), 155935 (31, 22-100), 155936 (7, 74-102), 155937 (30, 43-98), 155938 (3, 90102), 155940 (20, 33-76), 155941 (6, 90-104), 155942 (14, 43-99), 155943 (49, 28-71), 155944 (21, 40-95), 155945 (65,30-88), 155946 (38,44-102), 155947 (31,32-93), 155948 (32,23-82), 155949 (12,24-94), 155950 (24,42-100), 155951 (96,42-96), 155974 (15,57-80), 156037 (41,40-94), 156038 (6, 9-102), 156039 (114, 6-48), 156040 (12,19-97), 156041 (5, 15-95), 156042 (2, 91-97), 156043 (7, 85-99), 156045 (10,62-101), 156046 (12,10-98), 156047 (9,49-95), 156048 (14, 34-101), 156049 (12, 20-79), 156050 (12, 42-102), 156051 (14, 56-106), 156052 (21, 42-73), 156053 (6, 8198), 156054 (64,9-90), 156055 (21,11-86), 156056 (43,6094), 156057 (38, 21-98), 156059 (34, 51-97), 156060 (15, 9-99), 156061 (59,35-78), 156062 (11,62-92), 156063 (70, 21-95), 156064 (3, 80-90), 156065 (31, 40-100), 156066 (48, 48-113), 156067 (40, 51-86). MBI 91 (6, 14-46), 208 (1), 345 (1, 97), 563 (1), 584 (1), 590 (4), 742 (13, 14-76). YUCATAN CHANNEL: ANSP 154424 (1, 78), 155357 (2, 9-17), 155367 (1,15), 155525 (1,56), 155532 (1,35), 155535 (1, 16), 155538 (1, 49). JAMAICA: ANSP 154575 (2, 4584). HISPANIOLA: ANSP 154180 (1, 38), 154563 (3, 2838), 154572 (1,71), 154577 (4, 62-74). LESSER ANTILLES: ANSP 154187 (1, 56). COLOMBIA: ANSP 154569 (1, 95). UMML Oregon II 7343-156 (1, 73). PANAMA: ANSP 154182 (2, 83-84), 154183 (1, 100), 154184 (2, 74-90), 154185 (1, 62), 154186 (24, 75-95), 154189 (1, 82), 154190 (1, 99), 154564(5,89-100), 154566 (1, 96), 154578 (1,104). NICARAGUA: ANSP 154562 (2, 31-39), 154570 (1, 80), 154576 (1,71), GUIANAS: ANSP 154567 (7,36-77), 154568 (1, 74).

Rhynchoconger gracilior (Ginsburg, 1951)

and/or

Rhynchoconger guppyi (Norman, 1925) Figure 750 Distinctive Characters. Like Rhynchoconger flas, this leptocephalus has subcutaneous lateral melanophores, but they are arranged in a more even row. The present leptocephalus has more myomeres than R. flavus, and some trace of suborbital pigment is often present. It also has melanophores on the jaws and palate, especially in smaller specimens, a character lacking in R. flavus. Larger specimens are somewhat shallower and more slender in appearance than R. flavus. Description. Total myomeres 172-182 (n = 37), preanal myomeres 102-130 (39), predorsal myo-

Fishes of the Western North Atlantic, Part 9

750

10

FIGURE 750. Rhynchoconger gracilior: A. ANSP 154292, 16 mm SL, Gulf of Mexico. B. Same; head. C. ANSP 154295, 65 mm SL, Gulf of Mexico.

meres 48-59 (29), LVBV 43-49 (26). Proportions as % of SL: preanal 81-89 (35), predorsal 44-54 (10), HL 6-10 (18), greatest depth 10-13 (21). Form and proportions of body and head similar to those of Rhynchoconger flavus, with the exceptions noted above. Pigmentation. A single row of moderately large melanophores just below midlateral line, spaced about every three or four myomeres, beneath surface of skin and muscle. A paired row of moderately small somatic melanophores along side of gut tube, from shortly behind head to anus, somewhat more widely spaced than those of R. flavus. Two or three small melanophores on heart. Melanophores on palate and lower jaw in small specimens. An indistinct crescentic patch of pigment below eye, especially in small specimens. Very small melanophores on caudal- and analfin rays. Size. The largest specimen examined was 109 mm SL (ANSP 154573). Identification. This leptocephalus closely resembles that of Rhynchoconger flavus, including the subcutaneous lateral melanophores. The other western Atlantic species of Rhynchoconger, R. gracilior and R. guppyi, have overlapping vertebral counts (175-182 and 173-178, respectively), and by that criterion the present leptocephali could represent either or both. Rhynchoconger gracilior is more common and widespread than

R. guppyi, and on that basis most of the leptocephali probably belong to it. In particular, R. guppyi has not been recorded from the Gulf of Mexico, where the present leptocephali are fairly common. Among the MBI collections these leptocephali were found predominantly to the north and west of Campeche Bank. Adults of R gracilior are found in the eastern Gulf of Mexico and on Campeche Bank, but not along the western margin of the Gulf. The distribution of the leptocephali in the Gulf of Mexico is thus congruent with that of adult R gracilior. In addition, the largest of the Gulf leptocephali are clearly developing the fourth supraorbital pore, a diagnostic character of R. gracilior. Outside the Gulf, identification is less certain. Spawning and Growth. The size distribution of the leptocephali suggests that the spawning period is extended. In the Gulf of Mexico specimens smaller than 20 mm SL were collected only in the winter, but individuals in the 20-30-mm range were taken in the summer and fall as well. Seventy-one specimens collected in February ranged from 13 to 80 mm SL. The duration of larval life cannot be estimated. Distribution. Eastern and western Caribbean, Gulf of Mexico, Straits of Florida, Bermuda-Bahamas area. Study Material. 104 specimens, 13-82 mm SL. BERMUDA-BAHAMAS: ANSP 154188 (1, 77). BA-

Congrid Leptocephali

751

10

FIGURE 751. Uroconger syringinus (C-E from Smith, 1979: fig. 42): A. ANSP 158285, 20 mm SL. B. ANSP 158286, 93 mm SL. C. Same; head. D. Same; midbody. E. Same; tail. HAMAS: UMML Oregon II 7239-148 (1, 35). STRAITS OF FLORIDA: ANSP 154197 (1,70), 154203 (1,45), 154219 (1, 56). GULF OF MEXICO: ANSP 154291 (7, 18-81), 154292 (21, 13-65), 154293 (1, 63), 154294 (8, 39-73), 154295 (12, 29-82), 154296 (1, 59), 154297 (1, 62), 154298 (1, 75), 154299 (20, 20-80), 156157 (3, 27-29), 156158 (1, 32), 156159 (1,23), 156160 (1,44), 156161 (3,26-42), 156162 (2, 24-26), 156163 (1, 60), 156164 (2, 32-37), 156165 (3, 32-47), 156166 (1, 49), 157620 (1, 66), 158275 (1, 68). HISPANIOLA: ANSP 154571 (1, 70), 158282 (1, 46). LESSER ANTILLES: ANSP 154573 (1, 109), 154579 (1, 66). COLOMBIA: ANSP 158283 (1, 57). UMML Pillsbury 384 (2, 64-70).

Uroconger syringinus Ginsburg, 1954 Figure 751 Leptocephale 5a*V Blache, 1963: 12. Leptocephale 5a***. Blache, 1963: 12, pi. X. Uroconger vicinus (not of Vaillant, 1888). Karmovskaya, 1975: 92, fig. 2. Uroconger syringinus. Keller, 1976: 179. Blache, 1977:123, figs. 39-40. Smith, 1979: 29, fig. 42.

Distinctive Characters. Leptocephali of this species are characterized by a single row of midlateral melanophores and approximately 216-227

myomeres. The only other congrid species in the western Atlantic with more than 200 vertebrae is Xenomystax congroides, and its leptocephalus is very different in form and pigmentation. Description. Total myomeres 216-227 (n = 14), preanal myomeres 154-175 (28), predorsal myomeres 64-77 (22), LVBV 65-75 (27). Proportions as % of SL: preanal 85-97 (26), predorsal 44-51 (9), HL 4-9 (32), greatest depth 5-15 (31). Body elongate, tail acute. Gut long and simple, anus within about one-tenth SL of tip of tail. Dorsal fin begins at or slightly before midbody. Head and snout rather short. Pigmentation. A row of moderately large melanophores along midlateral line, from shortly behind head to end of tail, spaced every one to two myomeres. A paired series of moderately large somatic melanophores along top of gut from shortly behind head to anus, continuing behind anus as an irregular single or double row of smaller melanophores to tip of tail. A few small melanophores lateral to heart and on upper jaw. A crescentic patch of pigment below eye. Size. The largest specimen examined was 134

752

Fishes of the Western North Atlantic, Part 9

FIGURE 752. Rhechias dubia: ANSP 158290, 54 mm SL, Gulf of Mexico.

mm SL (ANSP 154677). Two early metamorphic specimens were 115 and 122 mm (ANSP 154709 and 154711). Identification. The leptocephalus of the closely related Uroconger lepturus was identified from Indian waters by Nair (1946) and Nair and Mohamed (1960). The present leptocephali are essentially identical and must, therefore, represent the Atlantic species, U. syringinus. Spawning and Growth. In the Gulf of Mexico, spawning seems to go on throughout the year. Specimens smaller than 20 mm SL were collected in each of the four seasons, and specimens collected at any one time and place often spanned nearly the entire size range. For this reason, growth rates cannot be determined. Distribution. From the Sargasso Sea, Bermuda, the Straits of Florida, and the Gulf of Mexico south through the Caribbean to the Guianas. Also the Gulf of Guinea.

154683 (3, 39-61), 154684 (1, 126), 154685 (69, 10-60), 154686 (5, 26-71), 154687 (6, 24-65), 154688 (3, 35-90), 154689 (5, 57-88), 154690 (6, 13-101), 154691 (1, 59), 154692 (7, 15-102), 154693 (2, 18-113), 154694 (1, 131), 154695 (10, 20-89), 154696 (1, 72), 154697 (7, 21-71), 154698 (1,62), 154700 (1,100), 154701 (2,101-102), 154702 (13, 28-66), 154703 (3, 42-80), 154704 (1, 96), 154705 (4, 28-84), 154706 (11, 40-72), 155824 (44, 7-20), 155825 (2, 15-18), 155826 (3, 16-18), 155827 (2, 40-67), 155828 (1, 30), 155829 (5, 21-39), 155830 (1, 47), 155831 (5,10-19), 155832 (11, 6-114), 155833 (5, 35-62), 155835 (3, 23-30), 155836 (1, 55), 155838 (1, 30), 155839 (2, 29-69), 155840 (1, 87), 155841 (1, 16), 155842 (1, 40), 155843 (1, 120), 155844 (2, 11-15), 155845 (7, 24-43), 155846 (3, 61-94), 155848 (1, 46), 155849 (10, 10-26), 155850 (7, 15-52), 155851 (1,35), 155852 (3,8-15), 155853 (4,24-36), 155854 (1, 43), 155855 (1, 48), 155856 (2, 64-70), 155857 (1, 34), 155858 (1, 41), 155859 (3, 17-30), 155860 (1, 62), 155861 (50, 9-28), 155862 (1, 35), 155863 (2, 28-54), 155864 (9, 24-48), 155865 (4,10-40), 156068 (3,25-115), 156069 (19, 47-108), 156070 (22, 53-107), 156071 (8, 13-117), 156072 (9, 18-118), 157618 (1, 85), 158285 (1, 20), 158286 (1, 93). MBI 233 (1, 76), 510 (13, 41-111).

Study Material. 621 specimens, 6-134 mm SL. SARGASSO SEA: ANSP 154712 (1, 72). BERMUDA: UMML Pillsbury 1049 (1, 101). BERMUDA-BAHAMAS: ANSP 154047 (1,124). BAHAMAS: ANSP 154043 (1, 84). UMML Tursiops 175 (1, 107). STRAITS OF FLORIDA: ANSP 154030 (1,91), 154034 (1,63), 154713 (1,64). UMML Gerda 100 (1,90), Oregon II7239-140 (1, 37). YUCATAN CHANNEL: ANSP 155834 (1, 66), 155837 (2, 25-40), 155847 (20, 7-14). HISPANIOLA: ANSP 154707 (2, 7478), 154708 (1, 94), 154709 (2, 115-117), 154710 (2, 48116). UMML Pillsbury 1268 (1, 82). COLOMBIA: ANSP 154045 (3, 97-121). GUIANAS: ANSP 154711 (1, 122). GULF OF MEXICO: ANSP 154657 (1, 80), 154658 (7, 959), 154659 (1, 87), 154660 (5, 22-118), 154661 (1, 127), 154662 (18, 33-100), 154663 (11, 27-112), 154664 (5, 4098), 154665 (1,70), 154666 (9,11-122), 154667 (3,10-114), 154668 (6,22-100), 154669 (5,33-75), 154670 (3, 37-112), 154671 (4, 46-112), 154672 (6, 46-99), 154673 (11, 19115), 154674 (5, 20-98), 154675 (5, 23-123), 154676 (1, 117), 154677 (4, 80-134), 154678 (13, 33-108), 154679 (2, 78), 154680 (1, 71), 154681 (1, 111), 154682 (2, 95-117),

Rhechias dubia (Breder, 1927) Figure 752 (?)Pseudoxenomystax dubius. Keller, 1976: 177. Pseudoxenomystax dubius. Smith, 1979: 30.

Distinctive Characters. Leptocephali of the Rhechias dubia complex resemble those of other Rhechias and Uroconger species in general form and pigmentation, but the tail is somewhat less acute. They have fewer myomeres than all the others except Rhechias thysanochila. Description. Total myomeres: ca 127-144 (n = 6), preanal myomeres 85-103 (7), predorsal myomeres 51-60 (4), LVBV 44-53 (6). Proportions as % of SL: preanal 81-89 (7), predorsal 57-59 (2), HL 8-11 (7), greatest depth 10-14 (7). Body moderate, deepest point at or slightly behind midlength, tail moderately acute. Gut long

Congrid Leptocephali and simple. Dorsal fin begins slightly behind midbody. Head moderately short. Pigmentation. A single row of moderately large melanophores along midlateral line from shortly behind head to tail, spaced about every one to three myomeres. A paired row of moderately small somatic melanophores along side of gut tube from shortly behind head to anus; larger specimens have a second row just above this on posterior two-thirds of gut. A few small melanophores lateral to heart and on upper jaw. A crescentic patch of pigment below eye. Very small melanophores on base of caudal fin and posterior anal-fin rays. Size. Maximum size unknown. The largest specimen examined was 54 mm SL (ANSP 155571), but it was not near metamorphosis. Identification. In overall form and pigmentation, this leptocephalus resembles those of Conger, Gnathophis, Rhynchoconger, and Uroconger. In possessing a moderately short head and a complete series of superficial midlateral melanophores, it seems especially close to Uroconger. By these criteria, the present leptocephalus could only belong to the Rhechias complex. Among these, the Rhechias dubia group is distinguished by its lower vertebral count and its somewhat less acute tail. Among the Rhechias-type leptocephali, the present form has relatively few myomeres, and its tail is somewhat less acute than that of other forms. In the Gulf of Mexico, Rhechias dubia has 138-145 vertebrae. The five specimens of the present leptocephali from the Gulf of Mexico have 140-144 myomeres. The only other species of Rhechias with 35 few vertebrae is R. thysanochila, but that species does not occur in the Gulf of Mexico; in addition, its tail is more acute. All the evidence points to Rhechias dubia as the species to which this leptocephalus belongs. In the Caribbean region, the populations of Rhechias dubia have 120-136 vertebrae. Two specimens were found that could belong to one of these: a 66-mm specimen from the Bahamas with approximately 137 myomeres (UMML ONR TOTO 11-3), and a 59-mm specimen from the Gulf Stream with about 127 myomeres (ANSP 154058).

753

Spawning and Growth. In the Gulf of Mexico a 21-mm specimen was collected in November (ANSP 155572). The remaining four specimens were collected in February and measured 20-54 mm SL. Spawning thus appears to be spread out over much of the fall and winter, but the sample is too small to provide more information than that. Remarks. Keller (1976: 177) tentatively identified 39 specimens from Bermuda as Pseudoxenomystax dubius, but some doubt remains. The total myomere count of 129-137 would fit the Caribbean forms of that species, but the preanal myomere count of 110-120 is greater than that of the specimens examined here. She further stated that the midlateral pigment began anywhere from the 22nd to the 100th myomere; in all the specimens examined here, and indeed in all Rhechias leptocephali seen so far, the midlateral melanophores are well developed and begin shortly behind the head. Distribution. The specimens were collected in the northwestern Gulf of Mexico, the Bahamas, and the Gulf Stream. Study Material Seven specimens, 21-66 mm SL. BAHAMAS: UMML ONR TOTO 11-3 (1,66), 24°34.4'N/ 77°21.3'W, 300 m, 20 June 1962. GULF STREAM: ANSP 154058 (1,59), 35°06'N, 74°47'W/ 307-372,5-6 Apr. 1967. GULF OF MEXICO: ANSP 154235 (1, 20) and 158290 (1, 54), 27°46.3'N, 94°18.5'W, 300 mwo, 1 Mar. 1977. 155571 (1,52), 26°37.4'N, 96"03.3'W, 30-37 m, 27 Feb. 1977.155572 (1, 21), 27°23.5'N, 94°19.8'W, 180-195 m, 19 Nov. 1975. 155573 (1, 32), 27°27.7'N, 95°34.2'W, 15-95 m, 28 Feb. 1977. Rhechias thysanochila (Reid, 1934) Leptocephalus type 1. Keller, 1976: 178.

Distinctive Characters. Like all species of the Rhechias group, this leptocephalus has a complete series of midlateral melanophores, a relatively short head, and suborbital pigment. It has about the same number of total myomeres as the northern population of Rhechias dubia but slightly more preanal myomeres (105-109 vs 85-103) and predorsal myomeres (64-67 vs 51-60). It also has a more acute tail, and it is not found in the Gulf of Mexico. The populations of R. dubia that are found in the Caribbean have fewer myomeres.

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Fishes of the Western North Atlantic, Part 9

All other known leptocephali of the Rhechias group have more myomeres. Description. Total myomeres 142-146 (n = 5), preanal myomeres 105-109 (5), predorsal myomeres 64-67 (4), LVBV 49-50 (2). Proportions as % of SL: preanal 89-92 (5), predorsal 65-67 (2), HL 6-7 (5), greatest depth 12-14 (5). Body moderately elongate, deepest point at or slightly behind midlength, tail acute. Gut long and simple, anus at about nine-tenths SL. Dorsal fin begins at about two-thirds SL. Head and snout short. Pigmentation. A series of moderately large melanophores along midlateral line, spaced every one to three myomeres. A paired row of moderately large somatic melanophores along top of gut tube from shortly behind head to anus. One or two melanophores lateral to heart. A crescentic patch of pigment below eye. Size. The largest specimen examined was 88 mm SL (UMML Pillsbury 1236). Keller's (1976: 217) largest specimen was 108 mm and still premetamorphic. Identification. Aside from Rhechias dubia Population I, R. thysanochila is the only species of Rhechias whose vertebral count (142-149) matches the myomere count of the present leptocephalus. Adults of R. thysanochila occur in the Caribbean, where the present leptocephali were collected. Distribution. Jamaica, Hispaniola, and the Bahamas. Study Material 5 specimens, 48-88 mm SL. BAHAMAS: ANSP 154028 (1, 47), 26°19'N, 78*41'W, 150 m, 27 Apr. 1966. ANSP 154053 (1, 86), 26°28.4'N, 78°41.3'W, ca 76 m, 1 Aug. 1965. JAMAICA: UMML Pillsbury 1236 (1, 88), 18°04'N, 78°34.5'W, 0-400 m, 7-8 July 1970. HISPANIOLA: UMML Pillsbury 1179 (2, 61-78), 19°01.5'N, 73°35'W, 80-130 m, 30 June 1970.

tions as % of SL: preanal 83-97 (14), predorsal ca 73-77 (2), HL 6-10 (14), greatest depth 10-15 (14). Otherwise identical to Rhechias thysanochila. Size. The largest specimen examined was 86 mm SL (ANSP 154049). Identification. Rhechias vicinalis has 168-176 vertebrae and is widely distributed from the eastern Gulf of Mexico to the mouth of the Amazon. There is no specific evidence to link it to the present leptocephalus, however. Of the other known species of Rhechias, R. bullisi has more vertebrae (179-186), and the vertebral count of R. polypora is unknown. Spawning and Growth. Specimens smaller than 20 mm SL were present in the fall, winter, and spring, indicating an extended spawning season. Remarks. Seven small specimens (13-39 mm SL) from the Yucatan Channel (see study material) were assigned to this species although total myomere counts were unavailable. Their consistency in other characters, especially LVBV myomeres, indicated that they were probably all the same species. Distribution. Virgin Islands, Puerto Rico Deep, Yucatan Channel, eastern Gulf of Mexico, and Bermuda. Study Material. 13 specimens, 13-86 mm SL. YUCATAN CHANNEL: ANSP 154233 (1, 57), 20°32.1'N, 87°00.0'W, 75 m, 12 Apr. 1976. 155579 (1, 23), 21°36.0'N, 85°57.7'W, 900 mwo, 15 Feb. 1977. 155581 (1, 16), 20°36'N, 87°00'W, 35-45 m, 8 Nov. 1975. 155582 (2, 13-24), 20°42.3'N, 86°53.9'W, 65-70 m, 13 Feb. 1977.155583 (2,15-28), 20°30.7'N, 87°00.3'W, 75-80, 11-12 Apr. 1976. 155584 (1, 39), 18°45'N, 87°30'W, 55 m, 23 July 1977. PUERTO RICO: ANSP 154046 (1, 44), 20°02'N, 65°01'W, ca 50 m, 4 July 1971. 154049 (2,75-86), 20°03'N, 64°57'W, 50 m, 3-4 July 1971. VIRGIN ISLANDS: ANSP 154042 (2, 55-60), 17°57.9'N, 65°04.9'W, 50 m, 12 July 1971.

Rhechias species B Rhechias species A Leptoceophalus type 5a*. Keller, 1976: 177.

Distinctive Characters. Total myomeres 165-170, LVBV 51-57. Description. Total myomeres ca 165-170 (n = 7), preanal myomeres 99-140 (12), predorsal myomeres 92-100 (3), LVBV 51-57 (14). Propor-

Distinctive Characters. Total myomeres ca 173177, LVBV 60-64. Description. Total myomeres ca 173-177 (n = 5), preanal myomeres 148-156 (5), predorsal myomeres ca 75-104 (4), LVBV 60-64 (5). Proportions as % of SL: preanal 93-95 (5), HL 6-7 (5), greatest depth 10-12 (5). Otherwise identical to Rhechias thysanochila,

Congrid Leptocephali except that one specimen has some extra pigment above and below the midlateral line (ANSP 155580). Size. The largest specimen examined was 79 mm SL (ANSP 154232). Identification. This leptocephalus seems to be restricted to the western Gulf of Mexico. No species of Rhechias is known to be similarly restricted, so an identification cannot be made. Rhechias vicinalis has a vertebral count similar to the myomere count of the leptocephali, but R. vicinalis is widespread in the western Atlantic. Rhechias bullisi occurs in the western Gulf of Mexico, but it has more vertebrae (179-186). It should be noted, however, that most of the vertebral counts obtained for R. bullisi were made on specimens from the Caribbean. Several other eels show differentiation in vertebral number between the Gulf of Mexico and the Caribbean. If Rhechias bullisi has similarly differentiated, and if the Gulf population has fewer vertebrae than the Caribbean one, then these leptocephali could be R. bullisi. This scenario, however, remains pure speculation. Spawning and Growth. The single winter specimen (ANSP 155580) was smaller (44 mm SL) than the four spring specimens (57-79 mm). This suggests that spawning takes place in the fall, but the sample is too small to permit much analysis. Distribution. Western Gulf of Mexico. Study Material. Five specimens, 44-79 mm SL. GULF OF MEXICO: ANSP 154232 (3,57-79), 22°29.4'N, 95°04.9'W, 150 mwo, 19 Apr. 1976. 155578 (1, 57), 22°29.6'N, 95°07.0'W/ 150 mwo, 19 Apr. 1976. 155580 (1, 44), 23°02.8'/ 90°57.2'W, 22-27 m, 17 Feb. 1977. Rhechias species C Congrina sp. Castle, 1970a: 5, fig. 2. Keller, 1976: 181.

Distinctive Characters. Three rows of lateral melanophores, 158-168 myomeres. Description. Total myomeres: 158-168 (n = 5), preanal myomeres 140 (1), LVBV 55 (1). Pigmentation. Three rows of moderately large melanophores on side of body: one on midlateral line, one above it and one below it. A paired

755

series of melanophores along gut from throat to anus. A few melanophores on dorsal midline just behind head. A crescentic patch of pigment below eye. Size. This is a large leptocephalus, reaching at least 168 mm SL (Castle, 1970a: 5). Identification. Castle (1968c: 710; 1969a: 2) discovered that juveniles of Congrina (= Rhechias) species from the Indo-Pacific retain a larval pigmentation pattern of three longitudinal rows of small melanophores on the flank. From this he was able to identify two previously described leptocephali (Leptocephalus trilineatus Castle, 1964, and L. geminus Castle, 1964) as leptocephali of Rhechias. When he found a similar leptocephalus in the tropical South Atlantic, he referred it to the same genus. Juveniles of all Rhechias species examined from the Atlantic, however, show a single row of lateral melanophores. Although this supports the identification of the leptocephali discussed above, it leaves the three-rowed Atlantic leptocephali without a known adult. The best guess at this point is that the threerowed leptocephali represent a distinct group of species within Rhechias and that this group is found predominantly in the Indo-West Pacific. At least one species, however, occurs in the Atlantic, as evidenced by the present leptocephalus. Remarks. There is some uncertainty about the consistency of the extra midlateral pigment. In his descriptions of the Indo-Pacific Leptocephalus trilineatus and L. geminus, Castle (1964b: 32-33) noted that the melanophores in the supra- and sublateral rows were fewer and more irregularly spaced than those of the midlateral row. It was mentioned above that one specimen of Rhechias sp. B examined here had some extra pigment above and below the midlateral series, although it differed in no other way from the other specimens. All the specimens recorded here as Rhechias species C are very large (115-168 mm SL), much larger than specimens of the other species of Rhechias. The possibility cannot entirely be excluded that these specimens are simply examples of Rhechias sp. A that display extra lateral pigment, and that this extra pigment tends to develop at larger sizes. An analogy is found in

Fishes of the Western North Atlantic, Part 9

756

Conger oceanicus, which develops lateral pigment as it grows. Distribution. Castle's specimen was taken off Brazil at about 1()°S. Keller's were from Bermuda. Study Material None.

ADDITIONAL NOTES ON RHECHIAS SPECIES Numerous specimens were examined which, although clearly belonging to the Rhechias group, could not be assigned to any of the species described above. In many cases, this was because critical characters were not available. Accurate myomere counts are particularly difficult to obtain in this group because of the attenuate tail, especially in small specimens. The last vertical blood vessel is also sometimes difficult to see. These meristic features are about the only diagnostic characters, and without them specimens cannot be allocated. A few specimens, nevertheless, seemed to be distinct. Two specimens from the eastern Gulf of Mexico (UMML Oregon II 7020, stations 1-17-2 and 2-17-3) had about 172-179 total myomeres and 46 LVB V myomeres. The former counts are close to the values found in Rhechias sp. B, which occurs in the Gulf of Mexico, but the latter are much too low. Several specimens seem to have between 180 and 190 myomeres, but the counts are only very approximate. No leptocephali were found that could unambiguously be attributed to Rhechias bullisi, a species that does not seem to be particularly rare. Its distinctive vertebral count (179-186) should make its leptocephali easy to recognize, but no such leptocephali were found. (?)Bathyuroconger vicinus (Vaillant, 1888) Bathyuroconger vicinus. Blache, 1977: 141, figs. 46a, 47.

Distinctive Characters. Three rows of lateral melanophores, total myomeres 176-187. Description. Total myomeres 176-187 (n = 6), LVBV 59-64 (6). Proportions as % of TL: preanal 94-95 (5), predorsal 59-66 (5).

Form and proportions of body, head, gut, and fins as in Rhechias spp. Pigmentation. A series of moderately large melanophores along midlateral line, spaced about one per myomere. A slightly more irregular and widely spaced row of melanophores above and below this. A paired series of moderately large, closely spaced melanophores along top of gut from shortly behind head to anus. A few melanophores lateral to heart. A crescentic patch of pigment beneath eye. Size. Maximum size at least 206 mm TL (Blache, 1977: 141). Identification. Juveniles of Bathyuroconger vicinus have two irregular longitudinal series of small melanophores above and below the lateral line. Along with a series of small melanophores on the ventral midline, these seem to be remnants of larval pigment. Bathyuroconger vicinus has 179186 vertebrae. The identification seems logical, but some questions remain. These leptocephali are essentially identical to the three-rowed Rhechias leptocephali discussed above. Blache (1977: 145) used this similarity to suggest that the Indo-Pacific species of Rhechias should be transferred to Bathyuroconger. A cursory examination of the adults, however, shows that they resemble the Atlantic species of Rhechias much more than they do Bathyuroconger vicinus. If the present leptocephali are B. vicinus, then the pattern of pigmentation must either be convergent with that of Rhechias or primitive and retained from a common ancestor. Another discrepancy is the rarity of the leptocephali compared to the adults. Bathyuroconger vicinus is commonly collected on both sides of the Atlantic. Only six specimens of the present leptocephali are known, however, all from the Gulf of Guinea. These leptocephali may indeed belong to Bathyuroconger vicinus, but until metamorphic specimens are found, the identification will have to be tentative. Distribution. Gulf of Guinea. Study Material. None.

Congrid Leptocephali

757

FIGURE 753. Pseudophichthys splendens (B-D from Smith, 1979: fig. 45): A. ANSP 155906, 19 mm SL, Gulf of Mexico. B. ANSP 154652, 50 mm SL, Gulf of Mexico. C. Same; head. D. Same; tail.

Pseudophichthys splendens (Lea, 1913) Figure 753 Unnamed. Murray and Hjort, 1912b: fig. 80. Leptocephalus splendens Lea, 1913: 29, fig. 19, pi. 4, fig. 2. Leptocephalus sp. Roule, 1914b: 7. Leptocephalus species E. Roule, 1919: 104, pi. 7, fig. 5-5b. Pseudophichthys splendens. Smith, 1971: 79; 1979: 30, fig. 45. Keller, 1976: 179.

Distinctive Characters. This leptocephalus is easily recognized by the distinctive pattern of pigmentation. Description (including data from Lea, 1913, and Keller, 1976). Total myomeres 131-137 (n = 28), preanal myomeres 79-84 (8), predorsal myomeres 83-85 (2), LVBV 56-59 (3). Proportions as % of SL: preanal 72-83 (7), predorsal 83-85 (2), HL 7-12 (6), greatest depth 11-16 (5). Body moderate, deepest point somewhat behind midlength, tail moderately acute. Gut nar-

row, moderately long, anus at about three-quarters SL; in larger specimens posterior half of gut shows several low undulations or loops. Dorsal fin relatively short, begins slightly behind level of anus. Head and snout moderate in length, wedge-shaped in profile. Pigmentation. Lateral pigment complex and scattered over entire surface of body. Four conspicuous clusters of small melanophores located slightly below midlateral line, generally centered on one myomere and drawn out slightly in a vertical direction along that myomere. Remaining lateral pigment generally consists of single melanophores, moderate to small in size, scattered above, on, and below midlateral line, but some of these spots are aggregates of two or more melanophores. Usually an especially conspicuous melanophore or cluster of melanophores just above midlateral line between anus and tip of

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A

FIGURE 754. Acromycter: A. URI Ocean Acre 9-5, 170 mm SL, Bermuda (adapted from Smith and Leiby, 1980:fig.2A). B. ANSP 155894, 17 mm SL, Gulf of Mexico.

tail. Moderately large melanophores distributed somewhat irregularly along ventral margin, located ventral, lateral, and dorsal to gut tube. One or two melanophores lateral to heart. Size. Keller (1976: fig. 30) recorded specimens up to almost 120 mm SL, all premetamorphic. Identification. The unique pigmentation is retained in juveniles (see family Congridae, fig. 583). Spawning and Growth. Specimens are collected throughout the year, and there seems to be no special spawning season. Distribution. Caribbean, Gulf of Mexico, Straits of Florida, Bermuda, Sargasso Sea, off northwestern Africa. Blache (1977) did not record leptocephali from the Gulf of Guinea, although adults occur there. All the evidence indicates that this species lives at greater depths than most other congrid leptocephali. Keller (1976: 222) observed that in the Ocean Acre, near Bermuda, specimens were collected at 138-298 m in discrete-depth tows made at night; most other leptocephali were caught in the upper 100 m. During the MBI cruises, this species was collected in open tows with 300 and 600 m of wire out, although most tows were made with 150 or fewer m of wire. Study Material 12 specimens, 17-107 mm SL. SARGASSO SEA: ISH Anton Dohrn 5628IK-13 (1,107), 23°31'N/ 57°20'W, 185 m, 31 Mar. 1979. 5674 IK-21 (1, 90+), 25°09'N/ 58°07'W, 100 m, 4 Apr. 1979. STRAITS OF FLORIDA: ANSP 154654 (1, 41), 24°57'N/ 79°57'W, 208259 m, 8-9 Mar. 1963. 154655 (1, 17), 25°32'N/ 80°03'W, 154 m, 20 Dec. 1962. YUCATAN CHANNEL: ANSP 155060 (1, 55), 18°45'N, 87°30'W/150-230 m, 23 July 1977. GULF OF MEXICO: ANSP 108837 (2, 80-98), 27°40'N,

90°50'W, 183-229 m, 24 Aug. 1960. 154652 (1, 50), 22°29.2'N, 95°09.7'W, 600 mwo, 19 Apr. 1976. 154653 (1, 63), 20°00.0'N, 94°39.3'W, 2000 mwo, 16 Apr. 1976.155906 (1, 19), 27°20.3'N, 95°31.0'W, 95-160 m, 28 Feb. 1977. HISPANIOLA: UMML 28148 (1, 95), 20°09.5', 71°30'W, 0-458 m, 13 Oct. 1963. COLOMBIA: ANSP 154656 (1, 84), 9°55.5'N, 76°20.0'W, 240-250 m, 16 July 1966.

Acromycter species Figure 754 Acromycter alcocki(not of Gilbert and Cramer, 1897). Smith and Leiby, 1980.

Distinctive Characters. Elongate body; ten loops in gut, each capped by a pigment spot; three additional spots behind anus, two below midlateral line and one above it. Two liver lobes. Superficially, this leptocephalus resembles an ophichthid, but it differs in several characters. The gut does not expand abruptly between the esophagus and intestine, as it does in ophichthids. In Acromycter the gall bladder is largely hidden by the liver, and the kidney terminates about 50 myomeres before the anus. In ophichthid leptocephali, by contrast, the gall bladder is exposed to view, and the kidney terminates within 15 myomeres of the anus. In Acromycter the pigment capping the gut loops lies dorsal to the kidney, whereas in ophichthids it lies mainly below the kidney on the dorsal surface of the gut. The postanal pigment spots in Acromycter are large and superficial. Postanal spots in ophichthids are either small and superficial or large and deep, but never large and superficial. Description. Total myomeres 163-172 (n = 7), preanal myomeres 100-104 (7), predorsal myo-

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Congrid Leptocephali

meres 116-117 (2), nephric myomeres 51-54 (7). Gut loops at myomeres 13-16 (9), 21-26 (9), 3943 (9), 50-54 (8), 59-64 (8), 67-74 (8), 77-85 (8), 86-94 (8), 96-104 (8). Postanal pigment spots at myomeres 109-113 (6), 122-129 (6), 138-148 (6). Proportions as % of SL: preanal 70-83 (6), predorsal 80 (1), HL 3-9 (7), greatest depth 5-10 (6). Body elongate, depth rather uniform, tail moderately acute. Gut narrow, with ten distinct loops, anus at about three-quarters SL; two liver lobes. Dorsal fin relatively short, begins approximately 10-15 myomeres behind level of anus. Head and snout moderate. Pigmentation. Each gut loop capped apically by a conspicuous pigment spot, consisting of one to several melanophores internally and externally, sometimes extending dorsally almost to aorta. Three conspicuous pigment spots postanally, the first two between midlateral line and ventral edge of myomeres, and the last just above notochord. Size. The largest specimen examined was 183 mm SL, premetamorphic (URIZ Ocean Acre 1235 B). Two metamorphic specimens were 146 and 158 mm (URIZ Ocean Acre 7-13, ANSP 143371). Identification. Smith and Leiby (1980) identified this leptocephalus through metamorphosing specimens and a juvenile that had retained the larval pigment. The two species of Acromycter in the western North Atlantic differ primarily in their vertebral number, 159-162 in A. perturbator and 167-171 in A. atlanticus. Based on this character, most of the specimens examined here belong to A. atlanticus. One specimen with approximately 163 myomeres (ANSP 154815) may be A. perturbator. Spawning and Growth. The smallest specimen, 17 mm SL (ANSP 155894), was collected in February. Metamorphic specimens were collected in March and September. Spawning probably takes place year-round. Growth rate and duration of larval life cannot be estimated from the material at hand. Distribution. The specimens examined came from the Gulf of Mexico, the Straits of Florida, the Bahamas, Bermuda, and the Sargasso Sea. Study Material. Nine specimens, 17-183 mm SL. SARGASSO SEA: ANSP 143371 (1, 158), 25°31'N/ 62°00'W, 0-1800 m, 6 Apr. 1979. BERMUDA: URIZ Ocean

Acre 7-13 (1,146 metamorphic), 32°18'N/ 63°30'W, 0-1500 m, 8 Sept. 1969. 9-5 (1, 170), 31°54'N, 64°17'W, 0-140 m, 17 Mar. 1969. 12-35 B (1, ca 183), 32°28'N, 64°02'W, 7 Sept. 1981. 14-9 A (1, 87), 31°46'N, 63°38'W, 7 June 1972. BAHAMAS: ANSP 154815 (1, 72), Columbus Iselin 257 (data unavailable). UMML Gerda 497 (1, 34), 26°41'N, 79°00'W, 0-18 m, 3 Feb. 1965. STRAITS OF FLORIDA: UMML Gerda 92 (1, 60), 25°10'N, 79°41'W, 0-157 m, 19 Apr. 1963. GULF OF MEXICO: ANSP 155894 (1, 17), 20'28.5'N, 96°05.5'W, 0-67 m, 24 Feb. 1977.

Xenomystax congroides

Smith and Kanazawa, 1989 Figure 755, 756 Paraxenomystax bidentatus (not of Reid, 1940). Blache, 1968a: 717, figs. 19-24; 1977: 159, figs. 52a, 53-54. Castle, 1970a: 13. Karmovskaya, 1975: 95. Keller, 1976:132. Paraxenomystax sp. Fahay, 1976: 210, fig. 1. Smith, 1979: 31, fig. 47.

Distinctive Characters. This leptocephalus is distinguished by its large, expanded lateral melanophores, and the form of its body, which deepens abruptly behind the head. Description (including data from Castle, 1970a; Fahay, 1976; Keller, 1976; Blache, 1977). Total myomeres ca 189-221 (n = 182), preanal myomeres ca 120-148 (32), predorsal myomeres 99101 (3), LVBV 52-67 (48). Proportions as % of SL: preanal 85-91 (27), predorsal ca 71-72 (2), HL 59 (25), greatest depth 9-15 (22). Body moderately elongate, deepest point just behind head, tapering toward tail; tail acute; the deepening of body behind head becomes more abrupt in large specimens. Gut long and simple, anus at about nine-tenths SL. Dorsal fin begins a short distance before anus at about three-quarters SL. Head and snout moderate, with a rounded profile in larger specimens. Pigmentation. Several large, expanded melanophores distributed irregularly on either side of body just below midlateral line. Sometimes a few additional melanophores anteriorly below midlateral series and just above ventral margin of myomeres. A few moderately large melanophores on anterior part of gut, sometimes additional melanophores on middle and posterior part of gut as well. A few melanophores lateral to heart. Pigment on head behind brain and on rostrum.

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Fishes of the Western North Atlantic, Part 9

A

FIGURE 755. Xenomystax congroides: ANSP 155918, 113 mm SL, Gulf of Mexico (B, C from Smith, 1979: fig. 47). A. Whole view. B. Same; head. C. Same; tail.

Size. The largest specimen known is 350 mm TL, reported by Castle (1970a: 13). Blache (1977: 164) recorded two metamorphic specimens 228 and 235 mm TL. A 183-mm specimen examined here was metamorphosing (ANSP 154650). Variation. This species is divided into four distinct populations: one in the Gulf of Mexico, one in the Caribbean and Bahamas, one off the Guianas and Brazil, and one off West Africa (see p. 565). The myomere counts of the leptocephali generally follow the pattern of vertebral counts found in the adults. Thus, leptocephali from the Gulf of Mexico have 189-196 myomeres, those from the Caribbean have about 200-212, and those from the Gulf of Guinea have 213-219 (Blache, 1977: 159). A few discrepancies appear in the literature. Castle (1970a: 13) recorded a count of 195 from the equatorial Atlantic, and Keller (1976:132) recorded counts as high as 221 from Bermuda. In addition to myomere counts, the pigmentation also varies between populations. Specimens from the Gulf of Mexico generally have one ventral melanophore near the anterior end of the gut and another near the posterior end. Specimens from the Caribbean have more ventral melanophores, sometimes extending along

the entire length of the gut. Blache (1977: 161, fig. 53d) showed several additional melanophores on the lower side of the body anteriorly in a 225-mm specimen from the Gulf of Guinea. Castle (1970a: 13) described a similar pattern in specimens from the central equatorial Atlantic, but such accessory lateral pigment has not been observed in specimens from the Caribbean and Gulf of Mexico. The number of LVBV myomeres also seems to vary. In specimens from the western Atlantic examined here, the value was 52-56. Blache (1977: 159) recorded 63-67 in specimens from the Gulf of Guinea, and the single value given by Castle (1970a: 13) for the central equatorial Atlantic was 65. Identification. Blache (1968a: 718) identified this leptocephalus from metamorphosing specimens. Spawning and Growth. In the Gulf of Mexico average size increases from fall to summer (Fig. 756), yet the wide range of sizes, particularly in the spring collection, suggests that the spawning period is extended, probably at least through the fall and winter. The absence of large specimens in the fall suggests that development is completed within a year. The small size of the sample requires caution, however. In addition, speci-

Congrid Leptocephali mens at the upper end of the growth scale may be too large to be sampled effectively with the 2-meter net. In the Sargasso Sea, more specimens were taken with the large midwater trawl (27, 91-236 mm SL) than with the 3-m Isaacs-Kid Midwater Trawl (5, 155-179 mm SL). Distribution. This leptocephalus occurs over much of the tropical Atlantic from the Gulf of Guinea and Brazil to the Caribbean, the Gulf of Mexico, the Straits of Florida, Bermuda, the Sargasso Sea, and the central Atlantic. This in part reflects the wide distribution of the adult, but the leptocephalus itself seems to be long-lived and is carried considerable distances on the currents. The wide discrepancy in size between the largest premetamorphic specimens and the known metamorphic ones suggests that metamorphosis can be delayed if the leptocephalus does not find itself in a favorable area. Study Material. 78 specimens, 9-236 mm SL. SARGASSO SEA: ISH Anton Dohrn5550MT-3 (7,153195), 5560 MT-4 (1, 191), 5561 MT-5 (3, 135-170), 5576 IK-5 (1, 179), 5588 IK-6 (1,173), 5588 MT-6 (1, 184), 5596 MT-8 (8,137-185), 5632 MT-11 (5,140-212), 5641 MT-12 (1,162), 5653IK-17 (1,161), 5674IK-21 (1,159), 5698IK27 (1,155), 5688 MOC 14-3 (1,141), 5760 MT-21 (1, 236). BAHAMAS: ANSP 154643 (1, 119). STRAITS OF FLORIDA: ANSP 154627 (3, 57-68), 154651 (1,120), 158280 (1, 50), 158281 (2, 105-116). EASTERN GULF OF MEXICO: ANSP 155645 (1, 43). WESTERN GULF OF MEXICO: ANSP 154620 (2, 84-85), 154621 (4, 31-83), 154622 (1, 57), 154623 (2,48-69), 154624 (4, 64-73), 154625 (1, 81), 155558 (1,128), 155559 (1, 53), 155560 (1, 61), 155561 (1, 37), 155562 (1,54), 155563 (1, 38), 155565 (1,113), 155566 (4, 36-41), 155567 (1, 24), 155568 (1, 71), 155569 (1, 44), 155570 (1, 9), 155918 (1, 113). MBI 205 (1, 102), 334 (1, 57). YUCATAN CHANNEL: ANSP 155564 (1, 60). HISPANIOLA: ANSP 154639 (1, 129), 154650 (1, 183). COLOMBIA: ANSP 154636 (1, 126).

Xenomystax bidentatus (Reid, 1940) Distinctive Characters. Identical to Xenomystax congroides but total myomeres ca 175. Description. Total myomeres ca 175 (n = 1), preanal myomeres ca 136 (1), LVBV 56 (1). Proportions as % of SL: preanal 92 (1), HL 9 (1), greatest depth 11 (1). Otherwise identical to Xenomystax congroides. Size. The specimen is 79 mm SL.

4 3 21-

761

Foil

Winrer

I

I I

Spring

4 3 2 1-

Summer

I 50mm

100mm

SL

FIGURE 756. Size distribution of leptocephali of Xenomystax congroides in the Gulf of Mexico over four seasons.

Identification. The two other species of Xenomystax known from the western Atlantic are X. bidentatus, which has 175-180 vertebrae, and X. austrinus, which has 192-196. By this criterion, the present leptocephalus would be X. bidentatus. Distribution. The single specimen came from the Straits of Florida about midway between Key Largo and the Great Bahama Bank. Study Material. One specimen, 79 mm SL. STRAITS OF FLORIDA: ANSP 158279 (1, 79), 25°21'N, 79°50'W/ 50 m, 9 May 1963.

CONGRID AE Genus B species A Figure 757 Distinctive Characters. Small melanophores scattered over lateral surface of body; 114-116 myomeres. Description. Total myomeres 114-116 (n = 4), preanal myomeres 93-97 (4), predorsal myomeres 54-57 (3), LVBV 53-56 (4). Proportions as % of SL: preanal 90-92 (3), predorsal 55-59 (3), HL 8-10 (3), greatest depth 16-21 (3). Body moderately deep, deepest point about midlength; tail moderate. Gut simple, rather long,

762

Fishes of the Western North Atlantic, Part 9

FIGURE 757. Congridae, Genus B species A: ZMUC Dana 1314 VI, 61 mm SL, Virgin Islands.

anus at about nine-tenths SL. Dorsal fin begins slightly behind midbody. Head and snout moderately short. Pigmentation. Moderately small melanophores scattered over lateral surface of body; in illustrated specimen (ZMUC Dana 1314 VI), these melanophores occur above and below midlateral line, but in other specimens they are concentrated on ventral half of body. A series of moderately small melanophores on underside of esophagus, switching to top of intestine behind gastric region and becoming somewhat more irregular posteriorly; a concentration of melanophores on lateral surface of gut just before anus. Size. The largest specimen examined was 74 mm SL (ZMUC Dana 1314 V). Identification. This leptocephalus is assumed to be a congrid because of its relatively long, simple gut and ventral pigment. The myomere count is unusually low. There is no known adult eel with which it can be matched. Distribution. The specimens were all taken just west of St. Croix, Virgin Islands. Study Material. Four specimens, 36-74 mm SL. VIRGIN ISLANDS: ZMUCDana 1279 V (1,36), 17°43'N, 64°56'W, 100 mwo, 30 Mar. 1922. 1314 II (1, 49), same position, 800 mwo, 22 Apr. 1922. 1314 V (1, 74), same, 100 mwo. 1314 VI (1, 61), same, 50 mwo.

CONGRIDAE Genus C species A Distinctive Characters. Long, slender body; long gut; large, expanded melanophores on side of body. Ca 172-176 myomeres. Description. Total myomeres ca 172-176 (n = 4), preanal myomeres 122-123 (3), predorsal myomeres 87-89 (3), LVBV 51 (1). Proportions as

% of SL: preanal 88-90 (3), predorsal 72 (1), HL 7 (1), greatest depth 8 (1). Body elongate, relatively uniform in depth, tail acute. Gut long and simple, anus near nine-tenths SL. Dorsal fin begins near last quarter of SL. Head and snout relatively elongate, dorsal profile straight or slightly convex. Pigmentation. All four specimens have five large, expanded melanophores along the midlateral line, distributed unequally on the two sides; three specimens have two on the right and three on the left, one specimen has three on the right and two on the left. One or two large melanophores on gut near anterior end. Size. The largest specimen is 95 mm SL (MCZ 64868) and is beginning to metamorphose. Identification. In the overall form of the head and body, this leptocephalus strongly resembles that of the Indo-Pacific Gavialiceps taeniola (Castle, 1977a), a species closely related to Xenomystax. The main difference is that G. taeniola lacks lateral pigment. The lateral pigment of the present leptocephalus is very similar to that found in leptocephali of Xenomystax congroides. Taken together, these characters suggest that this leptocephalus belongs to the Xenomystax group. The myomere counts of the specimens fall within the range of vertebral counts of Xenomystax bidentatus (175-180), but a typical Xenomystax-like leptocephalus with 175 myomeres is already known (see Xenomystax bidentatus above). At this point, the leptocephalus cannot be identified. Remarks. One specimen (MCZ 64868, 95 mm SL) is just beginning the process of metamorphosis. The anus has begun to move forward, the dorsal and anal fins are larger and better

Congrid Leptocephali

763

FIGURE 758. Congridae, Genus C species B: ANSP 158295, 137 mm SL, Hispaniola. A. Whole view. B. Head.

developed than in the other specimens, and the tail is beginning to assume a more attenuate and definitive form. The low preanal myomere count of 104 reflects this process. Distribution. The specimens were taken in the northwestern and southwestern Caribbean. Study Material. Four specimens, 80-95 mm SL. HISPANIOLA: ANSP 156734 (1, 94), 18°14.8'N, 69°15.2'W/ ca 80 m, 10 July 1971. NORTHEASTERN CARIBBEAN: MCZ 64869 (2,80-84), 16°38'N, 64°27'W/110133 m, 25 May 1966. SOUTHWESTERN CARIBBEAN: MCZ 64868 (1, 95), 13°07'N, 78°23'W/100-109 m, 5 June 1966.

CONGRIDAE Genus C species B Figure 758 Distinctive Characters. Identical to Genus C species A, but more myomeres and more lateral melanophores. Description. Total myomeres ca 193 (1), preanal myomeres 145 (1), predorsal myomeres 102 (1), LVBV 62 (1). Otherwise identical to Genus C species A. Pigmentation. Ten lateral melanophores, two on left and eight on right. Remarks. Though superficially identical to the four specimens described above, this one has significantly more myomeres and more lateral melanophores. It is also distinctly larger than any

of the four specimens of species A. One of the latter is beginning to metamorphose at 95 mm SL; the present specimen is 137 mm SL and shows no sign of metamorphosis. Distribution. The specimen was collected off the south coast of the Dominican Republic at the same station as species A, ANSP 156734. Study Material. One specimen, 137 mm SL. HISPANIOLA: ANSP 158295, Pillsbury 1391,18°14.8'N, 69°15.2'W, ca 80 m, 10 July 1971.

NOTES ON GENUS C Approximately 100 specimens of Genus C were found in the Dana collections at the ZMUC. These came from 35 separate stations made during March and April of 1922 around Puerto Rico, the Virgin Islands, and Guadaloupe. Counts and measurements were not made, so the specimens cannot be assigned to either species A or species B. PUERTO RICO: ZMUC Dana 1260 IV (2). VIRGIN ISLANDS: ZMUC Dana. 1253 III (many), 1256 I (1), 1256 IV (many), 1257 II (3), 1257 IV (8), 1261 IV (1), 1266 II (1), 1266 V (6), 1268 III (1), 1269 X (1), 1272 II (1), 1273 VII (1), 1273 IX (3), 1274 IV (5), 1276 I (1), 1276 II (1), 1276 IV (3), 1278 IV (3), 1279 III (1), 1279 IV (3), 1281 III (1), 1281IV (2), 1289 IV (3), 1289 X (1), 1291IV (1), 1292 IV (1), 1293 IV (2), 1294 IV (2), 1296 III (1), 1296 IV (1), 1314 III (1). LESSER ANTILLES: Dana 1287 V, 1286 IV.

Family Ophichthidae: Leptocephali MARK M. LEIBY The engyodontic stage commences at hatching. It is characterized by: the presence of yolk in its youngest members; a few needle-like teeth, each shorter than the one anterior to it; lower jaw equal to or longer than the upper jaw; nasal capsule unformed or visible only as a slight depression in the snout; median fin-fold diaphanous, not yet differentiating; hypurals not yet forming; notochord not yet flexed; ratios of head and preanal lengths to total length high as compared to other stages (Figs. 759, 760). Euryodontic stage (Figs. 759,760,782C-E, 794CE): The term euryodontic is derived from the greek words eurys meaning broad and odon meaning tooth to describe the broad-based teeth present in the larvae of this stage. This stage commences with the shedding or resorption of the needle-like engyodontic teeth. Concurrent with the loss of the engyodontic teeth, three series of broad-based euryodontic teeth are formed in the mesenchyme and overlay, but do not touch, the maxilla and dentary. During development each tooth lies parallel to the jaw. When fully formed, the tooth rotates until it is perpendicular to the jaw. The broad base of the tooth then migrates inward, becoming ankylosed to the outer surface of the jaw bone. The upper jaw becomes longer than the lower, ratios of head and preanal length to total length decrease (Figs. 759, 760), the nasal capsule develops but nostrils are not yet differentiated, the notochord flexes, and hypural formation and median fin differentiation begin. Metamorphic stage (Figs. 759, 760, 782F, 794F,G,I): During this stage the anterior and posterior nostrils form, with the anterior nostril becoming tubular; the epidermis thickens; the body becomes thicker, more tubular, its length and

Acknowledgements. I thank the following people for generously sharing their knowledge of eels and eel larvae, for permission to examine specimens and X-rays in their care, and for the loan or donation of adult and larval specimens: T. C Hopkins and D. G. Clarke (AMRL); J. E. Bohlke and E. B. Bohlke (ANSP); J. E. McCosker (CAS); R. W. Yerger (FSU); C. E. Dawson (GCRL); R. G. Gilmore, Jr. and P. A. Hastings (IRCZM); D. F. Markle and L. Van Guelpen (ARC); D. G. Smith (MBI); W. L. Fink and K. E. Hartel (MCZ); W. J. Richards, T. C. Potthoff (NMFS-M); J. Finucane (NMFS-PC); M. P. Fahay (NMFS-SH); P. H. J. Castle (VUM); B. W. Stender (SCMRI); J. D. McEachran (TCWC); C. R. Robins, C. H. Robins and E. D. Houde (UMML); D. A. Hensley (UPRM); W. H. Krueger (URIZ); D. M. Milliken, T. Lancraft (USF); V. G. Springer and K. Tighe (USNM); J. E. Olney and J. A. Musick (VIMS). Special thanks are due to the late J. E. Bohlke, E. B. Bohlke (ANSP), and J. E. McCosker (CAS) for sharing their knowledge of and data on adult ophichthids, and to D. G. Smith (MCZ) and P. H. J. Castle (NMNZ) for sharing their knowledge of leptocephalus identification. Many colleagues have provided assistance and encouragement throughout this study. I am particularly grateful to K. M. Peters (FDNR) and D. A. Hensley (UPRM) for their stimulating discussions on the problems of larval fish identification and to J. E. Darovec, Jr., G. E. Bruger, M. A. Culbreth, and R. Muller (FDNR) for statistical and computer assistance. J. V. Gartner, Jr., and J. E. Darovec, Jr., (FDNR) provided comments, suggestions, and constructive criticism of an early version of this paper. Above all I thank my wife Judy. Without her patience, understanding, encouragement, and occasional gentle prodding, this study would not have been completed.

Growth Stages. Ophichthid larvae have four morphologically distinct growth stages which are defined as follows. Engyodontic stage (Figs. 759, 760, 782A,B, 794A,B): The term engyodontic is derived from the Greek words engys meaning near or narrow and odon meaning tooth to describe the narrowbased teeth present in the larvae of this stage. 764

Ophichthid Leptocephali

765

0,16

A Engyodontic

0.15

0.14 O

0.13

UI j

0.12-1

z

Stage

• Euryodontic

Stage

* Metamorphic

Stage

0.11-1 0.10-

0.09-

UI

-J

o
^)))»))))))))»)m

^

LIV 2 & GB

DFO

uv 1

^mmimmn^ LIV 2 & GB

FIGURE 842. Gordiichthys irretitus: A. FDNR 16979L, 14 mm SL engyodontic stage. B-D. FDNR 16977L, 62 mm SL euryodontic stage. E. FDNR 16981L, 78 mm SL metamorphic stage. July 1969. FDNR 11622L (1, 17), 28°46'N, 84°37'W, 12 Aug. 1969. FDNR 11621L (1, 26), 28°54'N, 85°07'W, 12 Aug. 1969. FDNR 11620L (1, 72), 29°17'N, 85°40'W, 10 Aug. 1969. Mexico: ANSP156606 (1,74), 20°48'N, 92°56'W, 29 July 1977.

Gordiichthys irretitus Jordon and Davis, 1891 Figures 841, 842, Tables 87,98,100 Distinctive Characters. More than 109 nephric and 190 total myomeres; dorsal-fin origin anterior to myomere 23; up to 11 low gut loops; little or no pigment in body wall ventral to gut except under liver lobes; last two major vertical blood vessels widely separated, a few minor vertical blood vessels between them. Description. Total myomeres 192-214; nephric

myomeres 110-127; preanal myomeres 112-128; predorsal myomeres 13-21 (Tables 98,100). Dorsal-fin rays 819 (n = 1); anal-fin rays 290-341 (n = 2). Dorsal-fin origin above or near level of first liver lobe. Branchiostegal rays 27-31 (n = 2). Basibranchial 2 and 4 present; basibranchial 3 absent; hypobranchial 4 possibly present but reduced and united with a reduced ceratobranchial 5. Three hypurals supported on 1% terminal centra. Up to 11 low gut loops which may be discernible only by pigment on dorsal surface of gut at gut loops, or not at all; nephros terminates 0-3 myomeres anterior to anus. Pigmentation. Essentially as in B. bascanium except fewer patches on dorsal surface of gut; pigment patches marking gut loops frequently more extensive than those between gut loops; pigment in body wall ventral to gut usually occurs only

Ophichthid Leptocephali

869

DFO

B UV 1

FIGURE 843. Gordiichthys lefoyi: ANSP 156605, 57 mm SL euryodontic stage.

under liver lobes, but occasionally there may be 2-3 spots posterior to liver lobes. Size. The largest engyodontic stage specimen examined was 24 mm. Euryodontic stage specimens were 26-84 mm. Variation. Gordiichthys irretitus larvae from the Gulf of Mexico and from the Atlantic north of Cuba had a total myomere range of 192-206 (n = 17, x = 197.9), a nephric myomere range of 110-122 (n = 24, x = 117.5) and a predorsal myomere range of 13-17 (n = 9, x = 15.2). Larvae identified as Gordiichthys irretitus from south of 12°N had a total myomere range of 202-214 (n = 8, x = 208.5), a nephric myomere range of 119127 (n = 9, x = 123.9), and a predorsal myomere range of 16-21 (n = 6, x = 18.5). The differences in myomere ranges could be geographic variation, or the more southerly group could be a species other than G. irretitus. Identification. These larvae are identified as Gordiichthys irretitus based on dorsal-fin origin; ratio of nephric to total myomeres; gill arch and caudal osteology; number of branchiostegal rays; and a comparison of myomere and vertebral numbers between larvae and adults. Distribution (Fig. 841). Gordiichthys irretitus larvae are known from north of Bermuda, Florida Atlantic, the Gulf of Mexico, the Bahamas, and from the Lesser Antilles to Suriname.

Study Material. 33 specimens 14-84 mm. SCOTIAN SHELF TO BAHAMAS: MCZ 61600 (1, 75). SCMRI 0574070 (1, 22). ANSP 156600 (1, 57), 156601 (1, 26). FDNR 16982L (1, 84). GULF OF MEXICO: Florida: FDNR 16980L (1, 22), 16981L (1, 78), 16977L (6, 60-72), 16978L (1, 79), 16979L (1, 14). Mexico: ANSP 156602 (8, 15-44), 156603 (1, 49). LESSER ANTILLES TO SURINAME: FDNR 16982L (1, 50). MCZ 64453 (1, 52). ANSP 156604 (4,20-51). MCZ 61601 (1, 28), 61602 (1, 53), 61603 (1, 33-1-, tail broken).

Gordiichthys lefoyi McCosker and J. E. Bohlke, 1984 Figures 843, 844, Tables 87, 98, 101 Distinctive Characters. Dorsal-fin origin anterior to myomere 21; a series of small, frequently stellate melanophores along dorsal midline; gut loops very low, frequently indistinguishable; last two major vertical blood vessels widely separated, a few minor vertical blood vessels between them. Description. Total myomeres 167-175; nephric myomeres 101-106; preanal myomeres 102-107; predorsal myomeres 13-18 (Tables 98,101). Dorsal-fin rays 650 (n = 1); anal-fin rays 277 (n = 1). Dorsal-fin origin above or near level of first liver lobe. Branchiostegal rays 24 (n = 1). Basibranchials 2 and 4 present; basibranchial 3 reduced or absent; hypobranchial 4 absent; ceratobran-

870

Fishes of the Western North Atlantic, Part 9

TABLE 101. Frequency distribution of myomere counts of Gordiichthys leibyi and Gordiichthys randalli. Total

leibyi randalli

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

1

1

1

1

4 1

3

1 -

1 5

1 2

1

3

1

1

1

1

106

Nephric

leibyi randalli

97

98

99

100

101

102

103

104

105

2

1

2

7

2 2

6 3

2 -

2 1

1

2 Predorsal

Preanal leibyi randalli

97

98

99

100

101

102

103

104

105

106

107

13

14

15

16

17

18

19

6

3 1

-

4

2 2

1

1

6 2

1

1

1 1

1

1

2 1

3 -

1 2

2 4

4

chial 5 moderately developed. Three hypurals supported by 1% terminal centra. Gut loops or swellings very low, frequently indistinguishable except at liver lobes, exact number could not be determined. Last two major vertical blood vessels 8-14 myomeres apart, a few minor vertical blood vessels between them. Nephros terminates 0-3 myomeres anterior to anus. Pigmentation. Head pigment consists of a few spots occasionally present near base of teeth on anterior half of upper jaw; a few spots occasionally present ventral to throat. Dorsal margin pigment consists of a series of small, frequently stellate melanophores in body wall along dorsal midline, starting near head, ending mid-tail. Midline pigment consists of spots or streaks on most myosepta; 3-4 subcutaneous patches on tail just ventral to notochord; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. Ventral margin pigment consists of a few spots occasionally on esophagus near pectoral-fin base; numerous small patches on dorsal surface of gut; a series of small, sometimes stellate melanophores in body wall ventral to gut from near heart to end of liver lobes, sometimes a few spots posterior to liver lobes; pigment on ventral surface of most anal-fin pterygiophores. Size. Euryodontic stage specimens examined were 31-81 mm.

Identification. This series of larvae is identified as Gordiichthys leibyi based on dorsal-fin origin, ratio of nephric to total myomeres, gill arch and caudal osteology, number of branchiostegal rays, and a comparison of larval nephric and total myomeres with adult precaudal and total vertebrae. A discussion of the differences between G. leibyi, Ethadophis akkistikos and Bascanichthys scuticaris is included in the Identification section of E. akkistikos (p. 875). Distribution (Fig. 844). Gordiichthys leibyi larvae

40»

25-

FIGURE 844. Distribution of Gordiichthys leibyi and Gordiichthys randalli larvae based on material examined.

Ophichthid Leptocephali

871

FIGURE 845, JGordiichthys randalli: A. FDNR 17001L, 21 mm SL late engyodontic stage. B-D. ANSP 156643, 73 mm SL euryodontic stage.

are known from South Carolina and the Gulf of Mexico. Study Material. 16 specimens 31-84 mm. SCOTIAN SHELF TO SOUTH CAROLINA: ARC 8601003 (1, 84), 43°49'N, 63°59'W, 8 Oct. 1981. SCMRI 0574168 (2, 51), 32°31'N, 79°01'W, 14 Aug. 1974. SCMRI 0573321 (1, 39), 32°06'N, 79°12'W, 15 July 1973. GULF OF MEXICO: Florida: FDNR 16988L (1, 81), 27°37'N, 83°58'W, 3 July 1966. FDNR 16986L (2, 45-56), 28°54'N, 85°07'W, 12 Aug. 1969. FDNR 16987L (6,31-59), 29°17'N, 85°40'W, 10 Aug. 1969. FDNR 16984L (1, 42), 29°45'N, 86°07'W, 6 Aug. 1969. FDNR 16985L (1, 55), 29°47'N, 87°52'W, 8 Aug. 1969. Mexico: ANSP 156605 (1, 57), 20°50'N, 92°58'W, 29 July 1977.

?Gordiichthys randalli

McCosker and J. E. Bohlke, 1984 Figures 844, 845, Tables 87, 98, 101 Callechelys sp. cf. springeri (not Gordiichthys springeri Ginsburg, 1951, = Callechelysguineensis Osorio, 1894). Leiby, 1984b: 412, figs. 20-22 (descr, western Gulf of Mexico to northern Brazil).

Distinctive Characters. Ten moderate gut loops; dorsal-fin origin anterior to myomere 23; more than 94 nephric and 168 total myomeres; nephros terminates on last gut loop; pigment on medial face of lower jaw near Meckel's cartilage /quadrate juncture; last two major vertical blood vessels 3-5 myomeres apart. Description. Total myomeres 171-181; nephric myomeres 97-105; preanal myomeres 97-105; predorsal myomeres 15-19 (Tables 98,101). Analfin rays 220-279 (n = 4, x = 252.2). Dorsal-fin origin slightly posterior to level of first liver lobe. Branchiostegal rays 31 (n = 1). Basibranchial 2 and 4 present; basibranchial 3 reduced; hypobranchial 4 reduced or absent, united with moderately developed ceratobranchial 5 when present. Three hypurals supported on 1V4 terminal centra. Ten moderate gut loops; nephros terminates on last gut loop, 0-2 myomeres anterior to anus. Pigmentation. No head pigment in early engyodontic stage specimens. By euryodontic stage

872

Fishes of the Western North Atlantic, Part 9

head pigment consists of numerous small melanophores at base of teeth on upper jaw; 1-3 spots on medial face of lower jaw near Meckel's cartilage/ quadrate juncture; a chevron shaped series of melanophores ventral to throat. Midline pigment in early engyodontic stage limited to 1-3 subcutaneous pigment patches on tail just ventral to notochord, occasionally extending to ventral edge of myomeres; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. By euryodontic stage midline pigment increases to include occasionally stellate melanophores or streaks of pigment on most myosepta; 6-7 subcutaneous pigment patches on tail just ventral to notochord. Ventral margin pigment in early engyodontic stage limited to patches on dorsal surface of esophagus near pectoral-fin base and on dorsal surface of each gut loop. By euryodontic stage ventral margin pigment increases to include patches on dorsal surface of gut approximately midway between each gut loop which are smaller than patches marking gut loops; occasionally some pigment in body wall lateral to a few gut loops; patches of occasionally stellate melanophores ventral to midpoint of esophagus and ventral or ventrolateral to liver lobes, and occasionally ventral to a few gut loops; pigment on ventral surface of most anal-fin pterygiophores. Size. A10 mm engyodontic stage specimen had a small amount of yolk remaining under the gut. Hatching probably takes place at 7-8 mm. The largest engyodontic stage specimen examined was 25 mm. Euryodontic stage specimens were 3196 mm; one metamorphic stage specimen was 85 mm. Identification. Leiby (1984b) tentatively placed these larvae in the tribe Callechelyini because some specimens had a fourth hypobranchial which was more reduced than in other Callechelyini but more developed than in any Bascanichthyini he had examined. He had reservations about this allocation because some specimens apparently lacked a fourth hypobranchial and all specimens had three hypurals, conditions he considered unusual for the Calleche-

lyini but common in the Bascanichthyini. Leiby (1984b) then tentatively identified the larvae as Callechelys springeri because the adults of C. springeri were the only known callechelyin with meristics approaching those of the larvae. He expressed reservations because agreement between the limited adult data and the larval data was weak; he also indicated that the larvae might be an unidentified bascanichthyin. Identification of these larvae as C springeri is further weakened by doubts that C. springeri is distinct from C. guineensis (McCosker et aL, p. 312). Subsequent to Leiby (1984b), McCosker and J. E. Bohlke (1984) published a description of the new species Gordiichthys randalli, a species which differs somewhat in morphology from other species of Gordiichthys. While the meristics of adult G. randalli do not perfectly match the meristics of these larvae, they are a closer match than the meristics of the nominal species C. springeri. Consequently, these leptocephali are tentatively reidentified as G. randalli based on their caudal osteology, the absence or reduced condition of hypobranchial four, their pigment pattern, and the agreement of adult and larval meristics. Distribution (Fig. 844). ?Gordiichthys randalli larvae are known from the western Gulf of Mexico through the Caribbean to northern Brazil. Study Material. 19 specimens 10-96 mm. GULF OF MEXICO: Texas: FDNR 17001L (1, 21), 27°34'N/ 96°50'W, 10 Sept. 1976. FDNR 17002L (1, 23), 27°24'N/ 96°36'W/ 9 Nov. 1976. FDNR 17003L (1, 10), 27°24'N/ 96°29'W, 14 Sept. 1976. FDNR 17004L (1, 15), 26°10'N/ 96°24'W, 13 Sept. 1975. Mexico: ANSP 156631 (1, 69), 25°28'N/ 96°08'W/19 Nov. 1975. ANSP 156632 (1, 31), 24°02'N/ 97°05'W, 21 Apr. 1976. ANSP 156633 (1,70), 23°20'N, 96°51'W/ 17 Nov. 1975. ANSP 156634 (1, 59), 20°37'N, 96°40'W, 16 Nov. 1975. ANSP 156635 (1, 82), NE of Veracruz, 7 Aug. 1976. ANSP 156636 (1, 55), NE of Veracruz, 7 Aug. 1976. ANSP 156637 (1, 25), 19°38'N, 95°30'W, 30-31 July 1977. ANSP 156638 (1, 23), 19°26'N, 95°25'W, 17 Apr. 1976. COLOMBIA: ANSP 156639 (1, 82), 10°16'N, 76°00'W, 14 July 1966. ANSP 156640 (1,44), 09°55'N, 76°20'W, 16 July 1966. ANSP 156641 (1, 71), 09°17'N, 76°30'W, 13 July 1966. MEXICO: Quintana Roo: ANSP 156642 (1, 32), 18°45'N, 87°30'W, 23 July 1977. ANSP 156643 (1,73), approximately 7 km off San Miguel,

Ophichthid Leptocephali

873

DFO

LIV 2 & GB

B

FIGURE 846. Phaenomonas longissima: ANSP 156607, 65 mm SL eury odontic stage. Cozumel Island, 27 July 1975. BRAZIL: Uncatalogued (1, 96, disintegrated after clearing and staining), 05°54'N, 52°04'W, 8 July 1968. FDNR 17005L (1, 85), ?location, ?date.

IPhaenomonas longissima (Cadenat and Marchal, 1963) Figures 846,847, Tables 87, 98, 102 Distinctive Characters. More than 140 nephric and 200 total myomeres; dorsal-fin origin anterior to myomere 20; gut loops very low, frequently undetectable except at liver lobes. Description. Total myomeres 208-219; nephric myomeres 141-149; preanal myomeres 141-149; predorsal myomeres 11-17 (Tables 98,102). Dorsal-fin origin above first gut loop. Branchiostegal rays 33 (n = 1). Gut loops very low, frequently undetectable except at liver lobes. Last two major vertical blood vessels widely separated, some mi-

nor vertical blood vessels between them. Nephros terminates 0-1 myomere anterior to anus. Pigmentation. No head pigment in specimens examined. Midline pigment consists of spots or streaks on most myosepta; 4 small subcutaneous patches on tail just ventral to notochord; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. Ventral margin pigment consists of numerous patches on dorsal surface of gut; pigment in body wall lateral and ventrolateral to esophagus near pectoral-fin base; patches of frequently stellate melanophores in body wall ventral to liver lobes; a few widely spaced small patches in body wall ventral to gut from liver lobes to near anus; pigment on ventral surface of most anal-fin pterygiophores. Size. Euryodontic stage specimens were 40-77 mm; metamorphic stage specimens were 82-94 mm.

53

TABLE 102. Frequency distribution of myomere counts of Phaenomonas longissima, Ethadophis akkistikos and lEthadophis sp. leptocephali. Total

160 Phaenomonas longissima Ethadophis akkistikos ?Ethadophis sp.

2

161

1

162

3

163

1

164 —

165 3

166 —

167

.,.

2

208

209

210

211

212

1

1

1

-

1

..,

216 1

217

218

219

-

-

1

5

5

1

^ ^

Nephric

95 Phaenomonas longissima Ethadophis akkistikos ?Ethadophis sp.

1

95 Phaenomonas longissima Ethadophis akkistikos ?Ethadophis sp.

1

96 1

96 —

97 —

97 1

98

1

98 1

99

1

99 —

100

5

100 1

101

2

101 3

138

102

2

102 4

103

...

141

142

143

144

145

2

—

1

—

3

Phaenomonas longissima Ethadophis akkistikos lEthadophis sp.

1

8

9

10

1

3 3

%

Preanal

Sr

...

138

...

2

141

142

143

144

145

146

2

—

1

—

2

1

...

149 1

$ ?i* & a

to

Predorsal

7

I

149

1

1 6

...

11

12

13

14

15

16

17

1

—

1 3

— 1

1 3

2 2

2

Ophichthid Leptocephali Identification. These larvae are placed in the tribe Bascanichthyini based on their anterior dorsal-fin origin, ratio of nephric to total myomeres, very low gut loops, number of branchiostegal rays, and pigmentation. They are tentatively placed in Phaenomonas because the unusually high number of nephric myomeres indicates that the adults will have an extremely elongate body and short tail, a characteristic of all Phaenomonas and a few Ethadophis. The meristics of P. longissima are consistent with those of these larvae, but adult P. longissima are known only from St. Helena and Ascension Islands and from off Brazil. Consequently the identification of these larvae as P. longissima is tentative. Distribution (Fig. 847). Phaenomonas longissima larvae are known from north of Bermuda, the Gulf of Mexico, the western Caribbean, and off Suriname. Study Material. Seven specimens 40-94 mm. MCZ 61604 (1, 94), 38°15'N/ 66°32'W, 31 July 1976. FDNR-SML 1000-000 (1, 64), 26°30'N, 86°00'W, 19 Apr. 1982. ANSP 156607 (1, 65), 20°14'N, 87°15'W, 15 Feb. 1977. FDNR 16697L (1, 77), 20°00'N, 85°00'W, 25 Mar. 1972. ANSP 156608 (2, 40-47), 09°28'N, 55°35'W, 13 July 1968. ANSP 156609 (1, 82), ?location, ?date.

Ethadophis akkistikos McCosker and J. E. Bohlke, 1984 Figures 847, 848, Tables 87, 98,102 Distinctive Characters. Two to eight low gut loops, gut loops may be discernible only by pigment patch on dorsal surface of gut or not at all; dorsal-fin origin anterior to myomere 20; last two major vertical blood vessels 8-14 myomeres apart, a few minor vertical blood vessels between them; 95-102 nephric myomeres. Description. Total myomeres 160-167; nephric myomeres 95-102; preanal myomeres 95-103; predorsal myomeres 13-16 (Tables 98,102). Analfin rays 203 (n = 1). Dorsal-fin origin above first liver lobe. Branchiostegal rays 24 (n = 1). Basibranchial 2 present; basibranchials 3-4 weakly developed, probably absent in some specimens; hypobranchial 4 possibly present but reduced and united with a reduced ceratobranchial 5.

875

85°

70°

55*

40*

25*

FIGURE 847. Distribution of Phaenomonas longissima, Ethadophis akkistikos and Ethadophis sp. larvae based on material examined.

Three hypurals supported by IVi terminal centra. Two to eight low gut loops which may be detectable only by pigment on dorsal surface of loops, or not at all. Last two major vertical blood vessels 8-14 myomeres apart, some minor vertical blood vessels between them. Nephros terminates 0-2 myomeres anterior to anus. Pigmentation. Pigment essentially as in Bascanichthys bascanium except generally fewer pigment patches on dorsal surface of gut and few spots in body wall ventral to gut. Size. The largest engyodontic stage specimen examined was 22 mm. Euryodontic stage specimens were 22-78 mm. Identification. This series of larvae is identified as Ethadophis akkistikos based on dorsal-fin origin, ratio of nephric to total myomeres, gill arch osteology, and agreement of larval nephric and total myomere counts with adult precaudal and total vertebral counts. Larvae of Ethadophia akkistikos and G. leibyi are very similar but are distinguished from each other by the presence of a series of small stellate melanophores along the dorsal midline of G. leibyi larvae and by a difference in the number of nephric and total myomeres. E. akkistikos larvae have 95-102 nephric (x = 99.5) and 160-167 total (x = 162.8) myomeres, G. leibyi larvae have 101-

Fishes of the Western North Atlantic, Part 9

876 DFO

wm

-———~~

FIGURE 848. Ethadophis akkistikos: ANSP 156595, 72 mm SL euryodontic stage.

106 nephric (x = 102.9) and 167-175 total (x = 171.1) myomeres. The only other known western North Atlantic bascanichthyin larva with meristics broadly overlapping these two species is B. scuticaris. Both E. akkistikos and G. leibyi larvae generally have more nephric myomeres than B. scuticaris larvae, the last two major vertical blood vessels of B. scuticaris are only 3-5 myomeres apart while they are 8-14 myomeres apart in E. akkistikos and G. leibyi, and B. scuticaris has seven low but usually discernible gut loops. Distribution (Fig. 847). Ethadophis akkistikos larvae are currently known only from the western Gulf of Mexico. Study Material 12 specimens 19-78 mm. FDNR-SML 8141-000 (1, 53), 29°00'N/ 93°00'W, 20 June 1983. FDNR-SML 8107-003 (1, 35), 28°00'N/ 95°00'W, 5 July 1983. FDNR 16989L (1,22), 27°55'N, 96°20'W, 7 June 1976. ANSP 156592 (1, 22), 24°02'N, 97°07'W, 21 Apr. 1976. ANSP 156593 (1, 19), 24°02'N, 97°05'W, 21 Apr. 1976. ANSP 156594 (1, 35), NE of Veracruz, Mexico, 6 Aug. 1976. ANSP 156595 (1,72), NE of Veracruz, Mexico, 7 Aug. 1976. ANSP 156596 (1, 78), 20°37'N, 96°00'W, 1 Aug. 1977. ANSP 156597 (2, 46-52), 20°46'N, 97°57'W, 1 Aug. 1977. ANSP 156598 (1,36), 19°30'N, 95°28'W, 5 Aug. 1976. ANSP 156599 (1,39), 19°29'N, 95°28'W, 5 Aug. 1976.

lEthadophis species Figures 847, 849, Tables 98, 102 Microrhynchus sp. Leiby, 1982: 227, figs. 9, 12 (descr., 12°16'N, 59°29'W).

Distinctive Characters. More than 200 total and 130 nephric myomeres; low gut loops; distinct pigment patches along dorsal margin of body and tail. Description. Total myomeres 217; nephric myomeres 138; preanal myomeres 138; predorsal myomeres 6 (Tables 98, 102). Dorsal-fin origin anterior to level of first liver lobe. Branchiostegal rays 26. Basibranchial 2 reduced, basibranchials 3-4 absent; hypobranchial 4 absent; ceratobranchial 5 reduced. Three hypurals supported by Wi terminal centra. Gut loops low, exact number not determined; nephros terminates over anus. Pigmentation. Head pigment consists of stellate melanophores at base of teeth on anterior half of upper jaw; patch at tip of lower jaw; several spots on medial face of lower jaw near Meckers cartilage/quadrate juncture; numerous spots on side of head lateral to medulla; some pigment ventral to throat. Dorsal margin of body and tail marked by groups of small, occasionally stellate melanophores; groups placed 2-8 myomeres apart starting near myomere 25. Midline pigment consists of spots or streaks on every 3rd-8th myoseptum; groups of stellate melanophores in body wall adjacent to many pigmented myosepta; 3 subcutaneous pigment patches on tail just ventral to notochord; pigment on dorsal surface of nerve cord at tail tip. Pigment on myomeres between level of no-

Ophichthid Leptocephali

LIV 1

877

UV 2 & GB

DFO

FIGURE 849. lEthadophis sp.: MCZ 55464, 85 mm SL euryodontic stage.

tochord and gut consisting of variable amounts of pigment on myosepta and myomeres; pigment occurs every 2-6 myomeres and may occur anywhere from just ventral to level of notochord to just dorsal to level of gut. Ventral margin pigment consists of patches on dorsal surface of esophagus and in body wall near pectoral-fin base; numerous patches along dorsal surface of gut occurring at intervals of 25 myomeres; 8 groups of stellate melanophores in body wall ventrolateral to heart, esophagus and liver lobes; pigment on anal-fin pterygiophores occurring in alternating groups of lightly and darkly pigmented pterygiophores which may give the appearance of interrupted pigment at base of anal fin. Size. One 85 mm euryodontic stage specimen examined. Identification. Leiby (1982) placed this specimen in the tribe Sphagebranchini despite its high nephric to total myomere ratio because it lacked even rudimentary dorsal-fin pterygiophores anterior to myomere 200 although it had well developed muscle fibers and a dorsal thickening extending forward to myomere six. Larval Bascanichthyini and Callechelyini generally have at least rudimentary pterygiophores anterior to the anus before they reach the stage of development of this specimen. Leiby tentatively identified the

specimen as Microrhynchus sp. because of its many similarities to four specimens which Blache (1977) identified as Microrhynchus sp. cf. forresti. McCosker and J. E. Bohlke (1984) have since found that Microrhynchus forresti is not a finless sphagebranchin but is an Ethadophis, a genus with low median fins. Because of this finding, and because the caudal osteology of this specimen is unlike that of any of the finless sphagebranchins but is typically bascanichthyin, I now feel that the many morphological similarities between this specimen and many bascanichthyin larvae make it more prudent to provisionally assign the specimen to the genus Ethadophis in the tribe Bascanichthyini. I am assuming that the muscle striations and dorsal thickening which reach myomere six are the true indicators of its dorsalfin origin, and that the specimen is unusual in its late development of dorsal-fin pterygiophores. An unequivocal determination of the proper placement of this specimen must await either the discovery of metamorphic larvae of this species, or adults of this species. Distribution (Fig. 847). This species is known from a single 85 mm specimen (MCZ 55464) collected south of Barbados at 12°16H 59°29W, ATLANTIS II78,10-foot Isaacs-Kidd midwater trawl oblique tow, 480 m to surface, R. H. Backus and party collectors, 29 September 1973.

Fishes of the Western North Atlantic, Part 9

878

UV 2 & GB

j$m»^ S»))@)^^

DFO

LIV 1

LIV 2 & GB DFO

FIGURE 850. Caralophia loxochila: A. ANSP 156591, 64 mm SL euryodontic stage. B, C. FDNR 16691L, 72 mm SL early metamorphic stage.

Caralophia loxochila Bohlke, 1955 Figures 850, 851, Tables 87, 98,103 Distinctive Characters. Seven low gut loops; last two major vertical blood vessels widely separated, a few minor vertical blood vessels between them; dorsal-fin origin above or just anterior to level of second liver lobe; less than 160 total myomeres. Description. Total myomeres 142-154; nephric myomeres 79-86; preanal myomeres 80-86; predorsal my omeres 20-23 (Tables 98,103). Anal-fin

rays 182-225 (n = 3). Dorsal-fin origin above or just anterior to level of second liver lobe. Branchiostegal rays 28 (n = 2). Basibranchial 2 absent, basibranchials 3-4 present; hypobranchial 4 absent; ceratobranchial 5 moderately developed Three hypurals on 1 terminal centrum. Seven low but usually discernible gut loops; nephros terminates on last gut loop, 0-2 myomeres anterior to anus. Pigmentation. Essentially as in Bascanichthys bascanium except pigment patches clearly mark gut loops; fewer patches on dorsal surface of gut

Ophichthid Leptocephali

879

TABLE 103. Frequency distribution of myomere counts of Caralophia loxochila and Bascanichthyini sp. leptocephali. Total 142 143 144 145 146 147 148 149 150 151 152 153 154

Caralophia loxochila Bascanichthyini sp.

2

-

-

1 2 2 1 1 - 1

~ 1

1

1 2 -

1-1 1 1

Nephric

79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 Caralophia loxochila Bascanichthyini sp.

1

2

3

2

1 -

-

1 1

4

2

1 -

-

1 1

Preanal

80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 Caralophia loxochila Bascanichthyini sp.

1

1

2

4

1

—

1 2

3

1

2

23

1

-

1

Predorsal Caralophia loxochila Bascanichthyini sp.

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22

1

1

2

-

2

1

between gut loops; generally fewer pigment spots in body wall ventral to gut. Size. Euryodontic stage specimens were 23-90 mm; one metamorphic stage specimen was 72 mm. Identification. These larvae are identified as Caralophia loxochila based on dorsal-fin origin; gill arch osteology; number of branchiostegal rays; and a comparison of myomere and vertebral counts between larvae and adults. Distribution (Fig. 851). Caralophia loxochila larvae are known from South Carolina, Florida Atlantic, the Gulf of Mexico, the Caribbean and the Yucatan Straits. Study Material Eight specimens 23-90 mm. ATLANTIC OCEAN: South Carolina: FDNR 16900L (1, 90), 32°35'N, 78°34'W, 29 Jan. 1968. Florida: FDNR 17037L (1, 67), 29°45'N, 80°49'W, 1 Feb. 1968. GULF OF MEXICO: Florida: ANSP 156588 (2, 28-40), 25°30'N, 82°50'W, Nov. 1973. BELIZE: FDNR 16991L (1, 72), reef flat off Carrie Bow Cay, 22 Nov. 1978. YUCATAN STRAITS: ANSP 156589 (1, 23), 21°31'N, 85°53'W, 8-9 Nov. 1975. ANSP 156590 (1, 41), 21°33'N, 85°53'W, 9 Nov. 1975. ANSP 156591 (1, 64), 21°34'N, 85°56'W, 15 Feb. 1977.

-

3

1

Bascanichthyini species Figures 851, 852, Tables 98, 103 Distinctive Characters. Twelve low gut loops which sometimes can be distinguished only by pigment on dorsal surface of gut at gut loops;

85°

70°

55*

40*

25°

FIGURE 851. Distribution of Caralophia loxochila and Bascanichthyini sp. larvae based on material examined.

Fishes of the Western North Atlantic, Part 9

880 DFO

FIGURE 852, Bascanichthyini sp.: FDNR 16992L, 43 mm SL euryodontic stage.

saddle-shaped groups of melanophores along dorsal margin of body; dorsal-fin origin anterior to level of first liver lobe; 145-154 total myomeres. Description. Total myomeres 145-154; nephric myomeres 90-97; preanal myomeres 92-99; predorsal myomeres 7-11 (Tables 98, 103). Anal-fin rays 223-238 (n = 2). Dorsal-fin origin anterior to level of first gut loop. Branchiostegal rays 25+, development not complete in most advanced specimen examined. Basibranchials 2 and 4 present; basibranchial 3 absent; hypobranchial 4 absent; ceratobranchial 5 reduced. Two hypurals supported on Vi terminal centrum. Twelve low gut loops sometimes discernible only by pigment on dorsal surface of gut at gut loops; nephros terminates on last gut loop, 0-2 myomeres anterior to anus. Pigmentation. No head pigment in specimens examined. Little or no dorsal margin pigment in early engyodontic stage. By euryodontic stage dorsal margin pigment consists of saddle-shaped groups of frequently stellate melanophores every 3-6 myomeres from just behind head to near tail tip. Midline pigment in early engyodontic stage consists of spots on a few myosepta; 1-2 subcutaneous pigment spots on tail just ventral to

notochord, sometimes extending to ventral edge of myomeres; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. By euryodontic stage pigment increases to include spots or streaks on approximately half of all myosepta; 2-3 subcutaneous pigment spots on tail. Ventral margin pigment in early engyodontic stage limited to pigment on a few developing gut loops. By euryodontic stage pigment consists of melanophores on esophagus near pectoral-fin base; generally two groups of melanophores on dorsal surface of esophagus between pectoral fin and first liver lobe; patches on dorsal surface of each gut loop; somewhat smaller patches on dorsal surface of gut between gut loops; a few groups of pigmented anal-fin pterygiophores, most pterygiophores unpigmented. Size. The largest engyodontic stage specimen examined was 15 mm. Euryodontic stage specimens were 23-81 mm. Identification. These larvae are identified as Bascanichthyini sp. based on the ratio of nephric to total myomeres, dorsal-fin origin, gill arch osteology, and the similarity of gut loop morphology to that of B. bascanium. The meristics of these larvae do not match the meristics of any known western North Atlantic bascanichthyin. Avail-

Ophichthid Leptocephali able data are not sufficient to assign these larvae to genus. Distribution (Fig. 851). Bascanichthyini sp. larvae are known from the east coast of Florida and the Gulf of Mexico. Study Material. 15 specimens 7-81 mm. FLORIDA ATLANTIC: FDNR 16992L (1, 43), 26°46'N, 79°56'W/19 Oct. 1971. GULF OF MEXICO: Florida: FDNR 16993L (1, 15), 25°26'N, 82°30'W, 10 May 1969. FDNR 16994L (1, 51), 28°54'N/ 85°07'W, 12 Aug. 1969, FDNR 16995L (1, 37), 28°54'N, 85°07'W, 12 Aug. 1969, FDNR 16996L (1, 49), 29°17'N, 85°40'W, 10 Aug. 1969. Mexico: ANSP 156582 (1, 81), 23°01'N/ 91°01'W/ 17 Feb. 1977. ANSP 156583 (1, 10), 22°25'N, 89°53'W, 13 Apr. 1976, ANSP 156584 (5, 7-14), 22°26'N, 89°52'W/ 13 Apr. 1976. ANSP 156585 (1, 23), 22°21'N/ 89°46'W/ 17 Feb. 1977. ANSP 156586 (1, 55), 22°16'N/ 88°57'W/ 8 Nov. 1975. ANSP 156587 (1, 56), ?location, ?date.

TRIBE CALLECHELYINI Characters. Western North Atlantic larvae of the tribe Callechelyini have a relatively long gut and nephros. Nephric myomeres range from 5673% of total myomeres. The nephros terminates on the last gut loop. Dorsal-fin origin in all western North Atlantic larval Callechelyini is anterior to myomere 19. Late in metamorphosis or early in the glass eel stage the dorsal fin migrates anteriorly to its adult position anterior to myomere two (Table 104). All callechelyin larvae have well developed pectoral fins and a cartilaginous support structure. Late in metamorphosis or early in the glass eel stage the pectoral fin is resorbed, the cartilaginous support structure is reduced and migrates posteriorly. All callechelyin larvae have well developed anal fins. The genus Letharchus lacks an anal fin as an adult although reduced pterygiophores are present beneath the integument in some adult specimens. Late in metamorphosis or early in the glass eel stage larval Letharchus resorb the anal-fin rays and the pterygiophores are reduced. In other species the anus and anal fins migrate anteriorly to their adult positions (Table 104). Gut morphology and pigmentation are vari-

881

able in the Callechelyini, but not as much as in the Bascanichthyini. Gut loops range from moderate to pronounced, never like the low gut loops present in some Bascanichthyini. Pigmentation in the Callechelyini is generally distinctive and frequently useful for species identification. The gill arches of the Callechelyini are reduced although not as much as in the Bascanichthyini. There is a moderate amount of inter- and intraspecific variation in which elements are present. Basibranchial 1 is always present, basibranchials 2-4 are variously present, reduced or absent; hypobranchial 4 is always present and may be united with or separate from ceratobranchial 5; ceratobranchial 5 may be moderately developed, reduced or absent (Figs. 853, 855). The number of branchiostegal rays in the Callechelyini ranges from 24-31. There is intraspecific variation in the number of branchiostegal rays, but it is generally limited to 10-15% of the total; e.g., Letharchus velifer has 28-31. The hypurals of the Callechelyini are supported on Vi, 1, or 1 Vi terminal centra. Most species have two hypurals which are united only at their bases or not at all (Fig. 854). One species tentatively placed in the Callechelyini has three hypurals with a morphology similar to that seen in the Bascanichthyini (Fig. 855). Aprognathodon platyventris Bohlke, 1967 Figures 856, 857, Tables 87,104, 105 Aprognathodon platyventris. Leiby, 1984b: 401, figs. 1-5 (descr., Florida Atlantic, Gulf of Mexico, the Bahamas, Grand Cayman Island, Yucatan Straits).

Distinctive Characters. Nine moderate gut loops; dorsal-fin origin anterior to myomere 12; less than 162 total myomeres; pigment on notochord medial to some pigmented myosepta. Description. Total myomeres 149-159; nephric myomeres 96-102; preanal myomeres 97-104; predorsal myomeres 5-10 (Tables 104,105). Dorsal-fin rays 493 (n = 1); anal-fin rays 183-211 (n = 5, x = 193.4). Dorsal-fin origin anterior to level of first liver lobe. Branchiostegal rays 27 (n = 1). Basibranchial 2 present or absent; basibranchials

8

TABLE 104. Comparison of adult and larval frieristics for western North Atlantic members of the tribe Callechelyini. Species

Total

n

s

Preanal

x

2.10

93-99 97-104

96.3 100.0

9 13

103.1

2 19

2.04

96-103 100-109

99.4 104.3

82-88 82-92

84.4 87.1

13 191

1.56 1.75

80-87 85-95

2.21 2.37

98 94-100

97.6

1 22

1.87

12 13

3.41 3.25

116-120 111-120

117.7 114.8

6 17

142.1 143.2

7 46

1.68 2.40

84-86 81-88

85.0 84.7

151.0

7

2.00

102-109

104.3

s

s

DFO

x

n

1.91

H 5-10

8.0

11 12

5 19

2.35

H-l 7-11

0.4 9.3

7 15

1.29

84.2 89.6

19 195

1.79

1-2 8-13

1.4 10.0

15 142

1.04

£ 3

95-101 97-102

96.9 99.8

12 22

1.44 1.68

H 11-15

12.4

12 15

1.35

jl ^

1.51 2.41

111-120 112-121

115.9 116.2

11 17

2.70 2.19

H 6-10

7.4

10 9

1.59

~X-

5 63

0.71 1.59

80-85 82-89

82.7 85.8

7 64

1.60 1.68

H 9-16

12.9

36

7

2.36

103-110

105.6

7

2.37

11-13

x

n

s

Nephric

x

Aprognathodon platyventris Adults 148-152 Leptocephali 149-159

150.5 153.2

14 13

2.70

96 96-102

98.9

2 13

Letharchus aliculatus Adults 155-164 Leptocephali 153-163

159.1 158.3

8 18

3.01

96 99-107

Letharchus velifer Adults Leptocephali

136-144 133-145

140.3 139.6

22 180

2.15

Callechelys bilinearis Adults 155-165 Leptocephali 158-166

160.4 163.1

20 23

Callechelys guineensis Adults 172-186 Leptocephali 174-184

179.2 177.1

Callechelys muraena Adults 139-144 Leptocephali 138-148 Callechelyini sp. Adults unknown Leptocephali 148-154

n

1.48 £

1.71

Ophichthid Leptocephali

883

FIGURE 853. Representative gill arch osteology of the Tribe Callechelyini: A. Callechelys guineensis: ANSP 156339, 74 mm SL larva. B. Callechelys guineensis: FDNR 5988, 238 mm SL subadult. C. Callechelys muraena: FDNR 16988L, 72 mm SL larva. D. Callechelys muraena: IRCZM 107:5482, 295 mm SL adult. Scale = 1 mm.

FIGURE 854. Representative caudal osteology of the Tribe Callechelyini: A. Callechelys guineensis: ANSP 156339, 74 mm SL larva. B. Callechelys guineensis: FDNR 5988, 238 mm SL subadult. C. Callechelys muraena: FDNR 16998L, 72 mm SL larva. Scale = 1 mm.

FIGURE 855. Gill arch and caudal osteology of Callechelyini sp.: ANSP 156653,47 mm SL euryodontic stage. Scale = 1 mm.

Fishes of the Western North Atlantic, Part 9

884

uv 1

LIV 2 & GB

B

FIGURE 856. Aprognathodon platyventris: A. ANSP 156611, 16 mm SL engyodontic stage. B. ANSP 156615, 43 mm SL euryodontic stage. C. ANSP 156610, 70 mm SL early metamorphic stage. D, E. ANSP 156615, 53 mm SL euryodontic stage.

3-4 absent; hypobranchial 4 free from reduced ceratobranchial 5. Two hypurals supported by a terminal half centrum. Nine moderate gut loops; nephros terminates on last gut loop, 1-2 myomeres anterior to anus. Pigmentation. No apparent pigment on head in any developmental stage. Midline pigment in engyodontic stage consists of spots on a few myosepta; 2-4 subcutaneous pigment spots on tail just ventral to notochord; pigment on dorsal surface of nerve cord and ven-

tral surface of notochord at tail tip. By euryodontic stage midline pigment complex, consisting of major group of pigment approximately every 10th myoseptum; minor group of pigment every 4th-6th myoseptum between major groups. Major groups consist of streak on myoseptum; pigment on notochord medial to pigmented myoseptum; group of occasionally stellate melanophores in body wall adjacent to pigmented myoseptum. Minor group consists of spots or streak of pigment on myoseptum.

Ophichthid Leptocephali Ventral margin pigment consists of patch on esophagus near pectoral-fin base; pigment on dorsal surface of each gut loop between nephros and gut, and on dorsal surface of gut approximately midway between each gut loop; occasionally stellate melanophores in body wall lateral to each gut loop. No apparent pigment on anal-fin pterygiophores. Size. Engyodontic stage specimens examined were 16 mm; euryodontic stage specimens were 30-77 mm; metamorphic stage specimens were 55-70 mm. Identification. Leiby (1984b) identified the larvae of Aprognathodon platyventris based on dorsal-fin origin; a comparison of gill arch morphology, number of branchiostegal rays, and number of myomeres and vertebrae between larvae and adults. Distribution (Fig. 857). Aprognathodon platyventris larvae are known from the Atlantic coast of Florida, the Gulf of Mexico, the Bahamas, Grand Cayman Island, and the Yucatan Straits. Study Material. 14 specimens 16-77 mm. FLORIDA ATLANTIC: ANSP 156610 (1, 70), 25°57'N, 80°14'W, 3 Sept. 1965. GULF OF MEXICO: Florida: FDNR 11564L (2, 16-30), 24°23'N, 83°13'W, 19 May 1969. BAHAMAS: ANSP 156611 (1,16), 26°28'N, 78°45'W/1 Aug. 1965. ANSP 156612 (1, 55), 25°43'N/ 79°21'W/ 10 July 1965. ANSP 156613 (1,62), 25°38'N/ 79°21'W/ 4 May 1965. GRAND CAYMAN ISLAND: ANSP 105792 (I, 55), off Georgetown, 23 October 1964. YUCATAN STRAITS: ANSP 156614 (1, 49), 20°35'N/ 87°00'W/ 8 Nov. 1975. ANSP 156615 (3, 43-53) 21°38'N, 85°47'W 8 Nov. 1975. FDNR 11565L (1, 77), 21°43'N, 85°38'W, 3 Aug. 1962. FDNR 11563L (1, 64), 22°12'N/ 85°04'W, 19 May 1969. FDNR 11562L (1, 77), 23°03'N/ 85°03'W, 12 May 1969.

885

Description. Total myomeres 153-163; nephric myomeres 99-107; preanal myomeres 100-109; predorsal myomeres 7-11 (Tables 104,105). Dorsal-fin rays 489 (n = 1); anal-fin rays 172-207 (n = 4, x = 188.5). Dorsal-fin origin anterior to level of first liver lobe. Branchiostegal rays 28 (n = 1). Basibranchial 2 present; basibranchials 3-4 absent; hypobranchial 4 present, united with or free from a reduced ceratobranchial 5. Two hypurals supported by a terminal centrum. Ten pronounced gut loops; nephros terminates on last gut loop, 0-2 myomeres anterior to anus. Pigmentation. No head pigment apparent in any specimens examined. Midline pigment consists of streaks on only a few myosepta (at most 25% of myosepta pigmented); 5 subcutaneous pigment patches on tail just ventral to notochord; patches of stellate melanophores in body wall lateral to most or all subcutaneous tail patches; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. Ventral margin pigment consists of patch on dorsal surface of each gut loop between nephros and gut; usually circular patches of stellate melanophores in body wall lateral to each gut loop; pigment on approximately every 5th anal-fin pterygiophore in posterior half of anal fin.

?Letharchus aliculatus McCosker, 1974 Figures 858, 859, Tables 87, 104, 105 Callechelys sp. Leiby, 1984b: 410, figs. 18-19 (descr., Bermuda, Florida Straits, Gulf of Mexico).

Distinctive Characters. Ten pronounced gut loops; dorsal-fin origin anterior to myomere 14; pronounced, usually round, pigment patches in body wall lateral to gut loops; generally no pigment on dorsal surface of esophagus near pectoral-fin base.

95°

70

40»

25-

FIGURE 857. Distribution of Aprognathodon platyventris larvae based on material examined.

TABLE 105. Frequency distribution of myomere counts of Aprognathodon platyventris, Letharchus aliculatus and Letharchus velifer leptocephali. Total

133 134 135 136 137 138 139 140 141 142 143 144 145 , .. 149 . . . 152 153 154 155 156 157 158 159 160 161 162 163 Aprognathodon platyventris Letharchus aliculatus Letharchus velifer

2 1

1

2

11 13 26 38 27 28 20

7

3

422 1

1

— 1

11 3 2

— 2

1 -

2

3

2

1

3

Nephric

82 Aprognathodon platyventris Letharchus aliculatus Letharchus velifer

1

83

2

84

9

85

86

15 43

87

88

57 25

89

90

17 17

91

3

92 .. - 96

97

98

99 100 101 102 103 104 105 106 107

2

2

2

1 1

2

3 1

1 2

2 3

4

5

-

2

1

Preanal

85 86 87 88 Aprognathodon platyventris Letharchus aliculatus Letharchus velifer

89 90

8

12 29 54 40 22

16 10

Predorsal Aprognathodon platyventris Letharchus aliculatus Letharchus velifer

f+

91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 1

1

-*

10 11

5

6

7

8

9

1

1

1 1

5 3 7

2 2 5 2 4 37 55 32

12 13

9

2

2

1

2

3

1 2

4 —

1 1

— 4

1 4

3

2

1

1

1

Ophichthid Leptocephali

887

DFO

FIGURE 858. Letharchus aliculatus: A. FDNR 11625L, 33 mm SL euryodontic stage. B, C. ANSP 156645, 39 mm SL euryodontic stage.

Size. Euryodontic stage specimens examined were 24-71 mm; metamorphic stage specimens were 63-69 mm. Identification. Leiby (1984b) identified these larvae as Callechelys sp. based on gill arch and caudal osteology, gut morphology and pigmentation. However, the meristics of these larvae are consistent with the meristics of Letharchus aliculatus but not with any other known Callechelyini except Callechelys bilinearis whose larvae have been identified. Adult Letharchus have four supraorbital pores whereas adult Callechelys have three. None of these larvae were sufficiently developed to determine the number of supraorbital pores. Adult L aliculatus are known only from the state of Bahia, Brazil, while the larvae are known from the Scotian Shelf to Haiti. Based on the similarity of larval and adult meristics these larvae are here referred to Letharchus aliculatus, but this identification must remain tentative until it can be confirmed or confuted by additional information. Distribution (Fig. 859). ?Letharchus aliculatus larvae are known from the Scotian Shelf to Bermuda, North Carolina, the Florida Straits, Gulf of Mexico and Haiti. Leiby (1984b) erroneously listed these larvae as occurring in the Bahamas. The actual location should have been Bermuda.

Study Material. 19 specimens 24-71 mm. ATLANTIC OCEAN: Scotian Shelf to Bermuda: ARC 8601004 (1, 27), 40°53'N/ 66°47'W, 19 May 1982. MCZ 61616 (1,71), 38°39'N, 66°31'W/ 29 July 1976. MCZ 61617 (1, 68), 38°28'N, 66°31'W/ 30 July 1976. URIZ Ocean Acre 12-6M (1, 63), 33°19'N, 64°04'W, 28 Aug. 1971. North Carolina: MCZ 64454 (3,54-60+, tail of largest specimen broken), 34°38'N, 75°35'W/ 12 Aug. 1978. FLORIDA STRAITS: FDNR-SML 8126-000 (1,54), 24°30'N/ 84°00'W, 15 May 1983. FDNR 11627L (1, 68), 24°48'N/ 84°45'W/ 22 June 1963. GULF OF MEXICO: Florida: FDNR 11623L (1, 43), 28°43'N, 85°54'W, 7 July 1969. FDNR 11624L (1, 34), 28°43'N, 85°54'W, 7 July 1969. FDNR 11625L (1, 33), 28°46'N/ 84°37'W/ 8 July 1969. FDNR 11626L (1, 52), 29°17'N/ 85°40'W, 10 Aug. 1969. Mexico: ANSP 156645 (1, 39), 19°25'N, 95°40'W, 4 Aug. 1976. ANSP 156646 (1, 66), 20°50'N/ 92°58'W, 29 July 1977. ANSP 156647 (1,32), 22°25'N/ 89°21'W/ 25 July 1977. HAITI: FDNR 17006L (1, 63), 19°06'N, 74°36'W, 13 July 1977. ANSP 156648 (1, 24), ?location, ?date. ANSP 156649 (1, 69), ?location, ?date.

Letharchus velifer Goode and Bean, 1882 Figures 859, 860, Tables 87, 104, 105 Letharchus velifer. Fahay and Obenchain, 1978: 473, fig. 27 (descr., North Carolina to Florida). Leiby, 1984b: 415, figs. 23-27 (descr., South Carolina to Florida, Gulf of Mexico).

Distinctive Characters. Generally 8, occasionally 9-10 moderate gut loops; dorsal-fin origin ante-

888

Fishes of the Western North Atlantic, Part 9

25°

FIGURE 859. Distribution of Letharchus aliculatus and Letharchus velifer larvae based on material examined.

rior to myomere 14; less than 147 total myomeres; pigment on many preanal myosepta at midline. Description. Total myomeres 133-145; nephric myomeres 82-92; preanal myomeres 85-95; predorsal myomeres 8-13 (Tables 104,105). Dorsalfin rays 435-495 (n = 2); anal-fin rays 165-227 (n = 23, x = 186.7). Dorsal-fin origin above or anterior to level of first liver lobe. Branchiostegal rays 28-31 (n = 3). Basibranchials 2 and 4 present; basibranchial 3 absent; hypobranchial 4 present, united with reduced ceratobranchial 5. Two hypurals supported by a terminal half centrum. Generally 8, occasionally 9-10 moderate gut loops; nephros terminates on last gut loop 0-4 myomeres anterior to anus. Pigmentation. No head pigment in engyodontic stage larvae. By euryodontic stage head pigment, when present, consists of a few spots at base of teeth on anterior portion of upper jaw; occasionally some pigment at tip of lower jaw; rarely any pigment ventral to throat. Midline pigment in early engyodontic stage limited to 1-2 subcutaneous patches on tail just ventral to notochord, sometimes reaching ventral edge of myomeres; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. By euryodontic stage midline pigment

increases to include occasionally stellate melanophores or streaks on every 2nd-5th myoseptum, occasionally some stellate melanophores in body wall adjacent to some pigmented myosepta; 3-4 subcutaneous patches on tail just ventral to notochord. Ventral margin pigment consists of patch on dorsal surface of esophagus near pectoral-fin base; pigment on dorsal surface of each gut loop; 1-3 small patches on dorsal surface of gut between each gut loop; occasionally some pigment in body wall lateral to each gut loop; pigment on ventral surface of anal-fin pterygiophores in groups of 2-6 pigmented pterygiophores alternating with groups of 2-5 unpigmented pterygiophores. Size. Letharchus velifer larvae are approximately 7 mm at hatching. The largest engyodontic stage specimen examined was 25 mm. Euryodontic stage specimens were 24-71 mm; metamorphic stage specimens were 67-78 mm; one glass eel was 46 mm. Variation. Letharchus velifer is unusual among species with moderately developed gut loops in having a variable number of gut loops. Eight gut loops were present in 82.3% of specimens examined; nine gut loops in 12.7% and ten gut loops in 5%. No seasonal or geographic basis for this variation was found. Identification. Fahay and Obenchain (1978) identified the larvae of Letharchus velifer based on a comparison of myomere and vertebral numbers between larvae and adults and on the distribution of the larvae. Leiby (1984b) verified the identification based on gill arch and caudal osteology, number of branchiostegal rays and the presence of four supraorbital pores in the cephalic lateralis system. Distribution (Fig. 859). Letharchus velifer larvae are known from North Carolina to Florida, the Florida Straits, and the northeastern Gulf of Mexico. Study Material 204 specimens 7-78 mm. ATLANTIC OCEAN: South Carolina: SCMRI0574253 (1,12), 0574252 (3, 8-10). Georgia: FDNR 11617L (1,19). Florida: FDNR 11595L (3,8-14), 11593L (1,13). FLORIDA STRAITS: FDNR 11596L (1, 22), 17007L (1, 72), 11594L

Ophichthid Leptocephali

889

B

UV 1

UV 2 & GB

DFO

FIGURE 860. Letharchus velifer: A. FDNR 17010L, 7 mm SL newly hatched engyodontic stage with yolk. B. FDNR 11593L, 13 mm SL engyodontic stage. C FDNR 11604L, 58 mm SL euryodontic stage. D. FDNR 11611L, 67 mm SL metamorphic stage. E, F. ANSP 156655, 56 mm SL euryodontic stage.

(1,11), 11618L (1,50). GULF OF MEXICO: Florida: FDNR 17010L (1, 7), 17008L (1, 52), 17009L (3, 45-53). ANSP 156655 (1, 56). FDNR-SML 15889-001 (2, 53-58), 15888001 (1,51), 15883-000 (1,52), 15884-000 (5,35-51), 15854001 (2, 44-59), 15882-000 (1, 69), 15855-002 (2, 41-43). FDNR 11604L (1, 58), 11613L (2, 68-78), 11614L (4, 42-

66), 11597L (17, 34-65), 11598L (3,11-24), 11605L (3,1425), 11607L (1, 12), 11608L (1, 18), 11610L (3, 40-50), 11606L (85, 25-69), 11609L (39, 19-66). Alabama: FDNR 11612L (1, 15), 11616L (1, 26), 11602L (1, 70), 11603L (1, 71), 11611L (1, 67), 11615L (2, 23-49), 11599L (1, 64), 11600L (3, 47-59), 11601L (1, 55).

Fishes of the Western North Atlantic, Part 9

890

Uv

1

LIV 2 & GB

LIV 1

FIGURE 861. Callechelys bilinearis: A. ANSP 156616,6 mm SL engyodontic stage. B. ANSP 156620,38 mm SL euryodontic stage, C, D. ANSP 156621, 53 mm SL euryodontic stage.

Callechelys bilinearis Kanazawa, 1952 Figures 861, 862, Tables 87, 104, 106 ILeptocephalus caribbaeus Fowler, 1944: 130, 163, fig. 49 (original description, Old Providence Island, Caribbean, holotype ANSP 70121). Castle, 1969c: 36 (compiled, tentatively referred to Ophichthidae). Fahay and Obenchain, 1978: 474 (referred to Apterichtus). Leiby, 1984b: 422 (referred to Callechelys sp.). Callechelys bilinearis. Leiby, 1984b: 407, figs. 11-13 (descr., Gulf of Mexico, Bahamas, Yucatan Straits).

Distinctive Characters. Seven pronounced gut loops; dorsal-fin origin anterior to myomere 17; little or no pigment at midline anterior to anus; round pigment patches in body wall on tail and lateral to gut loops; more than 150 total and 90 nephric myomeres. Description. Total myomeres 158-166; nephric

myomeres 94-100; preanal myomeres 97-102; predorsal myomeres 10-15 (Tables 104,106). Dorsal-fin rays 487 (n = 1); anal-fin rays 160-197 (n = 7, x = 177.7). Dorsal-fin origin above or anterior to level of first liver lobe. Branchiostegal rays 28 (n = 3). Basibranchial 2 present; basibranchials 3-4 absent; hypobranchial 4 present, free from reduced ceratobranchial 5. Two hypurals supported by IVi terminal centra. Seven pronounced gut loops; nephros terminates on last gut loop, 1-4 myomeres anterior to anus. Pigmentation. No head pigment in engyodontic stage. By mid-euryodontic stage head pigment consists of small scattered spots on upper jaw near base of teeth; group of spots on side of head lateral to medulla; a few melanophores occasionally ventral to throat.

Ophichthid Leptocephali

891

TABLE 106. Frequency distribution of myomere counts of Callechelys bilinearis and Callechelys guineensis leptocephali. Total

158 159 160 161 162 163 164 165 166 ... 174 175 176 177 178 179 180 181 182 183 184 bilinearis guineensis

1

1 4

1

2

1

2

-

1

-

1

-

1

Nephric bilinearis guineensis

94

95

96

97

98

99 100 ... Ill 112 113 114 115 116 117 118 119 120

1

4

1

2

5

6

3 1

2

1

5

4

1

-

1

1

1

Preanal bilinearis guineensis

97

98

99 100 101 102 , . . 112 113 114 115 116 117 118 119 120 121

3

3

2

4

7

3 1

—

3

3

1

5

2

1

—

1

Predorsal bilinearis guineensis

6

7

8

9

10

11

12

13

14

15

4

1

1

2

1 1

3

4

4

2

1

Midline pigment in engyodontic stage limited to 1-2 subcutaneous spots on tail just ventral to notochord; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. By euryodontic stage midline pigment consists of spots or streaks on a few postanal myosepta, rarely any preanal myosepta pigmented; 3 pronounced, round patches in body wall on tail lateral to 3 pronounced, round subcutaneous patches just ventral to notochord; some pigment still at tail tip. Ventral margin pigment consists of a few melanophores occasionally in body wall near pectoral-fin base; patches on dorsal surface of each gut loop; pronounced, round patches in body wall lateral to each gut loop. No pigment patches between gut loops; few, if any, anal-fin pterygiophores pigmented. Size. Engyodontic stage specimens examined were 6-10 mm; euryodontic stage specimens were 28-103 mm; metamorphic stage specimens were 73-104 mm. Identification. Leiby (1984b) identified the larvae of C bilinearis based on the agreement of

larval and adult meristics, and based on the striking similarity of the larvae to the larvae of the closely related species C. muraena and C. cliffi. Remarks. Fowler (1944) described a species of leptocephalus from the Caribbean based on seven specimens which he called Leptocephalus caribbeaus. In the same volume (p. 163) he listed an additional three specimens collected at Albuquerque Key which he also identified as L. caribbaeus although he did not list them as paratypes and he did not list catalog numbers for them. The myomere counts he listed for the holotype (total 129, preanal 74) do not agree with his illustration which has 136 total and 80 preanal, and do not agree with the specimen under that catalog number which has 164 total and 101 preanal. He did not give myomere counts for any of the other specimens, but the specimens catalogued under the numbers he listed (ANSP 70122-70127) and three specimens from Albuquerque Key (ANSP 70128-70130) have a total myomere range of 159-166 and a preanal myomere range of 98-102. Fowler indicated that the holotype was 105 mm, that the size range of the

Fishes of the Western North Atlantic, Part 9

892

63). PUERTO RICO: FDNR 17515L (2, 70-74). PROVIDENCIA: ANSP 70128-70130 (3, 83-104), 70121 (1,102), 70122-70127 (6, 84-103), 156619 (2, 28-65), 156620 (1, 38), 156621 (2, 51-53), 156622 (1, 43). YUCATAN STRAITS: ANSP 156623 (1, 54), 156624 (1, 73).

Callechelys guineensis (Osorio, 1894) Figures 862, 863, Tables 87, 104, 106 Callechelys perryae. Leiby, 1984b: 407, figs. 14-17 (descr., Gulf of Mexico, Yucatan Straits).

85*

70*

55*

FIGURE 862. Distribution of Callechelys bilinearis and Callechelys guineensis larvae based on material examined.

paratypes was 86-102 mm, and that the specimens from Albuquerque Key were 84-108 mm. The specimen in ANSP 70121 is currently 102 mm, the paratypes are 84-103 mm, and the specimens from Albuquerque Key are 83-104 mm. Fowler indicated that the holotype had four spots "infra-axially on tail." His drawing of the specimen shows three spots, and all ten catalogued specimens have three. Shrinkage or differences in measurement technique could readily account for the differences between the sizes listed by Fowler and the current lengths of the catalogued specimens, but the discrepancies between Fowler's description, his illustration and the actual condition of the catalogued specimens cannot unequivocally be resolved. If the specimen in ANSP 70121 is the holotype, and if this series of larvae is correctly attributed to C. bilinearis, then caribbaeus is the senior synonym of bilinearis. However, because of the discrepancies L caribbaeus is considered a nomen dubium and the name C. bilinearis is retained for the adults. Distribution (Fig. 862). Callechelys bilinearis larvae are known from the Gulf of Mexico, the Bahamas, the Caribbean, and the Yucatan Straits. Study Material. 26 specimens 6-104 mm. GULF OF MEXICO: FDNR11656L (1,56). ANSP 156616 (3, 6-10). BAHAMAS: ANSP 156617 (1, 67), 156618 (1,

Distinctive Characters. Eleven moderate gut loops; dorsal-fin origin anterior to myomere 13; pigment on side of head lateral to medulla; round or saddle-shaped patches of pigment on ventral margin of tail; more than 107 nephric myomeres. Description. Total myomeres 174-184; nephric myomeres 111-120; preanal myomeres 112-121; predorsal myomeres 6-10 (Tables 104,106). Dorsal-fin rays 641 (n = 1); anal-fin rays 231-240 (n = 2). Dorsal-fin origin midway between neurocranium and level of first liver lobe. Basibranchial 2 present; basibranchial 3 reduced or absent; basibranchial 4 present; hy pobranchial 4 present, united with a reduced ceratobranchial 5. Two hypurals supported by a terminal half centrum. Eleven moderate gut loops; nephros terminates on last gut loop, 0-3 myomeres anterior to anus. Pigmentation. No head pigment in early engyodontic stage larvae. By mid-euryodontic stage head pigment consists of a few spots occasionally at base of teeth on upper jaw; several small patches on side of head lateral to medulla; a few stellate melanophores on side of head lateral to notochord and occipital arch; subcutaneous pigment ventral to notochord at chondrocranium; some pigment ventral to throat. Midline pigment in early engyodontic stage larvae limited to one subcutaneous pigment patch on tail just ventral to notochord which reaches ventral margin of myomeres; pigment on dorsal surface of nerve cord and ventral surface of notochord at tail tip. By mid-euryodontic stage midline pigment consists of dark streaks on every 5th-llth myoseptum; pigment in body wall adjacent to pigmented myosepta; pigment on dorsal surface of notochord medial to pigmented myo-

Ophichthid Leptocephali

893

B

UV 1

FIGURE 863. Callechelys guineensis: A. FDNR 11586L, 19 mm SL engyodontic stage. B-D. ANSP 156629, 66 mm SL euryodontic stage.

septa; 4 subcutaneous patches on tail just ventral to notochord. Ventral margin pigment in early engyodontic stage consists of patch on dorsal surface of esophagus and in body wall near pectoral-fin base; pigment on dorsal surface of gut at each gut loop. By mid-euryodontic stage ventral margin pigment increases to include one or more patches on dorsal surface of gut midway between each gut loop; small patch on surface of gut beneath urinary bladder near anus; pigment in body wall lateral to each gut loop; patches of frequently stellate melanophores in body wall ventral and ventrolateral to esophagus and liver lobes; occasionally a few patches ventral to gut posterior to liver lobes; round or saddle-shaped patches of pigment in body wall on ventral margin of tail, frequently extending onto anal-fin pterygiophores; some anal-fin pterygiophores pigmented between body wall patches. Size. One 12 mm engyodontic stage specimen still had a little yolk under its gut. Specimens at

hatching may be as large as 6-7 mm. The largest engyodontic stage specimen examined was 23 mm. Euryodontic stage specimens were 25-82 mm. Maximum size probably exceeds 90 mm. Identification. Leiby (1984b) identified the larvae of Callechelys guineensis (= C. perryae, Storey) using a combination of gill arch and caudal osteology, dorsal-fin position, and the number of total and nephric myomeres. Distribution (Fig. 862). Callechelys guineensis larvae are known from north of Bermuda, the Gulf of Mexico and the Yucatan Straits. Study Material 17 specimens 12-82 mm. ATLANTIC OCEAN: MCZ 61615 (1, 82), 38°16'N, 66°32'W, 30-31 July 1976. GULF OF MEXICO: Florida: FDNR 16999L (1,49), 25°00'N, 83°10'W, Nov. 1973. FDNR 17000L (1,12), 26°00'N, 82°14'W/ Nov. 1972. FDNR 11592L (1, 28), 28°43'N/ 84°54'W/ 8 Sept. 1969. FDNR 11587L (I/ 69), 28°43'N, 85°54'W, 7 July 1969. FDNR 11586L (1,19), 29°09'N, 85°05'W, 6 July 1969. FDNR 11590L (1, 21), 29°17'N/ 85°40'W, 10 Aug. 1969. FDNR 11588L (2, 3650), 29°55'N/ 85°55'W, 6 Aug. 1969. FDNR 11589L (2,1415), 29°55'N/ 85°55'W, 6 Aug. 1969. FDNR 11591L (1, 55),

Fishes of the Western North Atlantic, Part 9

894

UV 1 LIV 2 & GB

B 1

UV 2 & GB

DFO

D

UV 1

FIGURE 864. Callechelys muraena: A. FDNR 11584L, 10 mm SL engyodontic stage. B. FDNR 11573L, 40 mm SL euryodontic stage. C, D. ANSP 156627, 50 mm SL euryodontic stage.

29°55'N, 85°55'W, 10 Oct. 1969. Mexico: ANSP 156628 (2, 17-23), 23°03'N, 90°57'W, 17 Feb. 1977. YUCATAN STRAITS: ANSP 156629 (1, 66), 21°34'N, 85°56'W, 15 Feb. 1977. ANSP 156630 (1,25), 22°16'N, 88°55'W, 9 Nov. 1975. OTHER: ANSP 156339 (1,74), label disintegrated in vial, no data available.

Callechelys muraena Jordan and Evermann, 1887 Figures 864, 865, Tables 87,104, 107 Apterichtus k end alii (not Sphagebranchus k end alii Gilbert). Fahay and Obenchain, 1978: 476, fig. 31 (descr., Georgia to North Carolina). Leiby, 1981: 69 (suggested that Fahay and Obenchain's specimens were Callechelys muraena). Apterichtus ansp (not Verma ansp Bohlke). Fahay and Obenchain, 1978: 475, fig. 30 (descr., South Carolina). Leiby, 1981:69 (suggested that Fahay and Obenchain's specimen was probably an undescribed species of Callechelyini).

Callechelys muraena. Leiby, 1984b: 404, figs. 6-10 (descr., Georgia, Florida Straits, Gulf of Mexico, Bahamas, Yucatan Channel).

Distinctive Characters. Seven pronounced gut loops; little or no midline pigment anterior to anus; round pigment patches in body wall on tail and lateral to gut loops; less than 151 total and 91 nephric myomeres. Description. Total myomeres 138-148; nephric myomeres 81-88; preanal myomeres 82-89; predorsal myomeres 9-16 (Tables 104,107). Dorsalfin rays 468 (n = 1); anal-fin rays 147-203 (n = 9, x = 175.7). Dorsal-fin origin above first liver lobe. Branchiostegal rays 23-26 (n = 4, x = 24.0). Gill arch and caudal osteology as in C. bilinearis. Seven pronounced gut loops; nephros terminates on last gut loop, 0-3 myomeres anterior to anus. Pigmentation. Essentially as in Callechelys bilinearis.

Ophichthid Leptocephali

895

TABLE 107. Frequency distribution of myomere counts of Callechelys muraena and Callechelyini sp. Total Callechelys muraena Callechelyini sp.

138

139

140

1

3

2

141 142

4

8

143

144

4

1

145

24

146

4

147 148

2

149

150 151 152

153 154

2

Nephric Callechelys muraena Callechelyini sp.

81

82

83

84

85

86

87

88

2

5

7

12

15

17

3

2

...

102 103 104 105 106 107 108 109 1

3

—

2

-

-

-

1

Preanal Callechelys muraena Callechelyini sp.

82

83

84

85

86

87

88

89

3

3

7

10

22

8

8

3

...

103 104 105 106 107 108 109 110

1

2

1

1

1

— -

1

Predorsal Callechelys muraena Callechelyini sp.

9

10

11

12

13

14

15

16

2

1

3 1

10 —

5 1

10

3

2

Size. The largest engyodontic stage specimen examined was 20 mm. Euryodontic stage specimens were 22-68 mm; metamorphic stage specimens were 55-72 mm. Identification. Leiby (1984b) identified the larvae of Callechelys muraena based on dorsal-fin origin, condition of the cephalic lateralis system, number of branchiostegal rays, gill arch and caudal osteology, number of nephric myomeres, and number of total myomeres. Leiby (1984b) referred a specimen with 127 total and 86 preanal myomeres identified by Fahay and Obenchain (1978) as Apterichtus ansp to Callechelys sp. because the total myomere count was lower than any known adult Callechelys, but its seven pronounced gut loops and pigmentation pattern were so similar to that of C. bilinearis and C. muraena that I had no doubt it was a Callechelys. Like Fahay and Obenchain, I felt at that time that their specimen was the second specimen of Leptocephalus caribbaeus, Fowler. I now have little doubt, however, that their specimen is a Callechelys muraena which lost part of its tail and which regenerated a caudal structure, a situation not uncommon in leptocephali.

Leiby (1984b) erroneously referred a series of four larvae which Blache (1977) identified as Verma kendalli to Callechelys muraena. Blache's larvae have nine pronounced gut loops and four round tail spots. They are undoubtedly a species of Callechelys, but they are clearly not C. muraena. Distribution (Fig. 865). Callechelys muraena larvae are known from the Scotian Shelf to the Bahamas, the Atlantic seaboard of the U.S. from North Carolina to Georgia, the Florida Straits, eastern Gulf of Mexico, and the Yucatan Straits. Study Material 76 specimens 7-72 mm. ATLANTIC OCEAN: Scotian Shelf to Bahamas: ARC 8600973 (1, 58), 8600998 (1,49). MCZ 61605 (1, 55), 61606 (2, 54-55), 61607 (1, 45+, tail broken), 61608 (2, 52-56), 61609 (1, 27), 61610 (3, 62-67), 61611 (1, 49), 61612 (1, 35). ANSP 156625 (1, 52), 156626 (1,56). North Carolina to Georgia: MCZ 61613 (2, 42-54), 61614 (1, 66). FDNR 11584L (15, 7-24), 11585L (1, 13). FLORIDA STRAITS: FDNR 11657L (1,47), 11658L (1, 38). GULF OF MEXICO: Florida: FDNR-SML 1082-000 (1, 41). FDNR 11573L (3, 25-40), 11574L (1, 25), 11580L (1, 68), 11571L (1, 41), 11572L (2,13-20), 11578L (1, 58), 11570L (1, 31), 11579L (1, 56), 11566L (2, 9-11), 11567L (12, 12-26), 11575L (1, 15), 11583L (1, 32), 11576L (1,41), 11568L (1, 38), 11581L (1, 27), 11569L (3, 8-10). Alabama: FDNR 11582L (1, 27),

896

Fishes of the Western North Atlantic, Part 9

FIGURE 865. Distribution of Callechelys muraena and Callechelyini sp. larvae based on material examined. 11577L (2, 15). YUCATAN STRAITS: ANSP 156627 (1, 50). FDNR 16998L (1, 72).

Callechelyini species Figures 865, 866, Tables 104,107 Callechelyini genus and species unknown. Leiby, 1984b: 417, figs. 28-29 (descr., Florida Straits, Gulf of Mexico).

Distinctive Characters. Ten moderate to pronounced gut loops; dorsal-fin origin anterior to myomere 15; pigment on side of head lateral to notochord and occipital arch; round or saddleshaped pigment patches in body wall on ventral tail margin; dorsal margin pigment occasionally present on tail. Description. Total myomeres 148-154; nephric myomeres 102-109; preanal myomeres 103-110; predorsal myomeres 11-13 (Tables 104,107). Analfin rays 172 (n = 1). Dorsal-fin origin above or just anterior to level of first liver lobe. Basibranchial 2 and 4 absent; basibranchial 3 present; hypobranchial 4 present; ceratobranchial 5 absent. Three hypurals, probably supported by a terminal half centrum. Ten moderate to pronounced gut loops, nephros terminates on last gut loop, 0-2 myomeres anterior to anus. 'Pigmentation. Head pigment consists of a few spots at base of teeth on anterior portion of upper

jaw; a few occasionally stellate melanophores on side of head lateral to notochord and occipital arch; occasionally a few spots ventral to throat. No dorsal margin pigment in early euryodontic stage. By mid-euryodontic stage dorsal margin pigment consists of 4-5 small patches on dorsal margin of tail, extending slightly onto fin membranes; number of patches may increase with size and may extend more anteriorly. Midline pigment occurs approximately every 10th myomere and consists of dark streaks on myosepta; occasionally stellate melanophores in body wall adjacent to pigmented myosepta; pigment on dorsal surface of notochord medial to pigmented myosepta; 4 subcutaneous patches on tail just ventral to notochord; pigment in body wall lateral to subcutaneous tail patches. Ventral margin pigment consists of patch on esophagus near pectoral-fin base; pronounced patch on dorsal surface of each gut loop; smaller patch on dorsal surface of gut generally midway between each gut loop; occasionally round patches of body wall pigment lateral to each gut loop; pigment in body wall ventral to midpoint of esophagus and ventral or ventrolateral to liver lobes; 5-6 (possibly more in larger larvae) round or saddle-shaped patches in body wall on ventral tail margin, occasionally extending onto fin membrane and pterygiophores. Size. Euryodontic stage specimens were 21-47 mm. Identification. Identification of these leptocephali to tribe is ambiguous. Leiby (1984b) tentatively placed these larvae in the tribe Callechelyini based on dorsal-fin origin, the presence of hypobranchial 4, gut morphology and pigmentation. He had reservations about this placement because the larvae have three hypurals, a condition not found in any other Callechelyini except the species which he had provisionally identified as Callechelys sp. cf. springeri and which now has been tentatively reidentified as Gordiichthys randalli. No new data have become available which make it possible to unambiguously identify these larvae to tribe; consequently, these leptocephali are provisionally being retained in

Ophichthid Leptocephali

/

UV 1

B

897

UV 2 & GB

DFO

UV 1

FIGURE 866. Callechelyini sp.: A. ANSP 156652, 21 mm SL euryodontic stage. B-D. ANSP 156653, 47 mm SL euryodontic stage.

the Callechelyini based on the presence of hypobranchial four and the nature of their pigmentation, but it is possible they are an undescribed bascanichthyin. No known Atlantic Callechelyini or Bascanichthyini have meristics consistent with those of these larvae. The gill arch osteology of the one cleared and stained specimen is unique to this species (Fig. 855) and possibly is anomalous. These larvae cannot currently be assigned to genus. Distribution (Fig. 865). These larvae are cur-

rently known only from the Florida Straits and Gulf of Mexico. Study Material. Seven specimens 21-47 mm. FLORIDA STRAITS: ANSP 156650 (1, 28), 24°44'N, 82°57'W, 7 Mar. 1970. GULF OF MEXICO: Florida: FDNR 11629L (1, 23), 26°24'N, 82°58'W/ 12 Nov. 1965. FDNR 11628L (1, 39), 28°46'N/ 84°37'W, 12 Aug. 1969. Mexico: ANSP 156651 (1, 36), 20°54'N, 93°10'W, 11 Nov. 1975. ANSP 156652 (1, 21), 20°53'N, 93°10'W, 11 Nov. 1975. ANSP 156653 (1, 47), 20°51'N, 92°58'W/ 19 Feb. 1977. ANSP 156654 (1, 46), ?location, ?date.

Family Anguillidae: Leptocephali D A V I D G. SMITH

Characters. Moderate to moderately small leptocephali, maximum size approximately 80 mm SL. Body moderately deep, depth about one-fifth SL; tail moderate. Gut simple, without swellings or loops, anus near three-quarters SL; kidney ends slightly behind midpoint of gut. Dorsal fin moderately short, begins slightly before level of anus. Head and snout moderately short. No melanophores on head or body.

Composition. The Anguillidae contains a single genus, Anguilla Schrank, and some 15 species. The leptocephali are essentially identical except for certain meristic and morphometric characters. Leptocephali of two species are found in the western North Atlantic: the American eel, Anguilla rostrata, and the European eel, Anguilla anguilla. They are distinguished only by the number of myomeres.

KEY TO THE ANGUILLID LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC 1. Myomeres ca 103-111 2. Myomeres ca 112-119

Anguilla rostrata, p. 898 Anguilla anguilla, p. 899

85 (13), predorsal 65-70 (5), head 8-14 (13), greatest depth 16-23 (13). Size. The largest specimen recorded is 70 mm TL (Kleckner and McCleave, 1985: 72). Identification. The leptocephalus of the American eel was first recognized by its close resemblance to that of the European eel; its myomere count matches the vertebral count of adult Anguilla rostrata. Spawning and Growth. The life history of Anguilla rostrata is discussed in detail elsewhere (see Family Anguillidae). Distribution. Leptocephali of Anguilla rostrata are found predominantly in an area bounded by the Antilles on the south, the North American continent on the west, and Newfoundland on the north. They have been collected in the Northern Caribbean, the Yucatan Channel and the eastern Gulf of Mexico (Kleckner and McCleave, 1985; Eldred, 1971; this study), but not in great

Anguilla rostrata (Lesueur, 1817) Figure 867 LeptocephalusgrassiiEigenmannand Kennedy, 1902: 84,

fig.i.

Anguilla chrysypa. Eigenmann and Kennedy, 1902: 84. Anguilla rostrata. Schmidt, 1916a: 6; 1922: 200, pi. 17, fig. 1, pi. 18. Taning, 1938. Jespersen, 1942: 10. Eldred, 1968d; 1971. Smith, 1968. Comparini and Rodino, 1980. Comparini and Schoth, 1982. Kleckner and McCleave, 1982. Schoth, 1982. Schoth and Tesch, 1982. Kleckner et al., 1983. Kleckner and McCleave, 1985. Wippelhauser et al., 1985.

Distinctive Characters. Leptocephali of Anguilla rostrata have fewer myomeres than those of A. anguilla (ca 103-111 vs 112-119, respectively). Description (from Jespersen, 1942: 10; Eldred, 1968d and 1971; Smith, 1968: 281). Total myomeres ca 103-111 (n = 563), preanal myomeres 68-73 (12), predorsal myomeres 61-66 (5), LVBV 44-47 (12). Proportions as % of SL: preanal 72898

Anguillid Leptocephali

899

FIGURE 867. Anguilla rostrata: A. ANSP 155889, 10 mm SL, Yucatan Channel. B. MBI 28, 44 mm SL, Yucatan Channel.

numbers. The easternmost record is 49°43'N, 20°45'W (Kleckner and McCleave, 1985: 73). Study Material 300 specimens, 10-58 mm SL: 273 specimens from Smith (1968), plus the following additional material. BAHAMAS: ANSP 155101 (4, 44-46), 155102 (2, 4245), 155103 (4, 28-40), 155104 (2, 47-50), 155105 (3, 4349). YUCATAN CHANNEL: ANSP 154812 (7, 10-16), 154813 (1, 47), 155889 (2, 10-12), 157617 (1, 48). MBI 28 (1, 44).

Anguilla anguilla (Linnaeus, 1758) Leptocephalus brevirostris Kaup, 1856b: 150, pi. 18, fig. 15 (original description, Messina, holotype MNHN 2901).

Distinctive Characters. Identical to Anguilla rostrata but more myomeres (112-119). Description. Total myomeres 112-119 (n = 472) (Jespersen, 1942: 10). Size. Maximum size about 80 mm SL. Identification. The leptocephalus of Anguilla anguilla was identified by Grassi and Calandruccio from metamorphosing specimens (Grassi, 1896). Spawning and Growth. Anguilla anguilla spawns

in the Sargasso Sea somewhat to the east of the spawning ground of A. rostrata, although the two areas overlap. Spawning occurs in the spring, primarily March-June. Schmidt (1922) proposed that A. anguilla requires 3 years to complete its larval development, but Boetius and Harding (1985: 147, 156) have recently questioned this. They suggest that the two species of Anguilla grow at the same rate and that A. anguilla metamorphoses after 12-15 months. The matter needs further study. Distribution. Leptocephali of Anguilla anguilla co-occur over much of the western Atlantic with those of A. rostrata, but they are more common to the east. Schmidt (1922: 202) found that west of about 62°W and south of 24°N leptocephali of A. rostrata predominated; north and east of those lines, leptocephali were mainly A. anguilla. The westernmost records of A. anguilla are three specimens from North American continental slope water (Kleckner and McCleave, 1985: 75, 88). Study Material. 15 specimens, 30-43 mm SL (Smith, 1968: 287).

Family Muraenidae: Leptocephali DAVID G. SMITH In Monopenchelys acuta, the anus is near midbody, and the anal fin begins immediately behind it. The dorsal fin, however, originates a substantial distance behind the level of the anus. The remaining muraenid leptocephali all have the dorsal fin originating over or before the anus. The leptocephalus tentatively assigned to Gymnothorax miliaris lacks intestinal pigment. The remainder have some form of pigment on the gut and constitute the largest group of muraenid leptocephali. The last-mentioned group can be further subdivided, at least in the western Atlantic, into two subgroups. One of these has a relatively long gut with the anus at about the third quarter of the standard length. The dorsal fin begins some 60 myomeres before this point near the first quarter of the standard length. Included here is the leptocephalus of Gymnothorax ocellatus and its close allies. In the other subgroup the anus is near midbody, and the dorsal fin begins over or slightly before that point, by a distance of 35 myomeres or less. One member of this subgroup is identified with some confidence as Gymnothorax moringa and another, with somewhat less confidence, as G. vicinus. Leptocephali of at least five other species are known in this subgroup, but they cannot be identified with an adult. No leptocephali are known that can be conclusively identified with Echidna, Enchelycore, or Muraena.

Characters. Small to moderate-sized leptocephali, maximum SL generally less than 100 mm. Body moderate to moderately deep, depth about one-sixth to one-seventh SL; tail broadly rounded. Gut a simple, narrow tube without loops or thickenings; anus at about a half to three-quarters SL. Origin of dorsal fin variable, from near first quarter of SL to shortly before end of tail. Pectoral fin reduced. Head and snout usually short and blunt; posterior nostril, when developed, near level of upper margin of eye. Pigmentation variable, when present consists of small melanophores on gut, dorsal midline, head, base of fin rays, or subcutaneously on underside of dorsal nerve cord. Western Atlantic species lack superficial lateral pigment. Composition. The Muraenidae is a fairly homogeneous group whose leptocephali show little fundamental variation. Genera and species groups are characterized mainly by pigmentation and fin position. Larvae of Anarchias and Uropterygius are unique among leptocephali in having the origin of the anal fin distant from the anus. In both genera the dorsal and anal fins are restricted to the posterior extremity of the body, reflecting the condition in the adults. Anarchias is further characterized by the near or total lack of pigment. The leptocephalus of Channomuraena also has the vertical fins restricted to the posterior end of the body, but the gut is longer and reaches the base of the anal fin.

KEY TO THE MURAENID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC la. Dorsal and anal fins restricted to posterior extremity of body; anal fin distant from anus . 2 Ib. Anal fin begins immediately behind anus; dorsal and anal fins usually begin well before tail tip 3 900

Muraenid Leptocephali

901

2a. One to three small melanophores near base of brain; no other pigment; myomeres 105-114 Anarchias similis, p. 901 2b. Melanophores on bottom of gut, on dorsal midline, and on top of head; myomeres 118-123 Uropterygius macularius, p. 903 3a. Fewer than 30 myomeres between origin of dorsal fin and tip of tail Channomuraena vittata, p. 904 3b. More than 50 myomeres between origin of dorsal fin and tip of tail 4 Monopenchelys acuta, p. 905 4a. Dorsal fin begins behind level of anus 4b. Dorsal fin begins over or before anus 5 5a. No pigment on intestine; an ill-defined band through eye formed by an elongate group of melanophores behind and before eye (?)Gymnothorax miliaris, p. 906 5b. Pigment present on intestine; no band through eye 6 6a. Sixty or more myomeres between origin of dorsal fin and anus 7 6b. Approximately 35 or fewer myomeres between origin of dorsal fin and anus 8 Gymnothorax ocellatus complex, p. 907 7a. Myomeres 136-150 7b. Myomeres ca 167 Gymnothorax conspersus, p. 909 8a. A single complete row of melanophores on ventral midline of esophagus between heart and liver (Fig. 875A) 9 8b. Pigment on ventral midline of esophagus in a double row or incomplete (Fig. 875B, C ) . . . . 11 9a. No pigment on palate; total myomeres 137-143; preanal myomeres 66-74 Gymnothorax moringa, p. 910 9b. Pigment present on palate 10 lOa. Total myomeres 142-148; preanal myomeres 71-76 Gymnothorax sp. A, p. 913 lOb. Total myomeres 139-142; preanal myomeres 79-81 Gymnothorax sp. B, p. 914 lla. A double row of melanophores on ventral midline of esophagus (Fig. 875C) Gymnothorax sp. C, p. 914 lib. Pigment on ventral midline of esophagus incomplete (Fig. 875B) 12 12a. Preanal myomeres 60-68 Gymnothorax vicinus, p. 912 12b. Preanal myomeres 75-77 13 13a. Predorsal myomeres 54-57; total myomeres 131-136 Gymnothorax sp. D, p. 915 13b. Predorsal myomeres 40; total myomeres 136-140 Gymnothorax sp. E, p. 915 Anarchias similis (Lea, 1913) Figure 868 Leptocephalus similis Lea, 1913: 32, figs. 23-24, pi. 4, figs. 5-6. Anguilla rostrata (not of Lesueur, 1817). Fish, 1927: 289. Anarchias yoshiae. Eldred, 1968e. Karmovskaya, 1975: 96. Keller, 1976: 107. Blache, 1971b: 208, figs. 4-6; 1977: 21, figs. 4a-5. Smith, 1979: 19, fig. 26.

Distinctive Characters. Dorsal and anal fins restricted to posterior extremity of body, anal fin distant from anus; no pigment except 1-3 small melanophores near base of brain; 105-114 myomeres. Description. Total myomeres 105-114 (n = 92),

preanal myomeres 52-59 (92), predorsal myomeres 96-104 (40), LVBV 53-57 (28). Proportions as % of SL: Preanal 50-77 (43), HL 6-14 (45), greatest depth 12-23 (43). Body moderately short, anus slightly behind midlength. Vertical fins confined to posterior extremity of body, anal fin distant from anus. Pigmentation. One to three small melanophores internally near base of brain. Indistinct dark spots internally below spinal cord. No other pigment. Size. Maximum size 50-60 mm SL. Variation. Blache (1971b: 209, figs. 3-4; 1977: 21, fig. 5) described and illustrated a paired row

Fishes of the Western North Atlantic, Part 9

FIGURE 868. Anarchias similis (B, C from Smith, 1979: fig. 26): A. ANSP 155886, 43 mm SL. B. ANSP 155924, 40 mm SL; head. C Same; tail.

of small melanophores below the intestine and an unpaired series along the ventral margin of the body from the anus to the tail. This pigment was not present in any of the western Atlantic specimens examined here, nor was it mentioned by Eldred (1968e). Blache's specimens furthermore lacked the deep pigment near the base of the brain and below the spinal cord, and they had fewer dorsal- and anal-fin rays (5-10 and 48, respectively) than Eldred's (26-41 and 14-20). These are substantial differences and suggest a significant genetic divergence between the eastern and western Atlantic populations of this nominal species. Identification. Eldred (1968e) identified this leptocephalus through metamorphosing specimens. Spawning and Growth. There is no clear seasonal pattern to the size distribution of the leptocephali. In the Yucatan Channel, specimens smaller than 10 mm SL were collected in both July-August and November, and specimens smaller than 20 mm were collected in February and April. The maximum size of the leptocephali was about the same in all seasons (46-56 mm SL).

The greater abundance of leptocephali in summer and fall suggests that spawning is heaviest in the summer and decreases in intensity through fall to reach a minimum in winter and spring. Keller (1976:116) found a similar pattern around Bermuda. Remarks. Of all the leptocephali collected during the MBI cruises, Anarchias similis was the species that most often came up alive in the nets. Distribution. This leptocephalus is widely distributed throughout the western Atlantic, including the Caribbean, the Gulf of Mexico, the Straits of Florida, the Bahamas, Bermuda, and the Sargasso Sea. More than most muraenid leptocephali, it is commonly found in the open Atlantic far from land. Keller (1976: 108) recorded 190 specimens of Anarchias similis from the Bermuda Ocean Acre compared to 64 specimens of all other moray species combined. In the Sargasso Sea in 1979, the preponderance was even greater: 179 specimens of A. similis and only six specimens of other muraenid species. Lea's types were taken in the central Atlantic at 34°44'N, 47°52rW. This pattern of distribution suggests that the

Muraenid Leptocephali

903

FIGURE 869. Uropterygius macularius: ANSP 155893, 37 mm SL.

adults may travel to the Bermuda-Sargasso area to spawn. If so, they would be among the few muraenid species that show evidence of spawning migrations. Study Material. 564 specimens, 6-56 mm SL. CENTRAL ATLANTIC: UMML 402-7T1-D (1, 46). SARGASSO SEA: ISH Anton Dohrn 5527 IK-1 (1, 38), 5538 IK-2 (6, 40-49), 5562 IK-4 (2, 37-38), 5576 IK-5 (9, 38-44), 5588 IK-6 (5, 34-43), 5588 MOC 6-6 (1, 44), 5596 IK-7 (6, 41-49), 5603 IK-8 (13, 36-48), 5610 IK-9 (15, 4152), 5615 IK-10 (6, 44-50), 5623 IK-12 (2, 43-47), 5632 MT-11 (1, 53), 5638 IK-15 (2, 35-42), 5643 IK-16 (16, 3846), 5653 IK-17 (5, 41-48), 5666 IK-19 (12, 40-48), 5674 IK-21 (16, 37-45), 5684 IK-23 (19, 37-48), 5684 MOC 137 (2, 42-44), 5688 IK-24 (1, 38), 5688 MOC 14-4 (2, 4344), 5689IK-25 (5,44-51), 5695IK-26 (3,37-42), 5709IK29 (1, 48), 5717IK-31 (1, 43), 5721IK-32) (1, 40), 5725 IK33 (1, 49), 5738 IK-36 (2, 42-44), 5743 MOC 23-0 (1, 36), 6746IK-39 (7, 40-46), 5750 IK-40 (10, 41-45), 5756 IK-41 (1,41), 5761 MOC 25-0 (4,40-41). UMML Pillsbury 1371 (1, 35). BERMUDA: UMML Pillsbury 1036 (3), 1049 (3, 40-44), 1050 (1, 34). BERMUDA-BAHAMAS: UMML Pillsbury 155 (1,37), 1067 (1,42), 1085 (2, 37-49). UMML 606-8-T1-C + D (1, 37) 606-8-T3-C + D (1, 41). BAHAMAS: ANSP 155066 (1,36), 155168 (1,13), 155169 (1,10), 155170 (1, 9), 155171 (3, 5-9). UMML Gerda 195 (2, 2430). UMML Pillsbury 191 (1, 47), 1117 (1, 23). UMML Gilliss 1-C (1, 29), 2-A (1, 37). UMML Sands 7 A (1, 35). GULF STREAM: UMML Pillsbury 107 (17,7-29). STRAITS OF FLORIDA: UMML Gerda 8 (1, 42), 46 (1, 38), (17 (2, 40-44), 71 (1, 45), 285 (1, 37), 331 (1, 33), 333 (1, 23), 345 (1,24), 351 (10,24-34). UMML Tursiops 152 (1,25). UMML SL 55 B-3 (1, 24), 58 B-4 (1, 24), 122-2 (1, 29), 122-3 (1, 40). UMML Oregon II 7239-134 (1, 30), 7239-142 (1, 29), 7239-144 (1, 23), 7239-145 (1, 33). GULF OF MEXICO: ANSP 154311 (4, 30-51), 154312 (2, 46-50), 154314 (1, 40), 155146 (1, 36), 155150 (1, 24), 155159 (1, 44), 155160 (1, 52), 155162 (1, 31), 155167 (1, 16), 155886 (2, 42-43). MBI 61 (2, 30-31), 512 (2), 514 (1), 539 (1), 553 (2), 561 (1). UMML 606-7-T1-A (1, 40). YUCATAN CHANNEL: ANSP 154305 (1, 54), 154306 (94,10-56), 154307 (14,1751), 154308 (7, 10-52), 154309 (20, 8-52), 154310 (8, 1252), 154313 (9,13-55), 155137 (3, 15-34), 155138 (2, 29-

35), 155139 (2,51), 155140 (1,22), 155141 (2,19-47), 155142 (4, 16-23), 155143 (2, 39), 155144 (5, 27-41), 155145 (26, 6-50), 155147 (3,18-43), 155148 (2,21-26), 155149 (3,2932), 155151 (1,44), 155152 (2,18), 155153 (2,20-22), 155154 (1, 33), 155155 (5, 18-46), 155156 (6, 18-45), 155157 (3, 23-41), 155158 (2, 28-31), 155161 (2, 42), 155163 (3, 925), 155164 (10,16-28), 155165 (2, 27-50), 155166 (1, 43), 155924 (6, 26-46). MBI 24 (6,17-50), 165 (1), 166 (2), 483487 (6), 490 (2), 493 (1), 502 (1), HISPANIOLA: UMML Pillsbury 1176 (1, 26), 1290 (1, 38). UMML Carib 20 (1, 33). PUERTO RICO DEEP: UMML Pillsbury 1378 (4, 4045). LESSER ANTILLES: UMML Pillsbury 471 (1, 49). VENEZUELA: UMML Pillsbury 462 (1, 20). SOUTHWESTERN CARIBBEAN: UMML Pillsbury 1346 (1, 41). HONDURAS: ANSP 155172 (2, 19-23). NORTHWESTERN CARIBBEAN: UMML Oregon II 7239-61 (1, 22).

Uropterygius macularius (Lesueur, 1825) Figure 869 Leptocephalus juliae Tommasi, 1960: 91, fig. 1. Uropterygius juliae. Eldred, 1968c: 1. Misidentification: Not Uropterygius diopus Bohlke. Blache, 1971b: 212 (Uropterygius wheeleri).

Distinctive Characters. Dorsal and anal fins restricted to posterior extremity of body, anal fin distant from anus; melanophores on dorsal and ventral midline and top of head; myomeres 118123. Description. Total myomeres 118-123 (n = 20), preanal myomeres 71-77 (20), predorsal myomeres 107-114 (14), LVBV 65-67 (6). Proportions as % of SL: preanal 61-74 (23), HL 6-8 (23), greatest depth 10-16 (21). Body moderate, anus near two-thirds SL. Vertical fins confined to posterior extremity of body, anal fin distant from anus. Pigmentation. A series of small melanophores

Fishes of the Western North Atlantic, Part 9

B

FIGURE 870. Channomuraena vittata: ANSP 155072, 35 mm SL.

along bottom of intestine from liver to anus, continuing along ventral midline to anal fin. A series of small melanophores on dorsal midline from approximately the 18th myomere to a point somewhat behind level of anus. Small melanophores superficially on top of head. Internal melanophores at base of brain. A few melanophores between pectoral fin and base of brain. A series of internal melanophores below spinal cord. Size. The largest specimen recorded was 57 mm TL (Eldred, 1968c). The developing sensory pores on the head indicate that the specimen was probably approaching metamorphosis. Identification. Eldred (1968c) identified this leptocephalus through a metamorphosing specimen. Spawning and Growth. Specimens were collected throughout the year. No seasonal pattern of size distribution was apparent. Distribution. Caribbean, eastern Gulf of Mexico, Straits of Florida, Bahamas. Study Material 41 specimens, 15-54 mm SL. BAMAMAS: ANSP 154714 (1, 39), 154715 (2, 29-41), 154717 (1,50), 154720 (2,42-43), 154723 (1,40). STRAITS OF FLORIDA: ANSP 154727 (1,34), 154728 (1,35), 154730 (1, 42). GULF OF MEXICO: ANSP 154729 (1, 30). UMML Oregon II 7020 1-20-1 (1, 40). YUCATAN CHANNEL: ANSP 155028 (1,17), 155029 (1,16), 155866 (1,39), 155867 (2, 27-34), 155868 (1, 31), 155869 (1, 20), 155870 (1, 28), 155871 (2, 15-19), 155872 (1, 32), 155873 (1, 30), 155874

(1, 25), 155875 (1, 28), 155893 (1, 37), 157623 (1, 38). MBI 36 (1, 44). HISPANIOLA: ANSP 154716 (1, 46), 154718 (1, 49), 154719 (1, 46), 154722 (1, 39), 154725 (2, 37-47), 154726 (1,54). COLOMBIA: ANSP 154721 (1,42), 154724 (3, 33-47). EAST-CENTRAL CARIBBEAN: ANSP 154731 (1, 47).

Channomuraena vittata (Richardson, 1844) Figure 870 Channomuraena vittata. Castle, 1970a: 15, fig. 4.

Distinctive Characters. Like Anarchias and Uropterygius, the leptocephalus of Channomuraena has its dorsal and anal fins restricted to the posterior part of the body, although not quite to the same extent. Unlike those two, however, the anal fin of Channomuraena begins immediately behind the anus. The gut of Channomuraena is unusually long, about 80-90% of the standard length. The only other western Atlantic muraenid leptocephali that have a preanal length approaching that value are those of the Gymnothorax ocellatus group, and they have a much longer dorsal fin. Description (including data from Castle, 1970a). Total myomeres 148-159 (n = 5), preanal myomeres 121-127 (4), predorsal myomeres 122 (1), LVBV 110-112 (2), dorsal-fin rays 78-83 (2), analfin rays 65-78 (2), caudal-fin rays 2-3 + 1 (2).

Muraenid Leptocephali

905

FIGURE 871. Monopenchelys acuta: ANSP 155890, 43 mm SL.

Proportions as % of SL: preanal length 81-92 (2), HL 8-9 (2), greatest depth 19-22 (2). Body moderately deep, gut long, anus at about 80-90% SL. Vertical fins confined to posterior part of body, but anal fin begins immediately behind anus; dorsal fin begins almost directly above anus. Pigmentation. A series of minute melanophores is present along the mid-dorsal margin of the body from shortly behind the head to the dorsal fin. A 35-mm specimen (ANSP 155072) has this in a single row, but a 59-mm specimen (MCZ 64889) has a stripe several melanophores in width. The larger specimen also has a series of small melanophores on the ventral margin of the gut, again arranged as a narrow stripe a few melanophores wide. The mid-ventral melanophores are missing in the smaller specimen. Both specimens have a few minute melanophores on the caudal fin. The larger specimen has minute melanophores along the base of the anal fin; the smaller specimen is damaged in this area and whatever pigment it might have had there is lost. Castle (1970a: 15) mentioned only the anal-base pigment in the two specimens he examined, but both were approaching metamorphosis. Size. The two specimens described by Castle (1970a) were 124-125 mm TL and were metamorphosing. The 100-mm specimen examined here was premetamorphic (ANSP 154229). Identification. The adult of Channomuraena vittata is characterized by the posterior position of the anus, at about two-thirds of the standard length. The dorsal and anal fins are confined to the posteriormost part of the body, though to a somewhat lesser extent than those of Anarchias and Uropterygius. There are 118-120 predorsal and 120 preanal vertebrae out of a total of 146154 (Blache, 1967f: 1730; Bohlke, 1982: 40). These

figures all fit the present leptocephalus. Most significantly, only the present leptocephalus has such a high predorsal and preanal count. In the metamorphic specimens described by Castle (1970a) there is no sign of forward movement of the anus or dorsal fin, indicating that they have reached their final position. The close agreement in all these characters led Castle (1970a: 16) to identify the leptocephalus as Channomuraena vittata. Distribution. The six known specimens came from the Bahamas, the northwestern Caribbean, off equatorial Brazil, and near Ascension Island. Study Material. Four specimens, 32-100 mm SL. BAHAMAS: ANSP 155072 (1, 35), 24°59.8'N/ 74°41.4'W/ 150 mwo, R/V Iselin, 9 Sept. 1980. NORTHWESTERN CARIBBEAN: ANSP 157619 (1, 32), 20°41'N, 84°12'W, 02900 m, R/V Alaminos, 9-10 May 1973. EASTERN CARIBBEAN: MCZ 64889 (1, 59), 14°52'N, 67°57'W, 64-66 m, R/V Chain, 26 May 1966. BRAZIL: ANSP 154229 (1, 100), 3°00'N, 37°52'W, R/V Laserre, 7 Mar 1963.

Monopenchelys acuta (Parr, 1930) Figure 871 Type I. Keller, 1976: 111, fig. 13. Rabula acuta. Smith, 1979: 21. Misidentification: Not Rabula acuta (Parr). Eldred, 1969a (?Gymnothorax miliar is).

Distinctive Characters. This is the only western Atlantic muraenid leptocephalus in which the dorsal fin begins approximately 20-25 myomeres behind the level of the anus. Pigment is absent. Description. Total myomeres 128-134 (n = 9), preanal myomeres 54-57 (9), predorsal myomeres 78-82 (9), LVBV 60-62 (5). Proportions as

906

Fishes of the Western North Atlantic, Part 9

% of SL: preanal 46-57 (9), predorsal 66-72 (9), HL 6-8 (7), greatest depth 12-17 (8). Body moderate, deepest point behind midlength, anus slightly behind midbody. Dorsal fin begins distinctly behind level of anus, but closer to anus than to tip of tail. Anal fin begins immediately behind anus. Pigmentation. Absent except in eye. Size. The largest specimen examined was 47 mm SL (ISH Anton Dohrn 5746). It was premetamorphic. Identification. The adult of Monopenchelys acuta is unique among western Atlantic morays in having the dorsal fin originate a moderate distance behind the anus. There are 52-56 preanal and 73-76 predorsal vertebrae. The present leptocephalus is also unique in having its dorsal fin begin a moderate distance behind the anus. In eels, the dorsal and anal fins may move forward at metamorphosis, but there is no known case in which they move backward. The leptocephalus of M. acuta therefore must have its dorsaland anal-fin origins at or behind the equivalent myomeres. Aside from Anarchias, Uropterygius, and Channomuraena, all of whose leptocephali are known, the present leptocephalus is the only one that satisfies these conditions. Its total myomere count also matches the vertebral count of M. acuta (124-135). The conclusion seems reasonable, therefore, that the present leptocephalus is Monopenchelys acuta. Spawning and Growth. Specimens were collected throughout the year. Although the size increased slightly from summer to spring, the sample is too small to be meaningful. Distribution. Sargasso Sea, Gulf Stream, Bermuda, Bahamas, Yucatan Channel, Straits of Florida, and north of Hispaniola. Study Material 11 specimens, 25-47 mm SL. SARGASSO SEA: ISH Anton Dohrn 5746IK-39 (1,47), 26°12'N, 66°11'W, 85 m, 13 Apr. 1979. GULF STREAM: MCZ 62276 (1, 46), 39°16.7'N, 65°43.9'W, 0-204 m, 28 Sept. 1982. BAHAMAS: ANSP 155577 (1, 37), 22°39.5'N, 75°38.5'W, 0-600 m, 7 Sept. 1980. STRAITS OF FLORIDA: ANSP 156257 (1, 37), 26°00'N/ 79°28'W/ 0-50 m, 24 July 1964. YUCATAN CHANNEL: ANSP 155574 (1, 37), 20°36'N, 87°00'W, 35-45 m, 8 Nov. 1975. 155575 (2, 2528), 20°34'N, 87°03'W, 55 m, 1 Aug. 1975. 155576 (1, 33),

21°27.2'N, 86°00'W/ 27-63 m, 8 Nov. 1975.155890 (1, 43), 21°31.5'N, 85°56.7'W, 13 m, 13 Feb. 1977. 157621 (1, 37), 20°43.5'N, 86°52.0'W, 150 mwo, 14 Feb. 1977. HISPANIOLA: ANSP 156258 (1, 45), 20°03.8'N, 64°59.3'W/ 50 m, 3 July 1971.

(?)Gymnothorax miliaris (Kaup, 1856) Figure 872 Leptocephalus fuliginosus Stromman, 1896: 34, pi. 3, figs. 6-7. Bertin, 1936a: 8, fig. 9. Rabula acuta (not of Parr, 1930). Eldred, 1969a. Keller, 1976: 111. Muraena miliaris(l). Smith, 1979: 21, fig. 30. Misidentification: Not Lycodontis ? miliaris (Kaup). Blache, 1971b: 220, fig. 19.

Distinctive Characters. This leptocephalus is distinguished by the stripe of pigment on the head and the lack of intestinal pigment. Description. Total myomeres 120-125 (n = 12), preanal myomeres 69-74 (11), predorsal myomeres 68-73 (9), LVBV 64-69 (5). Proportions as % of SL: preanal 62-68 (9), predorsal 61-65 (6), HL 7-8 (8), greatest depth 12-17 (8). Body moderate, deepest point behind midlength, anus at about two-thirds SL. Dorsal fin begins above anus. Pigmentation. A horizontally elongate group of melanophores behind and before eye, superficial and deep, forming an ill-defined band, more prominent in larger individuals. Minute melanophores on bases of dorsal, anal, and caudal fins, more numerous posteriorly. Internal melanophores below spinal cord. Size. Eldred's (1969a) largest specimen, 79 mm TL, was beginning to metamorphose. Identification. Eldred's (1969a) identification of this leptocephalus as Rabula (= Monopenchelys) acuta is unlikely for several reasons. First, the myomere count (120-125) does not match the vertebral count of M. acuta (124-135). Second, the leptocephalus has fewer predorsal myomeres than M. acuta has predorsal vertebrae. This means that the dorsal fin would have to move backward at metamorphosis, a process unknown in eels. Third, M. acuta is not congeneric with the Indo-

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907

FIGURE 872. Gymnothorax miliaris (B from Smith, 1979: fig. 30): A. ANSP 155914, 52 mm SL. B. Same; head. C. ANSP 155915, 64 mm SL; tail.

Pacific species placed in Rabula, hence Castle's (1965a) tentative identification of larval Rabula from Australasian waters is irrelevant. Finally, another leptocephalus, described above, provides a much better match with M. acuta than the present one. The identification of this leptocephalus with Gymnothorax miliaris is based entirely on the agreement between myomere and vertebral numbers. Gymnothorax miliaris has 117-126 vertebrae and, aside from Uropterygius macularius, is the only western Atlantic moray known whose vertebral count matches the myomere count of the present leptocephalus. It is a common species and its leptocephalus should be present in collections. Nevertheless, the identification must be considered tentative until further confirmation is available. Spawning and Growth. Specimens were collected throughout the year. No seasonal variation in size was apparent. Distribution. Northern Caribbean, Gulf of Mexico, Straits of Florida, Bahamas, Bermuda, Sargasso Sea. Study Material. 25 specimens, 23-72 mm SL. SARGASSO SEA: ISH Anton Dohrn 5527IK-1 (1, 55), 5666IK-19 (1, 72), 5738IK-35 (1, 60). BAHAMAS: ANSP 155061 (1,41). STRAITS OF FLORIDA: ANSP 156233 (1, 39), 156234 (2, 37). GULF OF MEXICO: ANSP 155438 (1, 23), 155914 (1, 52), 156235 (1, 37), 156236 (1, 59). YU-

CATAN CHANNEL: ANSP 155433 (1,32), 155434 (1, 23), 155435 (2, 23-30), 155436 (1, 27), 155437 (1, 23), 155439 (1, 32), 155915 (1, 64), 157622 (1, 48). MBI 483-487 (1). HISPANIOLA: ANSP 156231 (1, 49), 156232 (1, 51). PUERTO RICO DEEP: ANSP 156237 (1, 72). VIRGIN ISLANDS: ANSP 156230 (1, 64).

Gymnothorax ocellatus Agassiz, 1828 Gymnothorax nigromarginatus (Girard, 1859) Gymnothorax saxicola Jordan and Davis, 1891 Figure 873 Leptocephalus latus Eigenmann and Kennedy, 1902: 87, fig. 6. Leptocephalus gilli Eigenmann and Kennedy, 1902: 88, fig-7. Gymnothorax nigromarginatus. Eldred, 1969b. Keller, 1976: 110. Smith, 1979: 20, fig. 28.

Distinctive Characters: Intestinal pigment present; dorsal fin begins far before anus, at myomere 22-32. Pigment on top and bottom of intestine. Myomeres 136-150. Description. Total myomeres 136-150 (n = 135), preanal myomeres 85-101 (124), predorsal myomeres 22-32 (110), LVBV 77-87 (84). Proportions as % of SL: preanal 69-86 (53), predorsal 20-32 (32), HL 5-10 (37), greatest depth 10-16 (30). Body moderate; gut relatively long, anus at about three-quarters SL. Dorsal fin long, begins near anterior one-fifth to one-third of SL.

Fishes of the Western North Atlantic, Part 9

FIGURE 873. Gymnothorax ocellatus: ANSP 155919, 52 mm SL. A. Whole view. B. Head. C. Gastric region showing ventral pigmentation.

Pigmentation. A row of small melanophores on ventral midline from heart to anus, irregularly double or multiserial around liver; a row of small melanophores along top of intestine from liver to anus. Melanophores on bases of dorsal, anal, and caudal fins. A series of melanophores on dorsal midline from about eighth myomere to origin of dorsal fin. Small melanophores scattered superficially on top of head, internally in nasal capsule and base of brain. Melanophores on palate. A few superficial melanophores at posterior end of lower jaw, and a vertical to slightly oblique row of melanophores from immediately before pectoral fin to heart. Internal melanophores below spinal cord. Size. The largest specimen examined here was 83 mm SL (ANSP 154888). Eldred (1969b) described a metamorphic specimen of 62 mm TL, but judging from her illustration (Eldred, 1969b: fig. 6) the specimen had not really begun the process. The maximum size is probably between 80 and 90 mm SL. Variation. Specimens from the Gulf of Mexico have significantly fewer myomeres (136-145, n = 28, x = 142.0) than those from the Caribbean and Bahamas (137-149, 21, 145.2). This corresponds to the difference in vertebral count between G. nigromarginatus (137-147, n = 48, x = 141.5) and G. saxicola (134-147,245,140.2) on the

one hand and Gymnothorax ocellatus on the other (136-151, 165, 144.6). The vertebral counts of G. nigromarginatus and G. saxicola are nearly identical and their leptocephali probably cannot be distinguished. For convenience, the three are treated as a unit here. Identification. Eldred (1969b) identified this leptocephalus from a complete developmental series ranging from eggs to individuals approaching metamorphosis. In addition to the close agreement in myomere and vertebral number, one of the most significant characters is the presence in near-metamorphic specimens of three developing pores in the infraorbital canal along the upper jaw. This is characteristic of the subgenus Neomuraena (G. ocellatus complex plus conspersus and kolpos, see p. 147), whereas other species of Gymnothorax in the area have four such pores. Spawning and Growth. In the northwestern Gulf of Mexico, evidence indicates a spring and summer spawning season. Fifty-nine specimens were collected in April and July-August, none in November and February. Specimens less than 10 mm SL were found in both seasons, but the maximum size increased from 27 mm to 71 mm SL between April and August. The absence of leptocephali in the fall indicates that individuals spawned in July and August complete their development and metamorphose before Novem-

Muraenid Leptocephali ber. The duration of larval life would thus be about 3 months. This is considerably shorter than the 6 to 8 months estimated by Eldred (1969b). In the Caribbean and the southern Gulf of Mexico, seasonal patterns, if any, are obscure. Specimens were collected there in all seasons. Distribution. Widely distributed in the western Atlantic from the Guianas through the Caribbean to the Gulf of Mexico, the Straits of Florida, the Bahamas, the Gulf Stream, and Bermuda. Study Material 865 specimens, 6-83 mm SL. CENTRAL ATLANTIC: ANSP154888 (2,82-83). GULF STREAM: ANSP 154918 (1, 74). BERMUDA-BAHAMAS: ANSP 154859 (6, 48-59). BAHAMAS: ANSP 154865 (1, 40), 154876 (1,54), 154904 (1,32). STRAITS OF FLORIDA: ANSP 154871 (2, 35-42), 154875 (1, 24), 154877 (1, 46), 154878 (1, 47), 154879 (2, 39-50), 154883 (1, 28), 154884 (1, 42), 154885 (1, 65), 154894 (1, 64), 154906 (2, 35-52), 154907 (3, 50-67), 154908 (1, 47), 15^909. (12, 30-52), 154910 (1, 40), 154923 (1, 36), 154924 (1, 34). EASTERN GULF OF MEXICO: ANSP 154887 (1,39). UMML Oregon II 7020 1-15-2 (1, 63), 2-1-2 (1, 18), 2-2-1 (2, 12-16), 2-2-2 (1, 23), 2-4-2 (1, 17), 2-4-3 (1, 14), 2-6-1 (1, 11), 2-7-1 (1, 58), 2-7-2 (1,32), 2-8-1 (1, 25), 2-9-2 (1,14), 2-12-2 (1,35), 2-13-2 (1, 10), 2-16-1 (2, 21-66), 2-19-1 (1, 64), 2-20-2 (1, 28), 2-21-1 (1, 31). WESTERN GULF OF MEXICO: ANSP 154225 (3, 16-61), 154838 (8, 40-66), 154840 (4, 51-60), 154841 (12, 36-69), 154842 (3, 42-66), 154843 (3, 22-70), 154844 (4, 42-58), 154845 (18, 16-52), 154847 (1, 66), 154848 (29,20-54), 154849 (12,41-59), 154851 (4,43-71), 154852 (10, 19-61), 154853 (24, 24-60), 154854 (14, 4462), 154855 (7, 16-64), 154856 (46,17-39), 154857 (4, 3866), 155179 (2,18-23), 155180 (1,15), 155182 (1,15), 155183 (1,25), 155184 (13,18-52), 155186 (1, 27), 155189 (1, 41), 155190 (1,30), 155191 (4,23-36), 155192 (8,21-63), 155193 (10,25-58), 155196 (1, 49), 155197 (1, 53), 155198 (11,2757), 155199 (2,6-18), 155200 (1,58), 155201 (1,43), 155202 (6, 9-24), 155203 (4, 31-66), 155204 (9,15-51), 155205 (1, 54), 155206 (5, 36-67), 155207 (5, 35-59), 155208 (1, 20), 155209 (5, 15-37), 155210 (4, 29-51), 155211 (3, 32-45), 155212 (5, 20-27), 155213 (5, 15-23), 155214 (2, 11-61), 155215 (5, 15-38), 155216 (5, 12-60), 155217 (4, 9-31), 155218 (3, 10-16), 155219 (1, 27), 155220 (2, 35), 155221 (1, 16), 155224 (4, 12-29), 155225 (2, 42-55), 155226 (4, 34-43), 155227 (3, 12-14), 155228 (1, 19), 155233 (1, 25), 155235 (14, 14-53), 155236 (8, 13-20), 155237 (7, 15-48), 155238 (1,33), 155239 (7,27-52), 155240 (3,32-47), 155241 (16, 34-69), 155242 (1, 52), 155243 (1, 22), 155244 (1, 28), 155246 (1,28), 155247 (2,20-26), 155248 (3,7-11), 155249 (1, 22), 155257 (4, 42-59), 155258 (17, 15-57), 155260 (2, 29-48), 155261 (3, 42-50), 155919 (14, 44-57), 156033 (18, 43-67), 156034 (21, 41-78), 156035 (22, 31-67), 156036

909

(162, 40-63). MBI 48 (1, 24), 67 (3, 46-60), 235 (1,27), 333 (1, 65), 777 (3,41-49), 787 (2,21-22), YUCATAN CHANNEL: ANSP 154839 (2, 53-62), 154846 (1, 59), 154850 (1, 56), 155178 (2,25-48), 155181 (1,20), 155185 (1,50), 155187 (1, 50), 155188 (1, 59), 155194 (2, 33-51), 155195 (1, 22), 155222 (1, 39), 155223 (5, 21-31), 155229 (1, 47), 155230 (1, 60), 155231 (1, 48), 155232 (1, 39), 155234 (1, 29), 155245 (1, 32). MBI 180 (1, 32), 484 (1, 39), 483-487 (1). JAMAICA: ANSP 154905 (1, 66). HISPANIOLA: ANSP 154863 (4, 44-62), 154866 (6, 45-57), 154870 (2, 44-51), 154873 (3, 40-51). PUERTO RICO: ANSP 154893 (2, 3639), 154925 (4,25-47). LESSER ANTILLES: ANSP 154861 (2, 62-71), 154867 (3, 37-54), 154889 (1, 43), 154895 (1, 71), 154898 (1, 54), 154900 (1, 61), 154919 (1, 45). UMML Oregon II 7239-13 (1, 33). VENEZUELA: ANSP 154860 (1,64), 154862 (1,61). COLOMBIA: ANSP 154864 (1, 59), 154869 (5, 51-62), 154896 (2, 49-76), 154899 (2, 51-69), 154903 (1, 41). PANAMA: ANSP 154858 (1, 68), 154897 (6, 37-67). NICARAGUA: ANSP 154902 (1, 46). HONDURAS: ANSP 155262 (3, 45-53). GUIANAS: ANSP 154868 (11, 40-61), 154886 (8, 15-57).

Gymnothorax conspersus Poey, 1867 Distinctive Characters. Like Gymnothorax ocellatus but with about 167 myomeres. Description. Total myomeres ca 167 (n = 1), preanal myomeres 109 (1), predorsal myomeres 38 (1), LVBV 96 (1). Proportions as % of SL: preanal 78 (1), predorsal 31 (1), HL 7 (1), greatest depth ca 16 (1). Otherwise identical to Gymnothorax ocellatus except that pigment along bottom of gut extends only from heart to liver. Size. The single specimen is 51 mm SL. Identification. The similarity of this leptocephalus to that of Gymnothorax ocellatus indicates that they are closely related. There are two species in this group whose vertebral counts match the myomere count of the present leptocephalus: Gymnothorax conspersus (163-174 vertebrae) and G. kolpos Bohlke and Bohlke (159-167). The former is distributed widely in the western Atlantic from Brazil to the Straits of Florida, whereas the latter is restricted to the North American continent (Gulf of Mexico, Georgia, North Carolina). As the present leptocephalus was collected in the Virgin Islands, it should represent G. conspersus. Distribution. Virgin Islands.

Fishes of the Western North Atlantic, Part 9

i

1

FIGURE 874. Gymnothorax moringa (B-D from Smith, 1979: fig. 29): A. ANSP 155912, 56 mm SL. B. ANSP 155912, 56 mm SL; head. C. Same; body near gastric region. D. Same; tail.

Study Material One specimen, 51 mm SL. VIRGIN ISLANDS: ANSP 154227,17°56.6'N, 65°06.3'W, ca 0-50 m, Pillsbury 1398, 11-12 July 1971.

Gymnothorax moringa (Cuvier, 1829) Figures 874, 875A Leptocephalus strommani Eigenmann and Kennedy, 1902: 89, fig. 8. Gymnothorax moringa. Eldred, 1970b. Keller, 1976: 109. Smith, 1979: 20, fig. 29.

Distinctive Characters. Fewer than 15 myomeres between origin of dorsal fin and anus; a single, complete series of melanophores on ventral midline of esophagus between heart and liver (Fig. 875A); melanophores before pectoral fin; no melanophores on palate; 137-143 myomeres. Description. Total myomeres 137-143 (n = 143), preanal myomeres 66-74 (145), predorsal myomeres 52-61 (122), LVBV 60-72 (82). Proportions as % of SL: preanal 55-74 (45), predorsal 44-56 (36), HL 5-9 (42), greatest depth 10-16 (40). Body moderate, anus slightly behind midlength. Dorsal fin begins about midbody, slightly before level of anus. Pigmentation. A single row of small melanophores along ventral midline from heart to liver (Fig. 875A); a series of melanophores on top of

intestine from liver to anus. Small melanophores on base of dorsal-, anal-, and caudal-fin rays. A row of melanophores on dorsal midline from about eleventh myomere to origin of dorsal fin. A few small melanophores internally on base of brain. A few small melanophores in front of pectoral fin, sometimes extending ventrally toward esophagus. Melanophores scattered ventrally and laterally on heart. Size. The largest specimen examined here was 72 mm SL (ANSP 154937), premetamorphic. A metamorphosing specimen described by Eldred (1970b: 2) was 74 mm TL. The maximum size thus appears to be 70-80 mm SL. Identification. Along with Gymnothorax ocellatus, this is the most abundant of the Gymnothorat-type leptocephali in the western North Atlantic. Aside from the Gymnothorax ocellatus group, G. moringa is the most common species of Gymnothorax in the western Atlantic. The vertebral count of G. moringa (134-142) matches the myomere count of the present leptocephalus. The other species with similar vertebral counts are much less common, and are unlikely to be represented by such an abundant leptocephalus. For these reasons, the present leptocephalus is identified with some confidence as Gymnothorax mo-

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911

g

B

FIGURE 875. Ventral view of esophagus of three species of muraenid leptocephali showing distribution of pigment. A. Gymnothorax moringa (same pattern also found in Gymnothorax spp. A and B). B. Gymnothorax vicinus (similar pattern also found in Gymnothorax spp. D and E). C Gymnothorax sp. C. pf = position of pectoral fin; g = position of gastric region (i.e., stomach-liver-gall bladder complex).

ringa. Eldred (1970b) reached the same conclusion. Spawning and Growth. In the Caribbean, specimens were collected throughout the year, with no seasonal variation in size. In the western Gulf of Mexico, specimens were collected only in November and February. The 16 November specimens measured 15-35 mm SL, the two February specimens 40-53 mm SL. This suggests a late summer and fall spawning season and a relatively short larval life, but the sample is too small to be reliable. The inability to identify with certainty most of the very young muraenid leptocephali leaves the account of this species incomplete. Many of those specimens are surely Gymnothorax moringa and would add important information on spawning seasons and growth rates. Distribution. Caribbean, Gulf of Mexico, Straits of Florida, Bahamas, Bermuda, and Sargasso Sea. Study Material. 281 specimens, 13-72 mm SL. GULF STREAM: ANSP 154936 (4, 35-55), 154946 (2,

29-35), 154947 (1, 25), 154994 (1, 30). BERMUDA: ANSP 154991 (2,38-53), 155010 (1,41). BERMUDA-BAHAMAS: ANSP 154949 (1, 43), 155000 (1, 64). BAHAMAS: ANSP 154934 (2, 45-63), 154937 (4, 47-72), 154943 (4, 39-55), 154950 (13,44-70), 154951 (1, 60), 154952 (1, 64), 154953 (1, 61), 154954 (1, 66), 154955 (1, 50), 154958 (2, 45-50), 154959 (1, 54), 154966 (1, 40), 154969 (1, 44), 154970 (1, 48), 154971 (2, 41-49), 154974 (1, 53), 154975 (4, 33-42), 154976 (1, 31), 154977 (1, 47), 154984 (1, 35), 154988 (1, 23), 154989 (1, 26), 154992 (1, 51), 154996 (12, 42-56), 154997 (1, 38), 154999 (1, 54), 155001 (5, 13-34), 155003 (1, 26), 155004 (1, 26), 155005 (6, 35-47), 155009 (1, 27), 155070 (1, 45). STRAITS OF FLORIDA: 154960 (1, 36), 154961 (1, 48), 154962 (1, 58), 154963 (1, 46), 154965 (3, 26-47), 154967 (1, 51), 154968 (2, 41-50), 154972 (1, 41), 154973 (1, 41), 154978 (1, 32). UMML Oregon II 7239144 (1, 51). GULF OF MEXICO: ANSP 154983 (2, 30-31), 155303 (12, 15-35), 155310 (1, 27), 155311 (1, 40), 155312 (1, 24), 155313 (1, 25), 155315 (1, 53), 155316 (1, 31). YUCATAN CHANNEL: ANSP 154926 (8,30-61), 154927 (1, 65), 154928 (4, 28-56), 154929 (5, 36-55), 154930 (2, 47-50), 154931 (20, 25-62), 154932 (2, 26-61), 154933 (4, 40-58), 155289 (1, 35), 155290 (2, 32-33), 155291 (1, 30), 155292 (2,43-57), 155293 (1, 41), 155294 (2,20-59), 155295 (1, 36), 155296 (1, 49), 155297 (1, 25), 155298 (10, 29-38), 155299 (1, 35), 155300 (3, 34-39), 155301 (1, 33), 155302

912

Fishes of the Western North Atlantic, Part 9

(18, 23-53), 155304 (1, 32), 155305 (1, 40), 155306 (2, 4748), 155307 (5, 25-64), 155308 (1, 46), 155309 (2, 33-34), 155314 (2, 16-27), 155912 (7, 31-57). MBI 166 (1, 39). JAMAICA: ANSP 154980 (1, 69). HISPANIOLA: ANSP 154935 (9,39-61), 154940 (2,61-64), 154941 (1, 60), 154944 (3, 48-52), 154956 (6, 66-72), 154981 (1, 56), 154985 (1, 52), 154990 (1, 47), 154998 (2, 41-51), 155006 (1, 41). PUERTO RICO DEEP: ANSP 154995 (1, 57), 155007 (1, 60), 155011 (1, 45). LESSER ANTILLES: ANSP 154939 (2, 27-58), 154982 (3, 48-56), 154987 (1, 64), 155008 (2, 58). VENEZUELA: ANSP 154938 (3, 49-70). COLOMBIA: ANSP 154948 (1, 57), 154993 (1,44). HONDURAS: ANSP 155317 (1, 55).

Gymnothorax vicinus (Castelnau, 1855) Figure 875B (?)Leptocephalus forstromi Stromman, 1896: 24, pi. 2, figs. 1-3 (part, two specimens, a and b, with 131-133 myomeres). Bertin, 1936a: 7, fig. 8. Leptocephale 13b. Blache, 1963: 19, pi. 32. Lycodontis mareei (not of Poll, 1953). Blache, 1967d: 1174 (part). Gymnothorax vicinus. Eldred, 1970a: 1, figs. 1-2. Blache, 1977: 42, figs. 12a, 13. Lycodontis vicinus. Blache, 1971b: 222, figs. 20-21.

Distinctive Characters. Row of melanophores below esophagus absent or incomplete (Fig. 875B); melanophores on palate; 131-142 myomeres, 6068 preanal myomeres. Description. Total myomeres 131-142 (n = 46), preanal myomeres 60-68 (45), predorsal myomeres 53-63 (37), LVBV 60-67 (34). Proportions as % of SL: preanal 49-61 (38), predorsal 44-54 (22), HL 5-8 (25), greatest depth 10-15 (25). Body moderate, anus near midlength. Dorsal fin begins slightly before level of anus. Pigmentation. An irregular double row of melanophores beneath heart and a single row beneath liver, but most of esophagus without pigment (Fig. 875B). A series of melanophores along top of intestine from liver to anus. A row of melanophores on dorsal midline from about twelfth myomere to origin of dorsal fin. Minute melanophores on bases of dorsal-, anal-, and caudal-fin rays. A few internal melanophores at base of brain. Melanophores on palate. Internal melanophores below and lateral to spinal cord. Size. Eldred (1970a) described a 72-mm speci-

men that was approaching metamorphosis. Blache (1977: 42) reported specimens as large as 78 mm TL, but none were metamorphosing. The maximum size is probably about 80 mm. Variation. Specimens from the Gulf of Mexico have more myomeres (135-142, n = 11, x = 138.9) than those from the Caribbean, Bahamas, and Straits of Florida (131-139, 19, 134.6). Identification. The evidence supporting this identification is largely circumstantial. First, the myomere count of the leptocephalus matches the vertebral count of G. vicinus (128-140). Second, this is the third most common Gymnothorax-type leptocephalus in the western Atlantic after the G. ocellatus complex and G. moringa, and G. vicinus appears to be the third most common Gymnothorax species. Third, the leptocephalus is found on both sides of the tropical Atlantic, and so is G. vicinus. A further indication may come from an analysis of preanal vertebrae and myomeres. Besides Gymnothorax ocellatus and G. moringa, there are three known species of Gymnothorax in the western Atlantic whose vertebral counts match the myomere count of the present leptocephalus. They are G. funebris (137-142), G. polygonius (135142), and G. vicinus (128-140). Of these, G. funebris has more preanal vertebrae than G. moringa (5761 vs 50-57), G. polygonius has about the same number (51-55), and G. vicinus has fewer (4853). If this character changes proportionately at metamorphosis, then the preanal myomeres of the leptocephali should be related in the same way, that is G. funebris would have more preanal myomeres than G. moringa, G. polygonius would have about the same number, and G. vicinus would have fewer. The present leptocephalus in fact has fewer preanal myomeres than G moringa, and this character also supports its identification as G. vicinus. Gymnothorax funebris can probably be excluded further because its vertebral count matches only the Gulf of Mexico population of the present leptocephalus. The identification could be confirmed by demonstrating that adult G. vicinus show the same variation in vertebral number

Muraenid Leptocephali between the Gulf of Mexico and the Caribbean that the present leptocephali do in myomere number. Spawning and Growth. No seasonal pattern of occurrence is evident in the Caribbean. In the western Gulf of Mexico, most specimens were collected in November and February. Sixteen November specimens measured 16-37 mm SL, six February specimens 26-40 mm SL, and the single April specimen 52 mm SL. No specimens were collected in July-August. This suggests a late summer or fall spawning season in the Gulf and a larval life of perhaps 3-5 months. Distribution. Gulf of Guinea, Brazil, Caribbean, Gulf of Mexico, Straits of Florida, Bahamas, Bermuda, Sargasso Sea. Study Material 88 specimens, 16-62 mm SL. SARGASSO SEA: ISH Anton Dohrn 5560 MT-4 (1,59), 5725IK-33 (1,58). GULF STREAM: ANSP 154472 (1,38), 154475 (1, 40). BERMUDA: ANSP 154474 (1, 52). BERMUDA-BAHAMAS: ANSP 154493 (1, 38). BAHAMAS: ANSP 154480 (1, 37), 154481 (1, 50), 154483 (3, 50-54), 154485 (1, 31), 154486 (1, 46), 154491 (1, 53). STRAITS OF FLORIDA: ANSP 154484 (1, 33). GULF OF MEXICO: ANSP 154487 (1,40), 154488 (1,39), 154494 (1,62), 154495 (1, 52), 155318 (2, 28-30), 155324 (1, 40), 155325 (2, 3031), 155327 (1, 40), 155331 (1, 29), 155332 (1, 26), 155333 (10,16-37), 155335 (1, 33), 155341 (1, 38), 155920 (3, 3962). YUCATAN CHANNEL: ANSP 155319 (4, 19-26), 155320 (2, 23-25), 155321 (1, 38), 155322 (1, 38), 155323 (1, 25), 155326 (1, 31), 155328 (5, 21-44), 155329 (1, 33), 155330 (1, 36), 155334 (1, 30), 155336 (2, 23-25), 155337 (3, 18-28), 155338 (3, 32-47), 155339 (1, 42), 155340 (2, 27-32), 155342 (2, 48-53), 155343 (1, 45), 155344 (3, 2328). HISPANIOLA: ANSP 154468 (3, 44-55), 154469 (2, 42-49), 154470 (1,57), 154471 (1,56), 154477 (1,47), 154482 (1, 41). PUERTO RICO: ANSP 154492 (1, 34). BRAZIL: ANSP 154489 (1, 58).

Gymnothorax species A Figure 875A Distinctive Characters. Pigment present on palate; a single, complete row of melanophores on underside of esophagus (Fig. 875A); melanophores before pectoral fin; total myomeres 142148, preanal myomeres 71-76. Description. Total myomeres 142-148 (n = 5),

913

preanal myomeres 71-76 (5), predorsal myomeres 52-53 (5), LVBV 70-71 (3). Proportions as % of SL: preanal 57-65 (6), predorsal 39-47 (5), HL 5-9 (5), greatest depth 11-13 (5). Body moderate, anus at about two-thirds SL. Dorsal fin begins about 20 myomeres in front of anus. Pigmentation. A single row of melanophores along ventral midline from heart to liver (Fig. 875A). A series of melanophores along top of intestine from liver to anus. Minute melanophores on bases of dorsal-, anal-, and caudal-fin rays. A series of melanophores on dorsal midline from about ninth myomere to origin of dorsal fin. A few melanophores internally at base of brain. Melanophores on palate, immediately below pectoral fin, and on ventral surface of heart. Melanophores internally below spinal cord. Size. The largest specimen examined was 54 mm SL (ANSP 154464). Identification. The myomere count of this leptocephalus overlaps the vertebral count of Gymnothorax funebris (137-142), but the match is not particularly good. The fact that this leptocephalus and Gymnothorax sp. B, described below, are identical except for their myomere counts suggests that they represent two very closely related species. No such species pairs of Gymnothorax adults are known. There are two species of Enchelycore, and the vertebral count of E. nigricans (141-148) agrees well with the myomere count of the present leptocephalus. Arguing against this identification is the relationship between total and preanal vertebrae of the two species. Enchelycore nigricans has more total and preanal vertebrae (141-148 and 58-63, respectively) than does E. carychroa (128-140 and 45-51). Although the Gymnothorax sp. A leptocephalus has more total myomeres than G. sp. B, it has fewer preanal myomeres. This relationship is unlikely to reverse between leptocephalus and adult. The present leptocephalus thus cannot be identified. Distribution. Known from the Bahamas and the Yucatan Channel.

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Fishes of the Western North Atlantic, Part 9

Study Material Five specimens, 34-54 mm SL. BAHAMAS: ANSP 154460 (1, 34), 27°28'N, 78°14'W, 0-16 m, 11 Aug. 1964. 154461 (1, 40), 27°28'N, 79°13'W, 0-31 m, 12 Aug. 1964.154463 (1, 3), 22°38.0'N, 75°18.4'W, 0-2250 m, 23 July 1971. 154464 (1, 54), 25°16.2'N, 77°54.6'W, 60 mwo, 30 Aug. 1969. YUCATAN CHANNEL: ANSP 155069 (1, 41), 20°34'N, 87°03'W, 40-45 m, 1 Aug. 1975.

Gymnothorax species B Figure 875A Distinctive Characters. Pigment present on palate; a single, complete row of melanophores on underside of esophagus (Fig. 875A); melanophores before pectoral fin; total myomeres 139142, preanal myomeres 79-81. Description. Total myomeres 139-142 (n = 6), preanal myomeres 79-81 (6), predorsal myomeres 57-60 (5), LVBV 74-76 (4). Proportions as % of SL: preanal 62-72 (6), predorsal 45-50 (3), HL 5-8 (5), greatest depth 12-14 (4). Otherwise identical to Gymnothorax sp. A. Size. The largest specimen examined was 66 mm SL (ANSP 154279). Identification. This leptocephalus cannot be identified with a known adult. Distribution. Known from the Bahamas, the Yucatan Channel, and off the coast of Colombia. Study Material. Six specimens, 31-66 mm SL. BAHAMAS: ANSP 154276 (1, 45), 26°41'N, 79°05'W, 0-10 m, 12 Aug. 1964.154277 (1,57), 22°01.2'N, 73°39.0'W, 0-755 m, 23 July 1971. 154278 (1, 42), 26°34'N, 79°02'W, 0-29 m, 13 Aug. 1964. STRAITS OF FLORIDA: ANSP 154280 (1, 32), 26°00'N, 79°28'W, 0-50 m, 24 July 1964. YUCATAN CHANNEL: ANSP 155063 (1, 31), 20°36'N, 87°00'W, 35-45 m, 8 Nov. 1975. COLOMBIA: ANSP 154279 (1, 66), 10°19.4'N, 75°59.2'W, 0-70 m, 15 July 1966.

Gymnothorax species C Figure 875C Distinctive Characters. A double row of melanophores on underside of esophagus (Fig. 875C); melanophores on palate but not adjacent to pectoral fin; mid-dorsal pigment begins over first myomere. Description. Total myomeres 133-136 (n = 11), preanal myomeres 61-65 (13), predorsal myo-

meres 57-61 (11), LVBV 60-63 (5). Proportions as % of SL: preanal 52-59 (9), predorsal 49-55 (7), HL 6-9 (8), greatest depth 8-14 (9). Body moderate, anus slightly behind midlength. Dorsal fin begins slightly in front of level of anus. Pigmentation. A double row of melanophores on ventral midline from heart to liver (Fig. 875C). A series of melanophores along top of intestine from liver to anus. A series of melanophores on dorsal midline from first myomere to origin of dorsal fin. Minute melanophores on bases of dorsal-, anal-, and caudal-fin rays. A few melanophores internally at base of brain. Melanophores on palate. An irregular double series of melanophores below heart. Melanophores internally below spinal cord. Size. The largest specimen examined was 67 mm SL (UMML Oregon 7239-20). Identification. The myomere count of this leptocephalus is within the range of the vertebral counts of Gymnothorax hubbsi (133-137), Enchelycore carychroa (128-140), and Muraena retifera (128-135), but no direct evidence links it with them. It remains unidentified. Distribution. Known from off Hispaniola and Colombia in the Caribbean, the Yucatan Channel, the Gulf of Mexico, the Straits of Florida, the Bahamas, and the Gulf Stream. Study Material. 18 specimens, 27-67 mm SL. GULF STREAM: ANSP 154451 (1,38), 30°06'N, 78°42'W, 0-20 m, 26 July 1964. BAHAMAS: ANSP 154452 (1, 51), 26°41'N, 79°05'W, 0-10 m, 12 Aug. 1964. 154453 (1, 50), 26°06'N, 79°10'W, 100 mwo, 31 Aug. 1969. 154456 (2,4655), 25°21'N, 77°59.5'W, 11 July 1969.154459 (1,53), Grand Bahama, ca 16 km WSW of Settlement Point, 6 m depth, 12 June 1964. STRAITS OF FLORIDA: ANSP 154457 (1, 27), 25°45'N, 79°52'W, 0-137 m, 9 Sept. 1963. GULF OF MEXICO: ANSP 155174 (1, 62), NE of Veracruz, Mexico, depth 25 m, 7-8 Aug. 1976. 155175 (1, 35), 20°52.9'N, 93°10.2'W, 40 m, 11 Nov. 1975. YUCATAN CHANNEL: ANSP 154458 (1, 52), 21°29.4'N, 85°55.3'W, 30-55 m, 8 Nov. 1975. 155173 (1, 52), 20°36'N, 87°00'W, 35-45 m, 8 Nov. 1975. 155176 (1,55), 20°31'N, 87°04'W, 45 m, 20 July 1977. 155177 (1, 41), 21°35'N, 85°57'W, 57-60 m, 24 July 1977. HISPANIOLA: ANSP 154454 (2, 55-58), 17°53.5'N, 71°52.4'W, 0-1200 m, 17 July 1970. VIRGIN ISLANDS: UMML Oregon II 7239-24 (1, 30), 18°00'N, 65°00'W, 0167 m, 17 July 1972. COLOMBIA: ANSP 154455 (1, 46),

Muraenid Leptocephali

915

FIGURE 876. Gymnothorax sp. E: MCZ 64501, 48 mm SL. 9°53'N, 76°20.2'W, 0-200 m, 14 July 1966. NORTHEASTERN CARIBBEAN: UMML Oregon II 7239-20 (1, 67), 15°56'N, 64°46'W, 0-223 m, 17 July 1972.

Gymnothorax species D Figure 875B Gymnothorax funebris. Eldred, 1970c.

Distinctive Characters. Row of melanophores below esophagus absent or incomplete (Fig. 875B); melanophores on palate and adjacent to pectoral fin; total myomeres 131-136, preanal myomeres 75-78. Description (including data from Eldred, 1970c). Total myomeres 131-136 (n = 5), preanal myomeres 75-78 (5), predorsal myomeres 54-57 (3), LVBV 69-73 (5). Proportions as % of SL: preanal 67-79 (5), HL 6-12 (4), greatest depth 13-15 (4). Pigmentation. A row of melanophores on ventral midline below liver but not on esophagus (Fig. 875C). A series of melanophores along top of intestine from liver to anus. A series of melanophores on dorsal midline from about tenth myomere to origin of dorsal fin. Minute melanophores on bases of dorsal-, anal-, and caudalfin rays. A few melanophores internally at base of brain. Melanophores on palate and below pectoral fin. Melanophores internally below spinal cord. Size. The largest specimen known is 43 mm SL (ANSP 154223). Identification. Eldred's identification of this leptocephalus as Gymnothorax funebris is clearly in error; the vertebral count of G. funebris (137-142)

is much too high. In pigmentation, the leptocephalus resembles that of Gymnothorax vicinus; it differs mainly in having at least one melanophore below the pectoral fin. Although the total myomere count is also similar to that of G. vicinus, the preanal and LVBV counts are significantly higher. Other species with vertebral counts within the range of the myomere count of the present leptocephalus are Enchelycore carychroa (128-140), Gymnothorax hubbsi (133-137), and Muraena retifera (128-135). No direct evidence links it with any of these. Distribution. The specimens were collected in the southern Straits of Florida and the Bahamas. Study Material. One specimen, 43 mm SL. BAHAMAS: ANSP 154223, data not available.

Gymnothorax species E Figure 876 Distinctive Characters. The relative length of the dorsal fin in this species (beginning approximately 35 myomeres before the anus) is midway between that of the Gymnothorax ocellatus group (60 or more) and that of the remaining Gymnothorax-type leptocephali (20 or fewer). Like the ocellatus group it has pigment on top of the head, but unlike them it lacks pigment on the esophagus and lacks melanophores on the dorsal midline before the dorsal fin. The bandlike distribution of pigment on the head before and behind the eye gives a similar impression to that of Gy mnothorax miliarisf but the latter lacks pigment on top of the head.

916

Fishes of the Western North Atlantic, Part 9

Description. Total myomeres ca 136-140 (2), preanal myomeres ca 73-75 (2), predorsal myomeres 40 (2), LVBV ca 72-73 (2). Proportions as % SL: preanal 54-59 (2), predorsal 31-34 (2), HL 6-7 (2), greatest depth 15 (2). Body moderate, anus near midlength, dorsal fin begins some 35 myomeres before anus. Pigmentation. Melanophores on top of head, on palate, and immediately above and around lower part of nasal capsule; melanophores scattered in a broad band behind eye; a few melanophores on bottom of angle of jaw. Melanophores below heart, but no pigment on bottom of esophagus, liver, or intestine; small melanophores on top of gut, beginning some distance behind gastric region. Small melanophores on base of anal-fin rays.

Size. The larger specimen is 48 mm SL and is premetamorphic. Identification. This leptocephalus cannot be identified with a known adult. The head pigment is similar to that of the leptocephali assigned by Blache (1977: 31-39) to Muraena melanotis, M. robusta, and Gymnothorax maderensis. Those three leptocephali differ in other ways from the present one, and in any case the identifications cannot be accepted uncritically. Distribution. The specimens were collected from the Gulf Stream south of the Grand Banks. Study Material Two specimens, 44-48 mm SL. GULF STREAM: MCZ 64501 (1,48), 41°33'N/ 54°55'W/ 0-35-55 m, 6 Sept. 1964. 78089 (1, 44), 41°23.0'N/ 45°53.3'W/ 600 mwo, 18 Aug. 1984.

Family Derichthyidae: Leptocephali DAVID G. SMITH Characters. Moderate to small leptocephali, maximum size 60-90 mm SL. Body moderate to moderately deep, depth approximately one-fifth to one-sixth SL; tail moderate. Posterior end of body often tends to turn upward just before end of tail. Gut long to moderately long, simple, without swellings or loops. Dorsal fin begins near midlength. Head and snout moderately short to moderately elongate. Pigment sparse. Lateral pigment limited to

small melanophores just below midlateral line on posterior part of body. Sometimes melanophores bordering dorsal margin of eye. No pigment on gut. Composition. The Derichthyidae contains two genera, Derichthys and Nessorhamphus. Their leptocephali are similar in overall form and pigmentation, differing mainly in the degree of elongation of the head and body and the relative length of the gut. Meristic characters also differ.

KEY TO THE DERICHTHYID LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC la. Total myomeres 125-135; preanal myomeres fewer than 100; head and body less elongate Derichthys serpentinus, p. 917 Ib. Total myomeres 135-160; preanal myomeres more than 100; head and body more elongate . . 2 2a. Total myomeres 149-160; North Atlantic Nessorhamphus ingolfianus, p. 919 2b. Total myomeres 135-145; equatorial Atlantic Nessorhamphus danae, p. 920

ment, but the LBVB is much farther forward, at myomere 30-37. Description (from Castle, 1970b: 446; and Keller, 1976: 73). Total myomeres 125-135 (n = 37), preanal myomeres 67-83 (8), predorsal myomeres 45-50 (40), LVBV 59-61 (7), total dorsalfin rays 239-243 (3), dorsal-fin rays before anus 101-122 (4), anal-fin rays 157-166 (3). Body moderately deep, depth about one-fifth SL. Gut moderately long, anus near third quarter of SL. Head and snout relatively short, dorsal profile of head from eye to tip of snout slightly concave. Pigmentation. An irregular series of small melanophores just below midlateral line, confined to posterior part of body, often to postanal region. No other pigment present.

Derichthys serpentinus Gill, 1884 Figure 877 Leptocephalus anguilloides Schmidt, 1916b: 17, figs. 12-14. Derichthys serpentinus. Castle, 1969c: 33; 1970b: 444, fig. 1. Keller, 1976: 73. Smith, 1979: 18, fig. 24.

Distinctive Characters. Leptocephali of Derichthys are deeper-bodied than those of Nessorhamphus and have a shorter head and snout. They also have fewer myomeres than either of the two species of Nessorhamphus. Superficially, the leptocephalus of Derichthys resembles that of Anguilla, but it can quickly be distinguished by the more acute tail, the presence of lateral melanophores, and the greater number of myomeres. Serrivomerid leptocephali also have a simple, unpigmented gut and sparse lateral pig917

Fishes of the Western North Atlantic, Part 9

918

1 mm FIGURE 877. Derichthys serpentinus: ANSP 158292, 42 mm SL, Bahamas (from Smith, 1979: fig. 24). A. Whole view. B. Head. C. Tail.

Size. Maximum size approximately 50-60 mm SL. Variation. There are somewhat fewer preanal myomeres in very small individuals. Seven specimens of 17-43 mm TL had 76-83 preanal myomeres, whereas a specimen of 7 mm had only 67 (Castle, 1970b: 446). There is no evidence of geographic variation. Identification. Castle (1970b) identified the leptocephalus of Derichthys serpentinus from metamorphic specimens. Spawning and Growth. Based on material examined here and on the available literature, spawning in the west-central Atlantic seems to occur in the late winter, spring, and summer. In the Sargasso Sea in March-April, 1979, leptocephali ranged from 11 to 35 mm SL. The leptocephali reported by Keller (1976: 76) from the Bermuda area in September were substantially larger, 34-55 mm SL, including some metamorphic specimens. Castle (1970b: 446) recorded almost the entire range of sizes (7-54 mm TL, including a metamorphic specimen) from one collection made in the Sargasso Sea in June (Dana

855). The absence of specimens smaller than 34 mm in Keller's September sample may or may not mean that spawning has terminated by then; the gear that was used apparently selected against very small specimens (Keller, 1976: 7, 76). All that can be said conclusively, therefore, is that spawning takes place at least from March to June and metamorphosis occurs at least from June to September. Collections from the fall and winter months are needed to delimit the life cycle more precisely. Distribution. Derichthys serpentinus occurs widely through the Atlantic and Indo-West Pacific. In the western North Atlantic it is common in the Sargasso Sea and the Bermuda-Bahamas area, though not as abundant as Nessorhamphus ingolfianus. There are no records from the Caribbean Sea or the Gulf of Mexico. Study Material. 149 specimens: 79 specimens measured, 11-42 mm SL. SARGASSO SEA: UMML Pillsbury 1371 (1). ISH Anton Dohrn 5527IK-1 (1), 5556 MOC 5-6 (1,11), 5603IK-8 (15, 18-30), 5610 IK-9 (2, 18-35), 5623 IK-12 (5, 18-32), 5628 IK-13 (4, 11-29), 5632 IK-14 (2, 18-19), 5638 IK-15

Derichthyid Leptocephali

919

5 mm

B

t mm

FIGURE 878. Nessorhamphus ingolfianus: ANSP 157610, 48 mm SL, Bahamas (from Smith, 1979: fig. 23). A. Whole view. B. Head. C. Tail. (1), 5666 IK-19 (5, 13-26), 5670 IK-20 (1, 22), 5674IK-21 (3, 18-19), 5679 IK-22 (2, 18-20), 5684 IK-23 (5, 17-26), 5689 IK-25 (3, 17-19), 5698 IK-27 (1, 20), 5709 IK-29 (3, 26-32), 5715 IK-30 (1, 24), 5717 IK-31 (4,20-30), 5721IK32 (1, 22), 5725 IK-33 (1, 20), 5731 IK-34 (3, 14-19), 5738 IK-35 (3, 25-38), 5738 IK-37 (1, 12), 5746 IK-39 (1, 25). BERMUDA-BAHAMAS: UMML Pillsbury 1016 (9), 1068 (1), 1071 (1), 1074 (1), 1086 (5), 1089 (2), 1094-1095 (11), 1096 (1). BAHAMAS: ANSP 155253 (6,17-21), 155254 (1, 46), 155255 (3, 24-28), 155256 (1, 11), 157613 (3,16-47), 158292 (1, 42). UMML Gerda 1186 (1). UMML Pillsbury 1102 (1), 1113 (1), 1447 (1). NORTH OF PUERTO RICO: UMML Pillsbury 1375 (3), 1377 (1), 1378 (22), 1379 (3).

Nessorhamphus ingolfianus (Schmidt, 1912) Figure 878 Leptocephalus ingolfianus Schmidt, 1912a: 49, pi. 3, fig. 8. Small larva no. 1, no. 2, no. 3. Lea, 1913: 41, pi. 6, nos. 2-4. Nessorhamphus ingolfianus. Schmidt, 1930: 371, pis. 4-5; 1931a: 487, figs. 3, 5. Beebe, 1935b: 31, figs. 10-11. Keller, 1976: 86. Smith, 1979: 17, fig. 23. Platuronides danae (not of Roule and Bertin, 1924). Beebe and Crane, 1937a: 332, text-fig. 2a-b. Platuronides acutus (not of Parr, 1932). Beebe and Crane, 1937a: 332, text-fig. 9a-d.

Distinctive Characters. The leptocephalus of Nessorhamphus ingolfianus resembles that of Derichthys serpentinus, but the body and snout are

distinctly more elongate. It also has many more myomeres. Serrivomerid leptocephali are also similar, but the LVBV is much farther forward, at myomere 30-37, than it is in either of the derichthyid genera. Nessorhamphus ingolfianus has more myomeres than N. danae (149-160 vs 135145). Description (including data from Schmidt, 1930: 373; Beebe, 1935b: 32; and Keller, 1976: 86). Total myomeres 149-160 (n = 399), preanal myomeres 117-121 (4), predorsal myomeres 62 (1), LVBV 77 (1). Proportions as % of SL: preanal 88-95 (7), predorsal 39-54 (3), head 9-15 (6), greatest depth 13-21 (6). Body moderately elongate, depth about onesixth SL, deepest point behind midlength, tail moderately acute. Gut long, simple, anus near last tenth of SL. Head and snout moderately elongate, dorsal profile of head from eye to tip of snout flat or slightly concave. Pigmentation. A few small melanophores along midlateral line at posterior end of body. A few melanophores bordering dorsal margin of eye. No other pigment. Size. Maximum size 80-90 mm SL. Identification. Schmidt (1930) identified this leptocephalus from metamorphosing specimens.

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Fishes of the Western North Atlantic, Part 9

Spawning and Growth, Like Derichthys serpentinus, Nessorhamphus ingolfianus spawns during the spring and summer, but it does so over a much shorter time span. Keller (1976: 76, 86) reported leptocephali of both species present in the Bermuda area during August and September. Although leptocephali of Derichthys were collected in the Sargasso Sea in March-April, 1979 by the ANTON DOHRN, leptocephali of Nessorhamphus were absent. In the Gulf of Mexico, leptocephali of Nessorhamphus were present in July but not in February, April, or November. Taning (in Schmidt, 1930: 375) stated that in the Sargasso Sea, eggs were especially abundant in May. According to Schmidt (1930: 374), metamorphosis takes place from August to October. This gives a length of larval life of 3 or 4 months. Spawning seems to occur later in the eastern Atlantic. Five specimens were collected between the Canary and Cape Verde islands in November (MCZ 64682, 64683, 64684). Distribution. Nessorhamphus ingolfianus occurs over a broad area of the North Atlantic from the Gulf Stream in the west nearly to the coast of Africa in the east. The southern border of its range coincides with the Antillean Island Arc in the west, while in the east it extends just south of the Cape Verde Islands (Schmidt, 1930: 373). In the north it reaches about 40°N in the Gulf Stream. The species has not been recorded from the Caribbean, but a population exists in the western Gulf of Mexico. Near the equator, it is replaced by Nessorhamphus danae. In the IndoPacific region, N. ingolfianus occurs in the southwestern Pacific from the Marquesas to Australia, centered on the Tropic of Capricorn, and around Madagascar and South Africa. It is absent from the South Atlantic and, apparently, from the North Pacific. Study Material. 75 specimens: 31 specimens measured, 22-83 mm SL.

SARGASSO SEA: UMML Pillsbury 1371 (1). BERMUDA-BAHAMAS: UMML Pillsbury 1016 (7), 1020 (1), 1036 (6), 1049 (3), 1051 (1), 1067 (3), 1068 (1), 1071 (2), 1079 (1), 1085 (1), 1089 (1), 1094-1095 (3). BAHAMAS: ANSP 155067 (1, 48), 157610 (1, 48). UMML Pillsbury 1005 (1), 1120 (1), 1428 (1). GULF OF MEXICO: ANSP 154610 (10, 22-35), 154611 (12, 23-35), 154612 (1, 83), 155902 (7, 23-31). NORTH OF PUERTO RICO: UMML Pillsbury 1378 (2), CENTRAL ATLANTIC: UMML 4027-T1-D (1), 402-7-T3-B (1). UMML Geronimo 2-282 (1). EAST CENTRAL ATLANTIC: MCZ 64682 (1, 63), 64683 (2, 39-60). CANARY ISLANDS: MCZ 64684 (2, 38-55).

Nessorhamphus danae Schmidt, 1931 Nessorhamphus danae Schmidt, 1931a: 487.

Distinctive Characters. Identical to Nessorhamphus ingolfianus but with fewer myomeres (135145 vs 149-160). Description. Total myomeres ca 135-142 (9), preanal myomeres 110-13 (6), predorsal myomeres 46-48 (5), LVBV 73 (1). Proportional measurements as % of SL: preanal 84-93 (7), predorsal 41-43 (2), head 10-13 (5), greatest depth 14-17 (5). Identification. Schmidt (1931a: 487) described Nessorhamphus danae from both leptocephali and adults. Distribution. Nessorhamphus danae occurs along the equator in the Atlantic, Indian, and western Pacific Oceans. Study Material 13 specimens, 26-77 mm SL. EQUATORIAL ATLANTIC: MCZ 73464 (1,30), 8°59'N, 57°34/W, 0-475 m, 27 Sept. 1973. 73465 (1, 63), off Brazil. 73466 (1, 72 metamorphic), off Brazil. 73467 (3, 26-28), 00°53'N, 38°59'W, 120-130 m, 14 Mar 1977. 73468 (1, 26), 00°OrN, 37°40'W, 120-130 m, 15 Mar. 1977. 73469 (1,64), 00°13'N, 35°44'W, 20-25 m, 15 Mar. 1977. 73470 (1, 77 metamorphic), 02°06'N, 33°38'W, 60-70 m, 16 Mar. 1977. 73471 (2, 68 metamorphic), 08°33'N, 44°37'W, 60 m, 23 Mar. 1977. 73472 (1,44), 08°33'N, 44°37'W, 75 m, 23 Mar. 1977. 73473 (1, ca 42), 08°33'N, 44°37'W, 100 m, 24 Mar. 1977.

Family Serrivomeridae: Leptocephali K E N N E T H A. TIGHE

Lateral pigment consisting of small melanophores on base of caudal fin and a small number of melanophores on lateral caudal surface; a variable series of melanophores along lateral midline present in some species. A variable series of small melanophores present along anal fin fold or on the base of anal- and dorsal-fin rays present in larger specimens. A series of small melanophores on dorsal surface of the eye. Composition. The Serrivomeridae is a group of pelagic eels whose leptocephali show little variation in general morphology. Species are characterized mainly by pigmentation and meristics.

Acknowledgments. I thank the following for courtesies extended to me during my visits to their home institutions: M. N. Feinberg (AMNH), K. E. Hartel (MCZ), and C. R. Robins (UMML). Betsy Washington prepared the figures, for which I am very grateful.

Characters. Small to moderate-sized leptocephali, maximum SL generally less than 60 mm prior to metamorphosis. Body moderately deep, depth about one-sixth SL; tail pointed. Gut a simple, narrow tube without loops or thickenings; anus at about three-quarters SL. Origin of dorsal fin at about one-half to three-quarters of SL. Origin of anal fin immediately behind anus. Head and snout pointed; anterior and posterior nostril just in front of eye.

KEY TO THE SERRIVOMERID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC la. Lateral pigment restricted to several small lateral melanophores near tip of tail

Serrivomer beanii, p. 921

Ib. Lateral pigment consisting of a series of lateral melanophores along the myosepta 2a. Total myomeres more than 150, preanal myomeres more than 83

2

Serrivomer lanceolatoides, p. 923

2b. Total myomeres fewer than 150, preanal myomeres fewer than 83

Stemonidium hypomelas, p. 924 redescribed, referred to the Serrivomeridae). Bauchot, 1959: 2 (anatomy, morphology, distribution and identification); 1986: 75 (compiled). Orton, 1964a: 198 (larval nomenclature); 1964b: 438 (larval nomenclature). Mead et al., 1964: 576 (compiled). Castle, 1969c: 25 (index and bibliography). Bauchot and Saldanha, 1973: 229 (checklist). Leptocephalus Species II. Blegvad, 1912: 137 (North Atlantic). Leptocephalus species III. Blegvad, 1912: 138 (North Atlantic). Serrivomer beanii. Bauchot, 1959: 138 (identification with adults).

Serrivomer beanii Gill and Ryder, 1883 Figure 879 Leptocephalus lanceolatus Stromman, 1896:37 (original description, 34°N, 65°™, types ZMUU). Blegvad, 1912: 139 (comparison with Species II and III). Schmidt, 1912a: 48 (North Atlantic); 1912c: 340 (presumed spawning in open ocean); 1916a: 16 (North Atlantic); 1930:374 (comparison with Nessorhamphus). Fish, 1927: 308 (meristics). D'Ancona, 1928a: 107 (meristics, referred to the Congridae); 1928b: 518 (compiled). Bertin, 1935b: 1880 (Oxystomus danae considered metamorphic stage of L lanceolatus); 1936a: 10 (type

921

922

Fishes of the Western North Atlantic, Part 9

FIGURE 879. Serrivomer beannii: MCZ 64807, 32 mm SL. Illustration by B. B. Washington.

Distinctive Characters. Total myomeres more than 150, preanal myomeres more than 83 (premetamorphic specimens only), lateral pigment restricted to several melanophores near the tip of the tail. Description. Total myomeres 153-164 (n = 15), preanal myomeres 84-95 (30), predorsal myomeres 73-89 (20), LVBV 31-39 (33). Proportions as % of SL: preanal distance 78-84 (30), head length 8-13 (30), greatest depth 14-16 (30). Pigmentation. Lateral pigment restricted to approximately six relatively large melanophores on the posterior caudal region. A series of 6 to 12 melanophores on the caudal fin base. An irregular series of small melanophores along the anal fin fold found in larger specimens. A patch of small, round melanophores on the dorsal surface of the eye. Size. Maximum size approximately 60 mm prior to metamorphosis. Identification. Bauchot (1959) identified Leptocephalus lanceolatus as the larvae of S. beanii based on meristic characters. This identification has been confirmed based on metamorphic specimens from the Ocean Acre study (Tighe, 1975). Distribution. These leptocephali are widely distributed throughout the temperate and subtropical North Atlantic. In the Bermuda Ocean Acre Project (Tighe, 1975), leptocephali were found concentrated in the upper 100 m of the water column. Small numbers of leptocephali were taken in discrete depth samples deeper in the water column indicating that a portion of the population may stray into deeper waters. Specimens in the early stages of metamorphosis were also found in the upper water column while late stage rretamorphics (glass eels) were found concentrated at depths of 900-1000 m. Bauchot (1959) reported that leptocephali were found from the

surface to below 400 m with the greatest concentration at 130 m during the day and at 50 m at night. Spawning and Growth. Studies of the life history of Serrivomer beanii off Bermuda (Tighe, 1975) indicate that spawning probably occurs in the late summer or fall. Leptocephali were taken from November through April. The large size range of leptocephali taken in January (Acre 11) indicate that spawning probably occurs over a wide season. Growth occurs over the winter and metamorphosis during the spring. Leptocephali in late stages of metamorphosis as well as glass eels were taken in March and April. Bauchot (1959) felt that the larval period was longer and indicated a span of 12 to 14 months from hatching to metamorphosis. These differences from the Bermuda study may have been due to the greater geographic distribution of samples studied by Bauchot. Study Material A total of 593 specimens, 10-68 mm SL. NORTH ATLANTIC: MCZ 64807 (1, 32), MOClO-20,0 (2, 48-52), MOClO-20,4 (2, 42-50), MOClO-22,3 (7, 2745), MOClO-23,3 (18, 20-47), MOC10-126 (17, 35-58), MOC10-127 (20,23-55), MOC10-128 (36,25-68), MOC10131,3 (2, 46-56), MOClO-137,2 (3, 39-50), RHB 3100 (1, 41). UMML Gerda 263 (2, 38-41), Gerda 496 (2, 26-28), Gerda 497 (1, 30), Gillis Sta. 1B-C (1, 22), Gillis Sta. 2D (12, 10-16), Pillsbury 827 (1, 43), Sands 606-9-T2-D (1, 48). USNM Ocean Acre 2-3N (3,41-45), 2-4N (3,36-48), 2-6N (2, 47-49), 6-5B (1, 54), 8-5N (1, 29), 9-4N (4, 4068), 9-9N (2, 52-62), 9-10N (2, 59-60), 9-12N (17, 43-57), 9-16N (4, 57-60), 9-17N (29, 39-60), 9-22N (16, 39-58), 9-26N (1, 60), 9-31N (2, 61-63), 9-32N (15, 35-57), 11-1M (1, 42), 11-2A (31, 23-51), 11-2B (49, 23-55), 11-2C (90, 27-55), 11-2M (64, 28-55), 11-3A (3, 41-48), 11-3B (16, 26-50), 11-3C (10, 35-53), 11-3M (6,25-43), 11-5A (1,40), 11-7M (2, 51-55), 11-9M (2, 31-47), 11-10M (1, 41), 1111C (3, 46-49), 11-11M (3, 39-53), 13-1A (1,46), 13-1B (6, 34-53), 13-1C (5, 37-56), 13-1M (3, 45-51), 13-2M (1, 50), 13-3M (1, 45), 13-4M (2, 41-45), 13-5M (20, 32-54), 13-

Serrivomerid Leptocephali

923

FIGURE 880. Serrivomer lanceolatoides: MCZ 64806, 35 mm SL. Illustration by B. B. Washington. 6B (4, 45-52), 13-6C (1, 49), 13-7M (5, 34-46), 13-9P (1, 57), 13-15M (1, 36), 13-21M (2, 40-56), 13-22A (1, 57), 1323B (1, 53), 13-27B (2, 42-49), 13-27M (1, 53), 13-28B (1, 48), 13-30A (3, 41-51), 13-30B (1, 50), 13-30C (6, 33-52), 13-31P (11, 30-53).

Serrivomer lanceolatoides (Schmidt, 1916) Figure 880 Leptocephalus lanceolatoides Schmidt, 1916a: 17 (original description, central portion of North Atlantic, types not designated). Fish, 1927: 308 (meristics). D'Ancona, 1928a: 105 (tentatively referred toL humilus). Bauchot, 1959: 2 (anatomy, morphology, distribution and identification). Orton, 1964a: 199 (larval nomenclature); 1964b: 438 (larval nomenclature). Mead et al., 1964: 576 (compiled). Serrivomer br evident atus. Bauchot, 1959:139 (identification with adults).

Distinctive Characters. Total myomeres more than 150, preanal myomeres more than 83 (premetamorphic specimens only), lateral pigment in an irregular series starting at approximately myomere 20 and continuing back to the tail. Description. Total myomeres 156-163 (n = 28), preanal myomeres 89-97 (31), predorsal myomeres 80-88 (20), LVBV 30-36 (46). Proportions as % of SL: preanal 76-88 (20), head 9-13 (20), greatest depth 13-17 (20). Pigmentation. Lateral pigment along the midline consisting of an irregular series of melanophores on the myosepta starting at approximately myomere 20 (14-27 in the material examined); usually one (occasionally two) melanophores per myoseptum, not every myoseptum with a melanophore. A series of 6 to 12 melanophores on the caudal fin base. An irregular series of small melanophores along the anal and dorsal fin bases found in larger specimens. A patch of small, round melanophores on the dorsal surface of the eye.

Size. Maximum size approximately 65 mm prior to metamorphosis. Identification. Bauchot (1959) identified thisleptocephalus based on meristic characters. This identification has been confirmed based on examination of a metamorphic specimen (MCZ 52533). Distribution. Leptocephali of Serrivomer lanceolatoides are widely distributed throughout the temperate and subtropical North Atlantic. Although the adults were found in the Gulf of Mexico, the leptocephali have not been found there. In the Bermuda Ocean Acre Project (Tighe, 1975), small numbers of leptocephali were captured over a wide depth range with no clear depth of abundance. Bauchot (1959) found that leptocephali were found from the surface to below 200 m with the greatest concentration at 70 m during the day and at 100 m during the night. Spawning and Growth. Studies of the life history of Serrivomer lanceolatoides off Bermuda (Tighe, 1975) indicate that spawning probably occurs in the spring or early summer. Leptocephali were taken from June through September. No specimens smaller than 21 mm were collected. This probably indicates that spawning primarily occurs south of the Bermuda area of the Sargasso Sea. Growth occurs over the summer and metamorphosis during the fall although specimens in early stages of metamorphosis were taken as early as July. The single specimen in late metamorphosis (MCZ 52533) was taken in late September. Bauchot (1959) indicated a larval period of at least 10 months for this species. This differs with the results of the Bermuda Ocean Acre Project (Tighe, 1975) and again is probably due to the greater geographic distribution of the samples available to Bauchot (1959).

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Fishes of the Western North Atlantic, Part 9

Discussion. Beebe and Crane (1936) identified leptocephali of Serrivomer lanceolatoides as S. beanii. They based this identification on the assumption that their leptocephali must have belonged to the most common species of serrivomerid eel in their collections, S. beanii. However, since none of the Bermuda Oceanographic Expedition samples were taken during the winter and early spring when larvae of S. beanii are found off Bermuda, this assumption was incorrect. Beebe and Crane (1937a) also had leptocephali which they identified as Platuronides danae and P. acutus. As shown on p. 625, these two species are synonyms of S. lanceolatoides. Examination of the extant material from the Bermuda Oceanographic Expedition at the AMNH has shown that most of the leptocephali identified as Platuronides by Beebe and Crane are in fact Nessorhamphus ingolfianus (AMNH 36197, 36198, 36202, 36208, 36210, 36212, 36213). The remainder of the material was in poor condition and could not be positively identified. However, most of the material could be identified as not belonging in the family Serrivomeridae. Study Material. A total of 154 specimens, 11-71 mm SL. NORTH ATLANTIC: MCZ 52533 (1, 66), 64806 (1, 35), JEC76-3 (13, 15-31), JEC76-4 (5, 21-38), JEC76-10 (1, 31), MOC10-51 (1, 31). UMML Gerda 548 (1, 48), Pillsbury P-100 (3, 11-20), P-166 (1, 19), P-180 (1, 33), P-1016 (4, 14-18), P-1020 (4, 15-38), P-1034 (4, 20-42), P-1036 (1, 30), P-1049 (5,23-38), P-1051 (1,22), P-1052 (1,22), P-1053 (1), P-1055 (4, 18-25), P-1057 (3, 18-51), P-1066 (2, 1827), P-1067 (8, 15-26), P-1068 (5, 20-31), P-1069 (2, 2324), P-1089 (1, 44). USNM Ocean Acre 3-4N (1,65), 4-14P (9,33-54), 4-15P (1,46), 4-19P (1,31), 4-26M (1,27), 4-27M (1, 40), 4-30N (1, 23), 7-7N (1, 49), 7-12N (1, 47), 7-13N (2,21-37), 7-16N (1,45), 7-18N (1,60), 7-19N (1,55), 8-5N (1, 60), 10-15C (1, 57), 10-21N (1, 52), 10-38N (1, 62), 121C (2, 37-47), 12-1M (7, 30-60), 12-2M (1, 43), 12-4A (1, 69), 12-4M (1, 37), 12-5M (2, 32-45), 12-6M (2, 29-53), 12-10C (1, 44), 12-14B (1, 30), 12-16M (1, 29), 12-17B (1, 42), 12-17M (1, 52), 12-18M (1, 38), 12-20B (2,48-50), 1223M (1, 49), 12-24M (1, 46), 12-31B (1, 71), 12-31M (1, 45), 12-32B (2, 33-37), 12-34M (1, 48), 12-35A (1, 60), 1235C (1,39), 12-53N (1,65), 12-77N (1, 53), 14-10M (1, 44), 14-11M (1,52), 14-13M (1,61), 14-25P (12, 25-62), 14-26A (1, 50), 14-27B (1, 47).

Stemonidium hypomelas Gilbert, 1905 Leptocephalus "B." Bauchot, 1959: 96, fig. 80 (morphology and distribution of Pacific larvae). Stemonidium hypomelas. Bauchot, 1959:141 (identification of Pacific larvae). Castle, 1965a: 142 (Pacific leptocephali); 1966b: 59 (Southwest Pacific leptocephali); 1969c: 26 (index and bibliography). Karamovskaya, 1979: 104 (Pacific leptocephalus).

Distinctive Characters. Myomeres fewer than 150, preanal myomeres fewer than 83, lateral pigment in an irregular series starting at approximately myomere 27 and continuing back to the tail. Description (from Bauchot, 1959: 96). Total myomeres 136-143 (n = 30), preanal myomeres 77-82 (30), LVBV 33-36 (30). Proportions as % of SL: preanal 76-83 (30), head 9-14 (30), greatest depth 15-19 (30). Pigmentation (from Bauchot, 1959: 96). Lateral pigment along the midline consisting of an irregular series of melanophores on the myosepta (beginning at myomere 13-46 in material examined by Bauchot); usually one (occasionally two) melanophores per myoseptum, not every myoseptum with a melanophore. A series of 6 to 12 melanophores on the caudal fin base. An irregular series of small melanophores along the anal and dorsal fin bases found in larger specimens. A patch of small, round melanophores on the dorsal surface of the eye. Size. Maximum size approximately 55 mm prior to metamorphosis. Identification. Bauchot (1959) identified the leptocephalus of this species based on specimens from the Pacific. The identification was based on meristic characters as well as the examination of metamorphic specimens. Distribution. The larvae of Stemonidium hypomelas have not yet been reported from the Atlantic Ocean. The absence of this species in collections from the North Atlantic is not surprising due to the small number of specimens of adults taken there. The lack of specimens from the South Atlantic is probably due to the lack of collecting effort in this area with suitable collecting gear. Study Material. None.

Family Nemichthyidae: Leptocephali D A V I D G. SMITH

Characters. Large, slender leptocephali, maximum size 300-400 mm SL. Body elongate, depth about one-tenth to one-twentieth SL; tail moderate to acute. Gut long and simple, without swellings or loops, anus near end of tail. Dorsal fin short, beginning slightly before level of anus. Pectoral fin present. Head with concave dorsal profile and sharp, peg-like snout; nasal capsule small. A series of small melanophores lying along top of dorsal nerve cord from head to tail. Small melanophores on top of intestine, sometimes on bottom of esophagus. Sometimes a few widely spaced melanophores or groups of melanophores on side of body, most conspicuous in young individuals, often lost with growth. Composition. There are two main groups of nemichthyid leptocephali, one representing

Nemichthys and the other representing Labichthys and Avocettina. Leptocephali of Nemichthys are very elongate with an attenuate, filiform tail and extremely numerous myomeres, 300-400 or more. Leptocephali of two of the three recognized species have been identified, N. scolopaceus and N. curvirostris. They are distinguished by pigmentation and meristic characters, especially the preanal myomeres. Leptocephali of Labichthys and Avocettina are only moderately elongate and have a normal caudal structure. The number of myomeres is approximately 170-220. Leptocephali of Avocettina have three pigment spots on the side of the body below the midlateral line, each composed of a group of smaller melanophores. Leptocephali of Labichthys lack these pigment spots.

KEY TO THE NEMICHTHYID LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC la. Body very elongate, tail filiform; LVBV myomeres more than 80 2 Ib. Body moderately elongate; tail not filiform, caudal structure normal; LVBV myomeres fewer than 80 3 2a. Preanal myomeres fewer than 260 in specimens larger than 100 mm SL; three or four lateral melanophores below midlateral line, except in very large individuals Nemichthys scolopaceus, p. 926 2b. Preanal myomeres more than 260 in specimens larger than 100 mm SL; lateral melanophores absent at SL greater than 60 mm, smaller individuals with two lateral melanophores Nemichthys curvirostris, p. 927 3a. Total myomeres ca 190-200; preanal myomeres 170-178 at SL greater than 40 mm; three lateral pigment spots below midlateral line Avocettina infans, p. 929 3b. Total myomeres ca 170-190; preanal myomeres 156-157 at SL greater than 40 mm; lateral pigment absent Labichthys carinatus, p. 931 925

926

Fishes of the Western North Atlantic, Part 9

FIGURE 881. Nemichthys scolopaceus: ANSP 155883, 36 mm SL, Sargasso Sea.

Nemichthys scolopaceus Richardson, 1848 Figure 881 Leptocephalus andreae Schmidt, 1912a: 50, pi. 3, fig. 9. Leptocephalus canaricus Lea, 1913: 40, pi. 6, fig. 1. Nemichthys scolopaceus. Roule and Bertin, 1929: 61, figs. 41, 44-46,48, 54, pis. 2, 6, 7. Beebe and Crane, 1937b: 357, text-fig. 4. Bengtson, 1973. Smith, 1979: 22, fig. 31. Leptocephale A. Roule and Bertin, 1929: 68.

Distinctive Characters. Leptocephali of the two species of Nemichthys in the western North Atlantic can be distinguished by three characters: pigmentation, the number of preanal myomeres, and the maximum size. Except at the very largest sizes, Nemichthys scolopaceus is characterized by three or four melanophores on the side of the body below the midlateral line, near myomeres 18-23,35-44,69-81, and 103-123. These are most conspicuous in young individuals and become progressively smaller with growth. Young leptocephali of Nemichthys curvirostris have two such melanophores, at myomeres 41-47 and 82-90, but these disappear at a SL of about 60 mm. The number of preanal myomeres increases with growth and reaches a maximum of about 260 in N. scolopaceus at about 100 mm SL. In N. curvirostris preanal myomeres continue to increase to a maximum of about 310, at a SL of about 125 mm. At smaller sizes the difference between the two species in this character is progressively less, but overlap probably does not occur at a SL greater than about 60 mm. Nemichthys curvirostris grows considerably larger before metamorphosis than does N. scolopaceus', any unmetamorphosed Nemichthys leptocephalus larger than about 260 mm SL is almost certainly N. curvirostris. Small leptocephali of Avocettina infans have three conspicuous lateral melanophores on the lower body wall and might be confused with leptocephali of Nemichthys scolopaceus of comparable size. In A. infans, however, the mela-

nophores are located at myomeres 26-31, 55-62, and 94-104. In addition, the LVBV myomeres in A. infans are much fewer, 72-77 vs 83-94. Description (including data from Roule and Bertin, 1929: 76,80). Total myomeres at least 380, preanal myomeres 93-257 (n = 112), predorsal myomeres 232-242 (10), LVBV 83-94 (105), posterior end of liver at myomere 42-47 (13), lateral melanophores at myomeres 18-23 (13), 35-44 (105), 69-81 (108), 103-123 (92). Proportions as % of SL: preanal 80-97 (82), greatest depth 4-11 (83). Body greatly elongate, depth about one-tenth SL in smaller specimens, one-twentieth SL in larger specimens. Tail attenuate and filiform. Gut long and simple, anus near end of tail. Dorsal profile of head markedly concave, snout sharp and peg-like. Pigmentation. Four subcutaneous lateral melanophores located below midlateral line, the anteriormost unpaired and closest to notochord, the posterior three paired and somewhat lower; the three posterior melanophores appear first, the anterior one appears somewhat later. A series of small melanophores lying along top of dorsal nerve cord from head to tail; a few larger melanophores at level of notochord. A series of small melanophores along top of gut from about twentieth myomere to anus. Size. Maximum size approximately 260 mm SL. Variation. The distribution and intensity of the lateral melanophores change markedly during growth of the leptocephalus. The posterior three melanophores appear first; the anterior one appears at about 20-30 mm SL. At this stage the melanophores are large and conspicuously expanded; the second and third, particularly, are low on the side of the body, nearly touching the ventral margin. As the leptocephalus grows, the lateral melanophores become progressively smaller and more contracted. They migrate dorsally away from the ventral margin and become

Nemichthyid Leptocephali detached from the body wall. In the most advanced individuals, they often disappear entire-

iy-

Preanal myomeres increase in number as the leptocephalus grows, from fewer than 100 in the smallest individuals to a maximum of about 230260, reached at a SL of slightly more than 100 mm. The number then remains constant until metamorphosis. Identification. Roule and Bertin (1929: 61) identified the leptocephalus of Nemichthys scolopaceus through a complete series of metamorphosing specimens. Spawning and Growth. There is no clear indication of a seasonal spawning pattern. In the Sargasso Sea in March-April, 1979, specimens ranged in size from 11-233 mm SL, indicating a prolonged spawning season there. During the MBI cruises, however, 15 of the 16 specimens collected in the Yucatan Channel were taken in April; they ranged from 60-186 mm SL. None were collected in the summer and fall and only one (73 mm SL, ANSP 154247) in the winter. Remarks. The total number of myomeres is difficult to determine in leptocephali of Nemichthys because of the extremely attenuate tail. There is no evidence that myomeres are added during growth, as some have maintained (Roule and Bertin, 1929: 81). Rather, as the leptocephalus grows, more of the poorly differentiated caudal myomeres become visible. Distribution. Widely distributed on both sides of the North Atlantic, including the Mediterranean and the Caribbean, but apparently absent from the western Gulf of Mexico. Also the South Atlantic and most of the Indian and Pacific Oceans, except the northern and southernmost parts. Study Material 511 specimens, 11-223 mm SL. SARGASSO SEA: ANSP 155883 (2, 35-37). ISH Anton Dohrn 5538 IK-2 (1, 102), 5562 IK-4 (22, 26-118), 5576 IK-5 (29,19-66), 5588 IK-6 (8, 25-90), 5588 MOC 6-0 (1, 30), 5588 MOC 6-7 (5,18-47), 5596 IK-7 (1,56), 5603 IK-8 (17,27-70), 5610 IK-9 (5,11-82), 5615IK-10 (26, 32-156), 5619IK-11 (3,80-233), 5623IK-12 (10,16-163), 5632 Mill (2,107-132), 5638 IK-15 (2,16-30), 5643 IK-16 (13,3689), 5653 IK-17 (34,15-122), 5661 IK-18 (4,17-62), 5666 IK-19 (29-111), 5670IK-20 (3,48-67), 5674IK-21 (12,24-

927

118), 5679 IK-22 (6, 22-49), 5684 IK-23 (7, 53-169), 5688 IK-24 (1, 23), 5689 IK-25 (5, 22-87), 5695 IK-26 (8, 2368), 5703 IK-28 (2, 13-58), 5709 IK-29 (1, 152), 5715 IK30 (1, 55), 5715 MOC 17-7 (1, 27), 5717 IK-31 (16, 27149), 5721IK-32 (1,44), 5725IK-33 (32,16-155), 5731IK34 (3, 19-47), 5738 IK-38 (140, 15-202), 5738 IK-36 (10, 19-55), 5738 IK-37 (3,82-147), 5738 MOC 19 (1,65), 5738 MT-19 (1), 5743 IK-38 (7, 21-52), 5743 MOC 23-3 (1, 95), 5746 IK-39 (5, 32-66), 5750 IK-40 (8, 28-120), 5756 IK-41 (11, 25-188), 5760 MT-21 (2, 97-117), 5761 IK-42 (5, 4567), 5761 MOC 20-0 (1, 49). BAHAMAS: ANSP 154251 (3, 27-91), 154252 (4, 12-101), 155448 (1, 16), 155449 (1, 13). YUCATAN CHANNEL: ANSP 154245 (1,79), 154246 (1, 75), 154247 (1, 73), 154248 (1, 86), 154249 (4, 68-186), 154250 (1, 76), 155447 (2,60-73). MBI 166 (1, 95), 175 (1), 181 (3, 85-171).

Nemichthys curvirostris (Stromman, 1896) Figure 882 Leptocephalus curvirostris Stromman, 1896: 41, pi. 5, figs. 1-2. Bertin, 1936a: 9. Leptocephalus polymerus Lea, 1913: 27, fig. 17, pi. 3, fig. 5. Tilurus curvirostris. Pappenheim, 1914: 188. Leptocephale B. Roule and Bertin, 1929: 81, fig. 46, pi. 3. Beebe and Crane, 1937b: 357. Nemichthys curvirostris. Nielsen and Smith, 1978: 47.

Distinctive Characters. Never more than two lateral melanophores, and these are present only in leptocephali smaller than about 60 mm SL; preanal myomeres more than 260 in specimens larger than 100 mm SL; maximum size at least 360 mm SL. Description (including data from Roule and Bertin, 1929: 82). Preanal myomeres 116-320 (n = 39), predorsal myomeres 294-307 (8), LVBV 85-107 (50). Proportions as % of SL: preanal 8897 (22), predorsal 85-93 (8), greatest depth 3-7 (22). Pigmentation. Small specimens have two large pigment spots on lower body wall at myomeres 41-47 and 82-90; these spots lost at about 60 mm SL. Small internal melanophores along top of dorsal nerve cord from head to tail. Small melanophores on top of gut from about tenth myomere to anus. Size. The largest specimen recorded is 378 mm TL (Pappenheim, 1914). Roule and Bertin (1929: 82) recorded one of 359 mm.

Fishes of the Western North Atlantic, Part 9

FIGURE 882. Nemichthys curvirostris: A. ANSP 155885, 14 mm SL, Gulf of Mexico. B. ANSP 155900, 40 mm SL, Gulf of Mexico. C. ANSP 155923, 285 mm SL, Gulf of Mexico. D. Same; head. E. Same; gastric region.

Variation. As in Nemichthys scolopaceus, the preanal myomeres increase in number with growth. The definitive number of about 310-320 is reached at a SL of approximately 125 mm. The pigment spots are conspicuous in young leptocephali but become smaller with growth; at about 60 mm SL they have disappeared. The number of LVBV myomeres varies somewhat from place to place. Specimens examined

from the western Gulf of Mexico had 92-98 (n = 18), those from the central and eastern South Atlantic 96-107 (n = 8). Roule and Bertin (1929: 82) recorded 85-92 for 22 specimens from the open North Atlantic, although two specimens examined by me from the Sargasso Sea had ca 91 and 94. Identification. The data presented by Roule and Bertin (1929) clearly indicate the presence of two

Nemichthyid Leptocephali species of Nemichthys leptocephali, although the authors did not interpret them that way. Particularly compelling is the graph (Roule and Bertin, 1929:78) showing the divergence in the number of preanal myomeres with growth and the difference in the maximum size. When Nielsen and Smith (1978) showed that adults of two species of Nemichthys are present in the Atlantic, the connection between the adults and leptocephali of both species became clear. The precaudal vertebrae are more numerous in N. curvirostris than in N. scolopaceus, and this is reflected in the more posterior position of the LVBV in the leptocephalus. Also, N. curvirostris metamorphoses at a larger size. Spawning and Growth. In the Gulf of Mexico, the average size increased from winter to spring as follows: February 26-28 mm SL (n = 2, x = 27.0), April 63-98 mm (8, 78.9), July-August 14285 mm (11,157.9). No specimens were collected in the fall. Nemichthys curvirostris thus appears to spawn in the winter, with metamorphosis occurring sometime between the following August and November. A larval life of 8-10 months is thus indicated. Two small specimens of 14 and 54 mm SL (ANSP 155885 and 155440, respectively) were taken in July-August, however, so some spawning must go on outside the peak period. Some caution should be used with these estimates. Full-size leptocephali of this species are so large that they may escape capture by the 2-m net that was used. If this is true, then the length of larval life would be underestimated. Distribution. Across the North Atlantic, including the western Gulf of Mexico but not the Mediterranean. A few leptocephali have been collected in the Caribbean (Roule and Bertin, 1929: 97), but they seem uncommon there and may be waifs; adults of Nemichthys curvirostris are not known from the Caribbean. Also the South Atlantic, Indian and South Pacific Oceans. Study Material. 58 specimens, 14-310 mm SL. SARGASSO SEA: ISH Anton Dohrn 5562 IK-4 (2, 90253), 5588 IK-6 (2, 26-208), 5603 IK-8 (7, 65-129), 5615 IK-11 (1, 51), 5632 IK-14 (2, 175-232), 5632 MT-11 (1, 143), 5653 IK-17 (1, 310), 5666 IK-19 (2, 50-60), 5689 IK-

929

25 (1, 86), 5738 IK-37 (1, 182). MCZ 64505 (5, 19-206), 64512 (1, 152). BAHAMAS: ANSP 155446 (1, 82). GULF OF MEXICO: ANSP 154238 (2, 153-201), 154239 (1, 86), 154240 (1, 79), 154241 (3, 64-94), 154242 (1, 98), 154243 (2, 113-182), 154244 (2, 188-205), 155440 (1, 54), 155441 (1, 28), 155442 (1, 59), 155443 (1, 63), 155444 (1, 26), 155445 (1, 205), 155885 (1,14), 155900 (2, 40-44), 155923 (2, 137-285). SOUTH ATLANTIC MCZ 64513 (2, 186189), 64514 (1, 420 metamorphic), 64515 (4, 160-203), 64516 (1, 181).

Avocettina infans (Giinther, 1878) Figure 883 Borodinula infans?. Karmovskaya, 1975: 97. Avocettina infans. Smith, 1979: 23, fig. 32.

Distinctive Characters. Leptocephali of Avocettina are distinguished from those of Nemichthys by their less elongate body and their normal rather than filiform tail. The leptocephalus of Avocettina infans resembles that of Labichthys carinatus in the form of the body and tail, but it has three lateral pigment spots that L. carinatus lacks. It also has more total myomeres (192-201 vs 179182), preanal myomeres (132-178 vs 130-157), and predorsal myomeres (162-171 vs 153). Description. Total myomeres 192-201 (n = 6), preanal myomeres 132-178 (12), predorsal myomeres 162-171 (2), LVBV 72-77 (10), lateral pigment spots at myomere 26-31 (15), 55-62 (15), 94-104 (14). Proportions as % of SL: preanal 9198 (11), head 3-8 (9), greatest depth 7-13 (9). Body elongate, but not excessively so, depth about one-tenth SL; tail moderately acute. Gut long and simple, anus near end of tail. Dorsal profile of head moderately concave. Pigmentation. Three internal pigment spots on lower half of body wall, each consisting of a cluster of small melanophores. A series of small melanophores on top of dorsal nerve cord from head to tail. A series of small melanophores along bottom of esophagus from heart to near posterior end of liver; a series of small melanophores along top of intestine from gastric region to anus. Size. The largest specimen examined was 150 mm SL (ANSP 154771). Variation. As in the leptocephali of Nemichthys, the number of preanal myomeres increases with

930

Fishes of the Western North Atlantic, Part 9

A

FIGURE 883. Avocettina infans (modified from Smith, 1979: fig. 32): A. ANSP 155267, 20 mm SL, Gulf of Mexico. B. ANSP 154769 or 154770, 45_mm SL, Gulf of Mexico. C. ANSP 157608,113 mm SL, Gulf of Mexico. D. Same; head. E. Same; gastric region. F. Same; tail.

growth. The definitive number of approximately 170-180 is reached at about 40 mm SL. The lateral pigment spots are most conspicuous in small specimens. With growth, these melanophores become smaller and may disappear before metamorphosis; they were not visible in the 150-mm specimen. Identification. Orton (1964a) and Castle (1965a: 136) identified leptocephali of Avocettina from the eastern Pacific and the southwestern Pacific, respectively. The present leptocephali are nearly identical except for minor differences in pigmentation and in some meristic characters. One species of Avocettina is recognized in the western North Atlantic, A. infans. Its vertebral count (187-

202) matches the myomere count of the present leptocephali. Spawning and Growth. All but five of the specimens examined here were collected in April, and this makes it difficult to estimate the spawning season and growth rate. In the Gulf of Mexico, two size groups were apparent in April: 15 specimens of 11-46 mm SL and three specimens of 113-146 m SL. The latter group must have been spawned considerably earlier, but there was no trace of it in the fall or winter collection. The four summer specimens were 31,93,109, and 150 mm SL. Spawning probably takes place over much of the year. Distribution. Eastern and western North Atlan-

Nemichthyid Leptocephali

931

10

FIGURE 884. Labichthys carinatus: A. ANSP 154234, 118 mm SL, Yucatan Channel. B. Same; gastric region. C. ANSP 155888, 20 mm SL, Yucatan Channel.

tic, including the Gulf of Mexico but not the Mediterranean. Also the Indian and North Pacific Oceans. Not as common as leptocephali of Nemichthys. Study Material. 24 specimens, 11-150 mm SL. YUCATAN CHANNEL: ANSP 155269 (1, 14), 155270 (1, 13). GULF OF MEXICO: ANSP 154769 (2, 45-129), 154770(2,46-146), 154771 (1, 150), 154772(1,93), 155018 (1,109), 155019 (1, 31), 155263 (1, 27), 155264 (4, 22-34), 155265 (2, 11-23), 155266 (1, 25), 155267 (1, 20), 155268 (2,11-15), 155271 (2, 24-28), 157608 (1, 113).

Labichthys carinatus Gill and Ryder, 1883 Figure 884 Leptocephalus hjortiBlegvaid, 1913: 136, figs. 1-3 (original description, 21°34'N, 29°50'W, holotype unknown).

Distinctive Characters. The leptocephalus of Labichthys carinatus closely resembles that of Avocettina infans, but it lacks the lateral pigment spots. It also has fewer total myomeres (179-182 vs 192201), preanal myomeres (130-157 vs 132-178), and predorsal myomeres (153 vs 162-171). Description. Total myomeres 179-182 (n = 3), preanal myomeres 130-157 (5), predorsal myomeres 153 (1), LVBV 73-74 (3). Proportions as % of SL: preanal 92-94 (2), head 4(1), greatest depth 8(2). Form of head and body as in Avocettina infans. Pigmentation. Small internal melanophores

along top of dorsal nerve cord from head to tail. Small melanophores along bottom of esophagus from heart to liver; small melanophores internally along top of intestine from gastric region to anus. Young specimens have two large melanophores (or clusters of two or three melanophores) on bottom of gut, one below gastric region and the other farther back near myomere 68. Size. The largest specimen examined was 118 mm SL (ANSP 154234). Variation. Preanal myomeres increase in number with growth. The size at which the definitive number is reached is uncertain because of the small sample. Two specimens of 20 and 24 mm SL (ANSP 155881 and 155888) had 133 and 130 preanal myomeres respectively. Two specimens of 81 and 118 mm (ANSP 154234 and 154363) had 156 and 157. The enlarged ventral melanophores were present only in the two small specimens. Identification. The similarity of the adults of Avocettina and Labichthys indicates that their leptocephali should be similar as well. The present leptocephalus closely resembles that of Avocettina infans, but has fewer myomeres. In this it fits Labichthys carinatus> which resembles Avocettina infans but has fewer vertebrae. Spawning and Growth. The sample is too small to draw firm conclusions, but a prolonged

932

Fishes of the Western North Atlantic, Part 9

spawning season is indicated. In April alone, specimens ranged from 20-118 mm SL. Distribution. The specimens described here came from the Yucatan Channel, the Bahamas, and the Gulf Stream off North Carolina. Adults are widely if spottily distributed in the Atlantic, Indian, and North Pacific Oceans, and their leptocephali should be widespread, too. Study material 13 specimens, 20-118 mm SL. GULF STREAM: MCZ 62282 (1, 70), 36°02.2'N/

71°23.5'W, 0-250 m, 19 Aug. 1982. BAHAMAS: ANSP 154361 (5, 16-82), 23°46.1'N/ 73°14.6'W, 150 m wire out (mwo), 6 Sept. 1980. 154362 (2, 54-58), 24°47.1'N/ 75°26.7'W/ 150 mwo, 31 Aug. 1980. 155065 (1, 43), 26°10.7'N/ 75°44.9'W, 150 mwo, 12 Sept 1980. YUCATAN CHANNEL: ANSP 154234 (1, 118), 20°15'N, 87°14'W,150 mwo, 14 Feb. 1977. 154363 (1, 81), 20°41'N/ 86°55'W, 025 m, 13 Feb. 1977. 155881 (1, 24), 20*42'N, 86°55'W/ 025 m, 13 Feb. 1977. 155888 (1, 20), 20«42'N, 86054'WX 04 mx 13-14 Feb. 1977.

Family Chlopsidae: Leptocephali D A V I D G. SMITH Characters. Small to moderate-sized leptocephali, maximum SL less than 100 mm. Body moderately deep, depth usually about a quarter to a third of SL; tail bluntly pointed. Gut simple, relatively short, anus at or slightly before midlength; kidney ends at or just before anus. Dorsal fin long, beginning at approximately anterior fifth of SL. Pectoral fin well developed, disappearing at metamorphosis in some species. Head moderate. Lateral pigment variable, consisting of small or moderately large melanophores, singly or in clusters, on midlateral line or elsewhere on side of body. Ventral pigment variable, often consisting of small melanophores on bottom of esophagus and along top of intestine. Pigment in some form usually present on head, often including a crescentic patch below eye. Composition. Chlopsid leptocephali form a relatively homogeneous group showing little variation in basic structure. Pigmentation and meristic features are about the only taxonomically useful characters. In most eel families pigmentation tends to characterize genera or groups of closely related species, but in the Chlopsidae this does not seem to be true. The leptocephalus of Kaupichthys hyoproroides, for example, resembles that of Catesbya pseudomuraena more than it does

the leptocephalus of Kaupichthys nuchalis. The leptocephalus of Chilorhinus suensonii closely resembles that of Chlopsis bicolor, although adults of the two genera are quite distinct. Leptocephali of Kaupichthys hyoproroides and Catesbya pseudomuraena have small melanophores scattered over the lateral surface of the body, lined up along the myosepta. Leptocephali of Chilorhinus suensonii and Chlopsis bicolor have a series of small melanophores along the midlateral line. In the former, this series usually consists of a single melanophore per myomere, whereas in the latter there are normally two or three melanophores in each myomere. The leptocephalus identified here as Chlopsis dentatus has a series of clusters of small melanophores along the midlateral line and, in at least some individuals, two additional clusters on the lower body wall anteriorly. In Kaupichthys nuchalis the lateral pigment is reduced to a few small melanophores along the midlateral line on the posterior half of the body. Intestinal pigment is reduced as well, consisting of a few inconspicuous melanophores just in front of the anus. Robinsia catherinae is distinguished by having enlarged melanophores, both on the midlateral line and along the intestine.

KEY TO THE CHLOPSID LEPTOCEPHALI OF THE WESTERN NORTH ATLANTIC la. Ib. 2a. 2b. 3a.

Lateral pigment scattered over entire surface of body 2 Lateral pigment largely confined to midline 3 Myomeres 113-120 Kaupichthys hyoproroides, p. 934 Myomeres 136-141 Catesbya pseudomuraena, p. 935 Lateral pigment confined to posterior part of body; ventral pigment confined to posterior end of intestine; kidney ends a short distance before anus Kaupichthys nuchalis, p. 936 933

934

Fishes of the Western North Atlantic, Part 9

3b. Lateral pigment extending most of length of body; ventral pigment extending most of length of gut; kidney ends at anus 4 4a. Lateral melanophores enlarged, expanded Robinsia catherinae, p. 937 5 4b. Lateral melanophores very small 5a. Lateral melanophores in clusters; myomeres 114-119 (?) Chlopsis dentatus, p. 938 5b. Lateral melanophores distributed more or less singly; myomeres 97-104 or 126-135 6 Chilorhinus suensonii, p. 939 6a. Myomeres 97-104 6b. Myomeres 126-136 7 7a. Lateral melanophores in about every myomere; myomeres 126-136 Chlopsis bicolor, p. 940 7b. Lateral melanophores not in every myomere; myomeres 131-135 (?) Chlopsis sp., p. 942 Kaupichthys hyoproroides (Stromman, 1896) Figure 885 Leptocephalus hyoproroides Stromman, 1896: 39, pi. 4, figs. 5-6. Bertin, 1936a: 5, figs. 5-7. Orton, 1964b: 438, figs. 1-3. Castle, 1964b: 36, fig. lld-g. Kaupichthys hyoproroides. Smith, 1969:396, figs. 3-4; 1979: 24, fig. 33. Karmovskaya, 1975: 100. Keller, 1976: 10, 21.

Distinctive Characters. Melanophores scattered over entire lateral surface of body; myomeres 113-120. Description (western Atlantic specimens). Total myomeres 113-120 (n = 19), preanal myomeres 38-44 (41), predorsal myomeres 14-19 (19). Proportions as % of SL: preanal 38-59 (44), HL 9-15 (45), greatest depth 17-36 (45). Pigmentation, Small melanophores scattered over lateral surface of body, generally following myosepta, extending onto clear area between myomeres and dorsal and ventral margins of body; concentration of myomeres somewhat greater near midlateral line. Melanophores ventrally and laterally on esophagus and liver; a row of melanophores along top of intestine and a second, more diffuse series along bottom of intestine. Melanophores on upper and lower jaws between bases of teeth; two oblique rows of melanophores between angle of jaw and gill area; melanophores ventrally on heart. Size. The largest specimen examined was 53 mm SL (ISH Anton Dohrn 5588). A glass eel was 48 mm SL (Smith, 1969: 399). Identification. Orton (1964b) first showed that Leptocephalus hyoproroides was a chlopsid and suggested that it belonged to the genus Kaup-

ichthys. Smith (1969: 396) confirmed that L. hyoproroides was the leptocephalus of the species known as Kaupichthys atlanticus Bohlke in the western Atlantic and K. diodontus Schultz in the Indo-West Pacific. Spawning and Growth. Specimens examined here were collected in every month but September. In July and August alone, SL ranged from 8-51 mm. Like most tropical eels, Kaupichthys hyoproroides probably spawns throughout the year. In the Sargasso Sea in March-April, 1979, no specimen smaller than 38 mm was collected, This probably indicates that the species does not spawn there and that the specimens were carried up from the south on the currents. Distribution. Widely distributed in the western tropical Atlantic from the Caribbean to the Gulf of Mexico, Straits of Florida, Bahamas, Bermuda, the Gulf Stream, and the Sargasso Sea. Also found in the Indo-West Pacific. Study Material 200 specimens, 8-53 mm SL. 48 specimens from Smith (1969: 399) plus 152 additional specimens. SARGASSO SEA: ISH 5527 IK-1 (1, 35), 5588 IK-6 (1, 53),5588MOC 6-7 (1,51), 5596IK-7 (3,38-46), 5603IK-8 (3,49-53), 5615 IK-10 (4, 40-52), 5632 IK-14 (1, 49), 5653 IK-17 (1, 51), 5661 IK-18 (2, 42-52), 5684 IK-23 (4, 4552), 5698 IK-27 (1, 47), 5709 IK-29 (5, 44-52), 5717 IK-31 (1, 45), 5721 IK-32 (1, 51), 5725 IK-33 (1, 49), 5728 IK-35 (3,49-51), 5738 IK-37 (1, 52), 5746 IK-39 (1, 47), 5750 IK40 (1,45). BERMUDA-BAHAMAS: ANSP 154365 (1). BAHAMAS: ANSP155644 (14,31-40), 155645 (1,16), 155646 (1,15), 155647 (1,28), 155648 (1,30), 155649 (1,21). GULF OF MEXICO: ANSP 155620 (1,45), 155624 (1,20), 155629 (2, 31-35), 155632 (1, 23), 155639 (1, 40), 155640 (1, 36). MBI 769 (1, 51). YUCATAN CHANNEL: ANSP 154364 and 155633 (6, 36-44), 155611 (1, 44), 155612 (5, 10-11),

Chlopsid Leptocephali

935

FIGURE 885. Kaupichthys hyoproroides: ANSP 155641, 39 mm SL (modified from Smith, 1979: fig. 33). A. Whole view. B. Head. C. Tail. 155613 (1, 8), 155614 (1, 23), 155615 (1, 40), 155616 (1, 25), 155617 (2, 22-23), 155618 (23, 8-10), 155619 (1, 36), 155621 (3,23-37), 155622 (1, 51), 155623 (4,15-20), 155625 (1, 43), 155626 (2, 39-41), 155627 (2, 38-41), 155628 (1, 30), 155630 (1,36), 155631 (1,47), 155634 (8,12-15), 155635 (4, 18-24), 155636 (3, 25-34), 155637 (1, 35), 155638 (1, 13), 155641 (2, 21-39), 155642 (1, 35), 155643 (4, 22-48), MBI 501 (1, 35), 571 (1, 44). HAWAII: ANSP 156847 (3, 47-60), 156848 (1, 60).

Catesbya pseudomuraena Bohlke and Smith, 1968 Figure 886 Catesbya pseudomuraena. Smith, 1969: 404, fig. 6. Keller, 1976: 12, 40.

Distinctive Characters. In pigmentation, this leptocephalus is almost identical to that of Kaupichthys hyoproroides, but it has more myomeres. It also grows larger and is more elongate. Description. Total myomeres 136-141 (n = 3), preanal myomeres 46-50 (4), predorsal myo-

meres 19-20 (2). Proportions as % of SL: preanal 41-46 (2), HL 8 (2), greatest depth 11-17 (2). Pigmentation. Essentially identical to that of Kaupichthys hyoproroides. Size. Maximum size at least 75 mm SL (ISH Anton Dohrn 5746). None of the specimens examined were metamorphosing, but at least one (UMML Pillsbury 384,70 mm SL) appeared close to it. The snout was elongate, the nostrils were separate, and the anus appeared to have shifted forward slightly (Smith, 1969: fig. 6). Identification. Smith (1969: 404) identified this leptocephalus primarily on the basis of the unusually high myomere/vertebral count. In addition, the larger specimens show the elongate form of the head and body characteristic of adults of Catesbya pseudomuraena. Distribution. Leptocephali are known from the coast of Colombia, the Straits of Florida, Bermuda, and the Sargasso Sea. The only known adult came from the Bahamas.

936

Fishes of the Western North Atlantic, Part 9

FIGURE 886. Catesbya pseudomuraena: ANSP 153501, 62 mm SL. A. Whole view. B. Anal region. Study Material. Five specimens, 48-75 mm SL. SARGASSO SEA: ANSP 153501 (1, 62), 22°22'N, 61°42'W, 0-130 m, 22 Mar. 1979. ISH Anton Dohrn 5725 IK-33 (1, 72), 25°02'N, 67°38'W, 0-85 m, 10 Apr. 1979. 5746 IK-39 (1, 75), 26°12'N, 66°11'W, 0-85 m, 13 Apr. 1979. STRAITS OF FLORIDA: UMML SL 13 C-2 (1, 48), 25°35'N, 79°25'W, 0-47 m, 27 Feb. 1953. COLOMBIA: UMML Pillsbury 384 (1, 70), 10°24'N, 75°58'W, 0-40 m, 15 July 1966.

Kaupichthys nuchalis Bohlke, 1967 Figure 887 Kaupichthys nuchalis. Smith, 1969:400, fig. 5. Keller, 1976: 11, 27.

Distinctive Characters. This leptocephalus is characterized by the sparse pigmentation on the body. The midlateral pigment is confined to the postanal region and the ventral pigment to the posterior end of the intestine. In addition, the kidney ends slightly but distinctly before the anus. Description. Total myomeres 121-125 (n = 12), preanal myomeres 50-54 (10), predorsal myomeres 22-24 (4). Proportions as % of SL: preanal 49-56 (11), HL 8-12 (14), greatest depth 17-34 (14). Pigmentation. Minute melanophores on mid-

lateral line, beginning approximately at level of anus and extending to end of tail, spaced one per two to three myomeres anteriorly, one per myomere posteriorly. A few minute melanophores on top and sides of gut near anus. Scattered melanophores on head, both superficial and deep, most at eye level, both before and behind eye. A crescentic patch of pigment below eye. Size. The largest specimen examined was 43 mm SL (MCZ 65628). Identification. Smith (1969: 400) identified this leptocephalus on the basis of myomere/vertebral number and pigment retention in a juvenile. Spawning and Growth. All but one of the specimens examined were taken between May and October; the other was taken in December. Keller's (1976: 28) specimens were collected in June, September, and October. No seasonal variation in size was evident, however, and the apparent predominance of summer records may be an artifact. Ten of the 13 July specimens were collected in only three tows (UMML Tursiops 152 and 153, and Pillsbury 384), and one of these tows alone (Pillsbury 384) accounted for six. Distribution. Specimens are known from the eastern and western Caribbean, the Straits of Florida, the Bahamas, the Gulf Stream, the Sar-

Chlopsid Leptocephali

937

FIGURE 887. Kaupichthys nuchalis: MCZ 65628, 43 mm SL. A. Whole view. B. Head.

gasso Sea, and Bermuda. Leptocephali were not collected in the Gulf of Mexico, although adults do occur there (Bright and Cashman, 1974: 346). Study Material. 38 specimens, 22-43 mm SL. 14 specimens from Smith (1969: 400) plus 24 additional specimens. SARGASSO SEA: MCZ 65629 (1, 31), 65630 (1, 39), 65635 (1, 37), 65641 (1, 37), 65642 (1,38). GULF STREAM: MCZ 65628 (1, 43), 65632 (1, 30), 65643 (1, 27), 65644 (1, 27), 65645 (1, 31), 65646 (1, 31). NORTH OF HISPANIOLA: MCZ 65636 (1, 30). BAHAMAS: MCZ 65637 (1, 28), 65638 (1, 32), 65639 (1, 24), 65640 (1,32). CENTRAL CARIBBEAN: MCZ 65633 (1, 36). EASTERN CARIBBEAN: MCZ 64888 (1, 40), 65634 (1, 22), 65630 (5, 32-40).

Robinsia catherinae Bohlke and Smith, 1967 Figure 888 Robinsia catherinae. Smith, 1969: 405, fig. 7. Karmovskaya, 1975: 101. Keller, 1976: 12, 38.

Distinctive Characters. This is the only western Atlantic chlopsid leptocephalus with large, expanded melanophores. Description. Total myomeres ca 125-137 (n =

9), preanal myomeres 43-47 (9), predorsal myomeres 17 (2), LVBV 51 (4). Proportions as % of SL: preanal 36-47 (8), HL 8-11 (6), greatest depth 21-30 (6). Pigmentation. A series of moderately large, expanded melanophores on midlateral line, variable in number (3-16 in specimens examined) and often unequal on the two sides. Several enlarged, paired melanophores along intestine. A few small melanophores behind angle of jaw and on heart. Size. The largest specimen examined was 71 mm SL (ISH Anton Dohrn 5615). Identification. Smith (1969: 405) identified this leptocephalus partly from the agreement in myomere and vertebral numbers and partly from pigment retention in a juvenile. Spawning and Growth. Specimens were collected throughout the year, indicating a prolonged spawning season. Distribution. Known from the Lesser Antilles, north of Puerto Rico, the coast of Colombia, the Yucatan Channel, the Gulf of Mexico, the Straits of Florida, Bermuda, and the Sargasso Sea.

938

Fishes of the Western North Atlantic, Part 9

FIGURE 888. Robinsia catherinae: ANSP 155880, 48 mm SL. Study Material. 23 'specimens, 10-71 mm SL. Six specimens from Smith (1969: 404) plus 17 additional specimens. SARGASSO SEA: ISH Anton Dohrn 5615 IK-10 (1, 71), 5638IK-15 (1, 66), 5674IK-21 (1, 60). GULF OF MEXICO: ANSP 155880 (1, 48). YUCATAN CHANNEL: ANSP 155071 (1, 22), 155783 (4,10-26), 155784 (2,10-11), 155785 (1, 26), 155786 (2, 13), 155787 (1, 25), 155788 (1, 39), 155789 (1, 33).

(?)Chlopsis dentatus (Scale, 1917) Figure 889 Leptocephale 7*. Blache, 1963: 13, pi. 17. Chlopsis dentatus. Blache, 1972: 228, figs. 6-7; 1977: 88, figs. 28a, 29. Keller, 1976: 11, 36. Xenocongridae gen. sp. Karmovskaya, 1975: 101, fig. 3.

Distinctive Characters. Midlateral melanophores in discrete clusters; myomeres 114-119. Description (western Atlantic specimens). Total myomeres 114-119 (n = 2), preanal myomeres 38-39 (2), predorsal myomeres 19 (1), LVBV 49 (1). Proportions as % of SL: preanal 42 (2), HL 11-14 (2), greatest depth 24-33 (2). Pigmentation. A series of clusters of small melanophores on midlateral line from shortly behind head nearly to end of tail. Two additional clusters on side of body near ventral margin of myomeres between head and anus. Melanophores below esophagus and liver; clumps of small melanophores along top of intestine. Small melanophores on base of anal fin. An oblique row of melanophores on side of head behind angle of jaw. Melanophores around heart. Size. The largest specimen known is 59 mm

TL, described and illustrated by Blache (1972:228, figs. 6, 7; 1977: 89, fig. 29b-e). It appears to be in the early stages of metamorphosis, and thus is probably close to maximum size. Variation. Specimens from the Gulf of Guinea have slightly more myomeres (118-126) than those from the western Atlantic (Blache, 1972, 1977). In addition, Blache's illustrations do not show the two clusters of melanophores on the lower body wall; Karmovskaya's (1975: fig. 3) illustration of a specimen from the Caribbean does not show this pigment either, however, and it may simply be a matter of individual variation. Identification. Blache (1972: 228) identified this leptocephalus almost entirely by the agreement in the number of myomeres and vertebrae. Aside from Kaupichthys hyoproroides, Chlopsis dentatus is the only chlopsid species known from the Atlantic whose vertebral number falls in this range. Without metamorphic specimens, however, the identification must remain tentative. Spawning and Growth. Specimens were collected in April, July, August, and November. An extended spawning season is indicated. Distribution. Specimens are known from the eastern Caribbean, the Yucatan Channel, the Gulf of Mexico, the Bahamas, Bermuda, and the Sargasso Sea. Also the Gulf of Guinea. Study Material. Five specimens, 19-48 mm SL. SARGASSO SEA: ISH Anton Dohrn 5653IK-17 (1, 48), 18°05'N, 55°30'W, 0-75 m, 2 Apr. 1979. BAHAMAS: ANSP 154224 (1,19), 25°19'N, 77°54'W, 130 mwo, 29 Aug. 1969. 155062 (1, 18), 22°55.4'N, 75°16.7'W, 150 mwo, 7 Sept. 1980. GULF OF MEXICO: ANSP 155891 (1, 38), 23°12'N,

Chlopsid Leptocephali

939

FIGURE 889. Chlopsis dentatus: ANSP 155891, 38 mm SL. 90°57'W, 70-80 m, 11 Nov. 1975. YUCATAN CHANNEL: MBI 713 (1, 47), 18°45'N, 87°30'W, 57 m, 23 July 1977.

Chilorhinus suensonii Liitken, 1852 Figure 890 Leptocephalus feathersi Fowler, 1944: 126, fig. 45. Chilorhinus suensoni. Smith, 1969: 392, fig. 2; 1979: 24, fig. 34. Karmovskaya, 1975: 101, fig. 3. Keller, 1976: 10, 14.

Distinctive Characters. A single series of melanophores along midlateral line; myomeres 97104.

Description. Total myomeres 97-104 (n = 57), preanal myomeres 40-47 (56), predorsal myomeres 20-27 (40). Proportions as % of SL: preanal 44-57 (56), HL 9-13 (57), greatest depth 25-37 (55). Pigmentation. A single series of small melanophores along midlateral line, extending most of length of body; usually one melanophore per myomere, but occasionally more than one. Melanophores below esophagus and liver; a series of melanophores along top of intestine. An oblique row of melanophores behind angle of jaw. A crescentic patch of pigment below eye.

B

FIGURE 890. Chilorhinus suensonii. ANSP 155895, 36 mm SL. A. Whole view. B. Midlateral section showing pigment.

Fishes of the Western North Atlantic, Part 9

940

10 mm

B

1 mm

FIGURE 891. Chlopsis bicolor: MCZ 65627, 36 mm SL. A. Whole view. B. Head.

Size. The largest specimen examined was 56 mm SL (ISH Anton Dohrn 5750). Four metamorphic specimens measured 30-40 mm SL (Smith, 1969: 394). Identification. Smith (1969: 392) identified this leptocephalus on the basis of relative abundance and agreement in myomere/vertebral number. Several metamorphic specimens provided confirmation. Spawning and Growth. Although the smallest specimens were collected in the summer, the pattern is not completely clear. Only four specimens smaller than 20 mm were represented, and they were all collected in July. Of 22 specimens 2030 mm SL, 14 were taken in July-August and eight in November. On the other hand, specimens as large as 49 mm SL were also collected in July. Distribution. Widely distributed in the western Atlantic from the Caribbean to the Gulf of Mexico, Straits of Florida, Bahamas, the Gulf Stream, Bermuda, and the Sargasso Sea.

Study Material. 107 specimens, 9-56 mm SL. 61 specimens from Smith (1969: 394) plus 46 additional specimens. SARGASSO SEA: ISH Anton Dohrn, 5538 IK-2 (2,41), 5615 IK-10 (1, 50), 5666 IK-19 (3, 40-50), 5674 IK-21 (1, 51), 5695 IK-26 (1, 44), 5698 IK-27 (1, 44), 5709 IK-29 (2, 47-50), 5725 IK-33 (3, 38-45), 5738 IK-35 (4, 38-46), 5738 IK-37 (1, 44), 5750 IK-40 (2, 54-56). BAHAMAS: ANSP 154226 (1,31), 155399 (4,9-31), 155400 (2, 31-38), 155401 (3, 14-23), 155402 (1, 15). GULF OF MEXICO: ANSP 155879 (1,49). YUCATAN CHANNEL: ANSP 155394 (1, 20), 155395 (2,14), 155396 (2,22), 155397 (1, 23), 155398 (2, 21-23), 155895 (3, 26-36), MBI 502 (2, 36).

Chlopsis bicolor Rafinesque, 1810 Figures 891, 892A Chlopsis bicolor. Schmidt, 1912b. Grassi, 1913: 130, pi. 7, figs. 31-39, pi. 10, fig. 22, pi. 14, figs. 3-5. D'Ancona, 1931:115, figs. 89-91. Sparta, 1939: 3, figs. 1-10. Smith, 1969: 390, fig. 1. Keller, 1976: 11. Misidentifications: Not Chlopsis bicolor Rafinesque. Castle, 1966a: 31; 1970a: 14. (The large size of these specimens, 55-82 mm TL,

Chlopsid Leptocephali

941

B

' \ \ V - \ \ V V - V

1 FIGURE 892. Midlateral pigment. A. Chlopsis bicolor: MBI 539, 55 mm SL. B. Chlopsis sp.: ANSP 155896, 36 mm SL. indicates that they are probably Chlopsis olokun rather than C. bicolor.)

Distinctive Characters. Leptocephali of Chlopsis bicolor resemble those of Chilorhinus suensonii in pigmentation, but the midlateral pigment usually consists of two melanophores per myomere, resulting in an irregular double row. In addition, the pigment behind the angle of the jaw is sparser than in Chilorhinus suensonii. Chlopsis bicolor also has more myomeres than Chilorhinus suensonii (126-136 vs 97-104). Description (western Atlantic specimens). Total myomeres 126-136 (n = 67, including data from Keller, 1976), preanal myomeres 46-50 (5), predorsal myomeres 20-23 (3). Proportions as % of SL: preanal 41-56 (5), HL 8-11 (5), greatest depth 21-26 (5). Pigmentation. A series of small melanophores along midlateral line, from shortly behind head nearly to tip of tail; except at extreme anterior and posterior end, series consists of two or three melanophores per myomere, the anterior one in each myomere usually below level of posterior one, resulting in an irregular double row (Fig. 892A). Melanophores below esophagus and liver; a series of melanophores along top of intestine. Minute melanophores on posterior end of anal fin, extending onto caudal fin. Two or three melanophores in an oblique row behind angle of jaw. A few melanophores around heart. A crescentic patch of pigment below eye. Size. The largest specimen examined was 55 mm SL (MBI 539). A metamorphic specimen was 44 mm SL (Smith, 1969: 390). Variation. Specimens from the Mediterranean

have slightly more myomeres than those from the western Atlantic. Castle (1966a: 32) reported 131-136 total and 48-53 preanal myomeres in Mediterranean specimens. The eight specimens examined here (Smith, 1969: 390, plus ANSP, MBI, and MCZ specimens) had 127-131 total and 46-50 preanal myomeres. Keller (1976: 13) reported counts as high as 136 from Bermuda, however, so the overlap is considerable. Identification. The leptocephalus of Chlopsis bicolor was identified from the Mediterranean through metamorphic specimens (Schmidt, 1912b). Spawning and Growth. Specimens weje collected throughout the year. Seasonal spawning is not indicated. Distribution. In the western Atlantic, leptocephali are known from the Yucatan Channel, the southern Gulf of Mexico, the Straits of Florida, the Bahamas, Bermuda, and the Sargasso Sea. They seem to be most common in the BermudaSargasso Sea area; Keller (1976: 30) recorded 62 specimens from the Bermuda Ocean Acre, and the 1979 ANTON DOHRN cruise collected nine specimens in the Sargasso Sea. By contrast Smith (1969: 390) recorded only three specimens from the Straits of Florida and Bahamas, and the MBI expeditions took only three from the Gulf of Mexico and Yucatan Channel. Specimens from the Gulf Stream (MCZ) all came from the center of warm-core rings. Leptocephali of this species are common in the Mediterranean. Study Material. 55 specimens, 34-55 mm SL. Three specimens from Smith (1969: 390) plus 52 additional specimens.

942

Fishes of the Western North Atlantic, Part 9

SARGASSO SEA: ISH Anton Dohrn 5527 IK-1 (1, 38), 5556 MOC 5-5 (1, 52), 5588 IK-6 (1, 54), 5643 IK-16 (1, 48), 5653 IK-17 (1, 51), 5684 IK-23 (1, 46) 5695 IK-26 (2, 52), 5709 IK-29 (1, 52). GULF STREAM: MCZ 63292 (27, 25-36), 63293 (1,38), 63294 (1,28), 63295 (2,37-38), 63296 (2,35), 63297 (3,29-37), 63298 (2,26), 63299 (1,29), 65627 (1, 36). GULF OF MEXICO: ANSP 155068 (1, 47). MBI 539 (1, 55). YUCATAN CHANNEL: ANSP 155898 (1,34).

(?)Chlopsis species Figure 892B Distinctive Characters. This leptocephalus resembles that of Chlopsis bicolor, but both the midlateral and intestinal melanophores are more irregularly and widely spaced. The myomere count is also slightly higher. Description. Total myomeres 131-135 (n = 5), preanal myomeres 43-48 (5), predorsal myomeres 17-20 (3), LVBV 49-54 (4). Proportions as % of SL: preanal 40-48 (5), HL 9-11 (5), greatest depth 22-27 (5). Pigmentation. A single irregular row of small melanophores on midlateral line; these melanophores tend to be distributed in groups, often more than one per segment at slightly different levels, separated by several myomeres without pigment (Fig. 892B). Small melanophores on base of anal fin. A few widely scattered melanophores

along top of gut, not evenly spaced. One or two melanophores on heart and on side of head behind angle of jaw. Size. The largest specimen examined was 49 mm SL (ISH Anton Dohrn 5615). There were no metamorphic specimens. Identification. The differences between this leptocephalus and that of Chlopsis bicolor are slight but consistent. Both the lateral and intestinal pigment are more irregular in the former than in the latter. The present leptocephalus also has slightly more myomeres. It is provisionally referred to Chlopsis because of its resemblance to C. bicolor, but the possibility cannot be excluded that it represents a different genus. Distribution. The specimens were collected from the Sargasso Sea, the Yucatan Channel, east of the Bahamas, and north of the Virgin Islands. Study Material. Seven specimens, 24-49 mm SL. SARGASSO SEA: ISH Anton Dohrn 5615IK-10 (1,49), 22°00'N, 58°10'W, 0-90 m, 29 Mar. 1979. EAST OF BAHAMAS: ANSP 156208 (1, 47), 28°27'N, 73°42'W, 200 m wire out, 14 Aug. 1969. YUCATAN CHANNEL: ANSP 155896 (1, 36), 21°33'N, 85°54'W, 13 m, 15 Feb. 1977. 156238 (1, 24), 21°28'N, 86°00'W, 27-63 m, 8 Nov. 1975, 156239 (1, 35), 20°34'N, 87°01'W, 30-40 m, 8 Nov. 1975, MBI 502 (1, 45), 21°34'N, 85°54'W, 13 m, 15 Feb. 1977. NORTH OF VIRGIN ISLANDS: ANSP 156206 (1, 36), 19°50'N, 65°14'W, 0-5150 m, 2-3 Feb. 1969.

Family Heterenchelyidae: Leptocephali DAVID G. SMITH Characters. Moderate-sized leptocephali, maximum TL approximately 90 mm. Body moderate to moderately elongate, tail moderate. Gut simple, relatively long, anus at about four-fifths TL; kidney ends near middle of gut. Dorsal fin begins near midbody. Pectoral fin present. Head and snout short, dorsal profile strongly convex. A series of moderately large melanophores along midlateral line from shortly behind head to end of tail. A series of moderately large somatic melanophores along ventral margin of gut from

throat to anus, sometimes continuing posteriorly to tip of tail Melanophores below heart and on lower jaw. Composition. Blache (1977: 63) described the leptocephali of five species of Heterenchelyidae from the Gulf of Guinea. They are similar in overall appearance, differing mainly in meristic characters. One heterenchelyid species is present in the western North Atlantic, Pythonichthys sanguineus Poey, but its leptocephalus has not been collected.

FIGURE 893. Pythonichthys microphthalmus: MCZ 65626, 39 mm SL. A. Whole view. B. Head.

943

Family Cyematidae: Leptocephali DAVID G. SMITH

nized in the family Cyematidae: Cyema atrum Giinther and Neocyema erythrosoma Castle. Two cyematid leptocephali are also known. One of them has been conclusively identified with Cyema atrum. The other, Leptocephalus holti Schmidt, may be the larva of Neocyema, but this has not been confirmed. The two leptocephali are distinguished by the body depth, pigmentation, and number of myomeres.

Characters. Moderate-sized leptocephali, maximum SL approximately 70 mm. Body moderately deep to very deep, depth one-sixth to onehalf SL, tail moderately acute. Gut moderately long with several prominent loops, preanal length between two-thirds and three-quarters SL. Dorsal fin begins over or somewhat before level of anus. Pectoral fin present. Head and snout long and pointed. Composition. Two species are currently recog-

KEY TO THE CYEMATID LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC 1. Total myomeres 72-79; lateral pigment scattered over surface of body Cyema atrum, p. 944 2, Total myomeres ca 99-112; lateral pigment absent or confined to midline Leptocephalus holti, p. 945 63-73 (48), predorsal 63-74 (38), head 11-20 (49), greatest depth 18-58 (41). Body very deep, about half SL in mid- to fullsize individuals; body deepens abruptly behind head, anterior part of esophagus vertical in larger specimens. Posterior half of gut with four prominent loops or arches. A large, ventral liver lobe anteriorly near level of sixth to ninth myomere. Space between dorsal surface of intestine and ventral margin of myomeres filled with pancreatic tissue from gastric caecum to penultimate intestinal loop. Kidney ends over penultimate loop. Dorsal fin begins above anus. Head and snout long; eye located posteriorly, nearly overhung by anteriormost dorsal myomeres; snout long, triangular in lateral view; nasal capsule small. Pigmentation. Moderate to moderately small melanophores scattered over side of body, more

Cyema atrum Giinther, 1878 Figure 894 Unnamed. Murray and Hjort, 1912a: fig. 79. Leptocephalus Cyematis atri. Lea, 1913: 19, fig. 11, pi. 2, fig. 5. Leptocephalus sp. Roule, 1914b: 9, fig. 5. Leptocephalus sp. F. Roule, 1919: 105, pi. 7, fig. 6-6a. Cyema atrum. Roule and Bertin, 1929:101, figs. 56-57, pi. 9. Bertin, 1937: 4, figs. 1-7. Keller, 1976: 82. Smith, 1979: 12, fig. 15.

Distinctive Characters. With its deep body, long snout, scattered lateral pigment, and looped gut, this is one of the most distinctive and immediately recognized of all leptocephali. It has fewer myomeres than any other known leptocephalus except Megalops, Elops, and Albula. Description (from Bertin, 1937: 8). Total myomeres 72-79 (n = 45), preanal myomeres 37-46 (49), LVBV 36 (1). Proportions as % of TL: preanal 944

Cyematid Leptocephali

945

5 mm FIGURE 894. Cyema atrum: UMML Gilliss 84, 42 mm SL (from Smith, 1979: fig. 15). A. Whole view. B. Head.

numerous in larger specimens, concentrated near midlength. Several melanophores on gut, including one dorsally on each intestinal loop and a few ventrally. A few melanophores on dorsal margin of body. Size. Maximum size approximately 70 mm SL. Variation. The depth of the body increases with growth from about a quarter to a half of the SL. The definitive value is reached at a SL of about 35 mm. Identification. Lea (1913: 19) identified the leptocephalus of Cyema atrum because of its unusually low myomere number. Roule and Bertin (1929: 101) confirmed the identification through metamorphic specimens. Spawning and Growth. Bertin (1937: 27) estimated that the leptocephalus stage of Cyema atrum lasts about 2 years. This was based on the apparent presence of two age groups in SeptemberNovember, one of 10-30 mm TL and one of 4862 mm. Two additional metamorphic specimens supposedly represented the third year class. Bertin's data are suggestive of at least a 1-year cycle, although evidence for the second year is less convincing. Keller (1976: 85), however, recorded from Bermuda specimens of 23 and 49 mm SL in February and 29 and 38 mm in August, values that do not suggest two size classes. Further study

is necessary, but the 2-year figure should be accepted with caution. Distribution. Leptocephali of Cyema atrum are distributed widely over the North Atlantic from the Sargasso Sea to Africa. There are no records from the Caribbean or the Gulf of Mexico or from north of about 45°N. The species also occurs in the South Atlantic and the Indo-Pacific. Study Material. 11 specimens, 13-45 mm SL. CENTRAL ATLANTIC AMAZONIAN: MCZ 60594 (1, 13), 00°56.4'N, 29°37.0'W, 500 m, 18-19 Nov. 1978. 60596 (1, 31), 11°00'N, 41°31'W, 475-0 m, 18 Sept. 1973. 60598 (1, 29), 09°02'N, 43°48'W, 495-0 m, 20 Sept. 1973. 60599 (2, 19-32), 07°43'N, 42°04'W, ca 100 m, 23 Mar. 1977. 60590 (1, 43), 06°44.0'N, 31°43.5'W, 2000 mwo, 22 July 1983. 60593 (1, 35), 10°46.8'N, 49°01.3'W, 2000 mwo, 29 July 1983. CENTRAL NORTH ATLANTIC: MCZ 60595 (1, 17), 26°27'N, 39°38'W, 530-600 m, 2 Dec. 1970. 60597 (1, 39), 34°49'N, 24°32'W, 700-740 m, 8 July 1972. 62273 (1, 45), 42°14.8'N, 42°57.1'W, 1500 mwo, 19 Aug. 1984. LOCATION UNCERTAIN: UMML Gilliss 84 (1,42), data unavailable.

Leptocephalus holti Schmidt, 1909 Figure 895 Leptocephalus holti Schmidt, 1909a: 6, fig. 2, pi. 1, fig. 7 (original description, 48°55'N, 12°03'W, holotype ZMUC). Raju, 1974a: 559. Castle, 1977c: 75. Smith, 1979: 13, fig. 16.

946

Fishes of the Western North Atlantic, Part 9

FIGURE 895. Leptocephalus holti: SIO 70-118, 40 mm TL (from Raju, 1974a: fig. 4B). A. Whole view. B. Head. Unknown Pacific Leptocephalus. Raju, 1974a: 559, fig. 4B.

Distinctive Characters. Leptocephalus holti differs from the leptocephalus of Cyema atrwn as follows: body shallower, lateral pigment absent or confined to midline, and more numerous myomeres (ca 99-112 vs 72-79). Description. Atlantic specimens (including data from Schmidt, 1909a: 6): Total myomeres ca 99112 (n = 3), preanal myomeres ca 56-67 (4), preanal length 70-74% SL (3), depth 15-19% SL (2). Pacific specimen (Raju, 1974a: 559): Total myomeres 102 (1), preanal myomeres 56 (1), predorsal myomeres 38 (1), LVBV 48 (1). Proportions as % TL: preanal length 50 (1), head length 28 (1), greatest depth 31 (1). Body moderately deep, depth about one-sixth to one-third SL; body deepens gradually behind head. Gut with a distinct swelling at gastric region and three loops or arches behind this. A compact liver lobe near 17th myomere, contributing to swelling of gut. Pancreas compact, located just behind liver and gall bladder. Kidney ends just before last intestinal loop. Dorsal fin begins some 20 myomeres before anus. Head and snout long; eye located posteriorly, close to anteriormost myomeres; snout long and pointed; nasal capsule small.

Pigmentation. Several large melanophores sometimes present midlaterally. Moderately large melanophores on gut: one near pectoral fin, one around gastric region, one dorsally on each intestinal loop, and one ventrally between last two loops. Two melanophores on dorsal margin of body, one above anus and one near origin of dorsal fin. A few melanophores on snout; pigment at tip of jaws; pigment spot behind heart. Size. The largest of the known specimens is 40 mm TL (Raju, 1974a: 559). It is not approaching metamorphosis. Variation. The holotype (Schmidt, 1909a: 6, pi. 1, fig. 7) has five conspicuous, expanded melanophores along the midlateral line at myomeres 16, 29, 45, 60, and 72. None of the three specimens examined here show any trace of lateral pigment. The latter are somewhat smaller (1931 mm SL) than the holotype (34.5 mm TL), but not enough that it should make a difference in pigmentation. The holotype has slightly more myomeres (ca 112) than the present specimens (ca 99-108) and was collected much farther to the northeast (south of Ireland) than the latter (Sargasso Sea and eastern equatorial Atlantic). More material is needed to assess the significance of these differences. The specimen described by Raju (1974a: 559, fig. 4B) from the South Pacific is closer to the

Cyematid Leptocephali present specimens in its myomere count (102), but it resembles the holotype in having five conspicuous lateral melanophores. Identification. The similarities of this leptocephalus to that of Cyema atrum indicate that they are both cyematids. The only other eyematid species known is Neocyema erythrosoma, a peculiar neotenous form based on two specimens collected in the South Atlantic (Castle, 1977c). Only one of the specimens was complete, and it had 108 vertebrae. This is within the range of myomere counts of Leptocephalus holti, but by itself the character is not conclusive. Castle (1977c: 75) pointed out that the lateral pigment of larval Cyema atrum is carried through metamorphosis into the juvenile. Although the types of N. erythrosoma are semi-transparent and almost leptocephaloid in form, they show no trace of the distinctive and conspicuous lateral pigment of L. holti This argument is also inconclusive, because the age of the N. erythrosoma specimens is un-

947

known, and the larval pigment may simply have been resorbed In addition, some populations of L holti apparently lack this pigment. Without further evidence, the identity of Leptocephalus holti cannot be determined. Distribution. Leptocephalus holti is known from the northeastern Atlantic, the Sargasso Sea, the equatorial Atlantic, and the South Pacific Etymology. Named for "the eminent naturalist, Mr. E. W. L. Holt of Dublin, to whom we are indebted for so many important investigations in this region of the Atlantic and who, more than any other, has supported me in my investigations on the larvae of the eels" (Schmidt, 1909a: 7). Study Material. Three specimens, 19-31 mm SL. SARGASSO SEA: ANSP 153490, 21°03'N, 57°54'W, 0150 m, Anton Dohrn 5619 IK-11, 30 Mar. 1979. MCZ 64484 (1, 31), 34°27.0'N/ 71°18.5'W/ 0-250 m, 13 Apr. 1977. EASTERN EQUATORIAL ATLANTIC: MCZ 65647 (1, 20), 04°05.2'N, 17°20.8'W, 75 m, 15 Nov. 1978.

Families Saccopharyngidae, Eurypharyngidae, and Monognathidae: Leptocephali D A V I D G. SMITH

Composition. Leptocephali of Saccopharynx and Eurypharynx, the only genera in their respective families, are very similar in overall morphology. Saccopharynx has a slightly longer and less highly arched intestine than Eurypharynx, and it has more myomeres. Leptocephali of the Monognathidae are known only from one or two metamorphic specimens described by Raju (1974a). They differ principally in having several large midlateral melanophores and some extra melanophores along the dorsal and ventral margins. Castle and Raju (1975: 18) described what may be a saccopharyngoid leptocephalus that differs markedly from both Saccopharynx and Eurypharynx. Its identity is unknown.

Characters. Small leptocephali, maximum TL approximately 40-50 mm. Body deep, depth about one-third or more of TL, tail moderately acute to acute; myomeres V-shaped. Gut moderately short, anus at or slightly behind midlength; esophagus long and simple, constituting half or more than half length of gut; intestine short, distinctly thicker than esophagus, irregularly convoluted or arched and sprinkled with small melanophores; kidney ends slightly before anus. Dorsal fin moderately long, predorsal length 15-42% TL. Pectoral fin present, located relatively far behind head and low on side of body, near ventral margin of myomeres 8-9. Head short and deep, suspensorium greatly elongate. No pigment except on intestine.

KEY TO THE SACCOPHARYNGOID LEPTOCEPHALI IN THE WESTERN NORTH ATLANTIC la. Several large, expanded melanophores on midlateral line Monognathus, p. 953 Ib. No lateral pigment 2 2a. Mouth horizontal, suspensorium not greatly elongate; eye closer to tip of snout than to occiput Unidentified saccopharyngoid leptocephalus, p. 951 2b. Mouth oblique, suspensorium greatly elongate; eye closer to occiput than to tip of snout . . . . 3 3a. Total myomeres 170-240 Saccopharynx spp., p. 948 3b. Total myomeres 103-125 Eurypharynx pelecanoides, p. 950 Saccopharynx species Figure 896

pi. 2, fig. 1. Orton, 1963: 7, figs. 1-4. Bohlke, 1966b: 606. Raju, 1974a: 555, fig. 4C. Smith, 1979: 10.

Distinctive Characters. Leptocephali of Saccopharynx have substantially more myomeres than those of Eurypharynx (170-240 vs 103-125). In addition, the intestine of Saccopharynx is longer and less highly arched. Description (from Bertin, 1938: 1; Orton, 1963; and Raju, 1974a: 555). Total myomeres 170-ca 240

Leptocephalus latus Schmidt 1909a: 4, fig. 1, pi. 1, fig. 6 (original description, 48°41'N/ 11°30'W, holotype ZMUC). Preoccupied by Leptocephalus latus Eigenmann and Kennedy, 1902. Leptocephalus latissimus Schmidt, 1912a: 45 (substitute name for Leptocephalus latus Schmidt 1909). Lea, 1913: 46, fig. 36. Bertin, 1934: 40; 1938: 15, figs. 15a, 16-17,

948

Saccopharyngoid Leptocephali

949

FIGURE 896. Saccopharynx species: ZMUC Dana 1142 I, 32 mm SL, eastern North Atlantic (from Bertin, 1938: pi. 2, fig. 1).

(n = 10), preanal myomeres 38-54 (10), prepectoral myomeres 8-9 (7), LVBV 50 (1). Proportions as % of TL: preanal 46-51 (7), predorsal 15-17 (7), head (snout tip to pectoral fin) 12-15 (8), greatest depth 26-43 (8). Body deep, ovoid or lanceolate in shape, deepest at midbody; tail acute. Esophagus about 12.5 times length of intestine; intestine slightly convoluted. Dorsal fin relatively long, begins near anterior sixth of TL. Head short, very deep, suspensorium greatly elongate, gape oblique. Anterior teeth in upper jaw long and slender, directed anteriorly or anteroventrally. Pigmentation. Small melanophores scattered over surface of intestine. No other pigment. Size. The maximum size is somewhat uncertain. The largest specimen recorded in the literature is the type of L. latissimus, 43 mm TL (Schmidt, 1909a: 4). The specimen looks as if it is beginning metamorphosis: the tail appears drawn-out, the intestine is more compact than in other illustrated specimens, and the pectoral fin has "the first indications of interspinous elements" (Schmidt, 1909a: 4). Raju (1974a: 557) described a metamorphic Saccopharynx of 80 mm TL, but it seems to be nearly if not fully transformed. All we can say at the moment is that metamorphosis occurs at a TL of between 40 and 80 mm.

Variation. The finely tapering tail makes it difficult to count the myomeres accurately. Bertin (1938: 26) gave the counts simply as plus or minus 240. Of the seven specimens he studied, including Schmidt's holotype, six came from the eastern North Atlantic and one from the Indian Ocean. Orton (1963: 7) stated that two specimens from the eastern Pacific had ca 195-200 total and 50-54 preanal myomeres. Raju (1974a: 555), however, gave a count of 170 total and 45 preanal myomeres for another eastern Pacific specimen, values significantly different from both Bertin's and Orton's. Assuming that all the preceding counts are accurate, it is obvious that more than one species is involved. Identification. The present leptocephali are identified as Saccopharynx primarily on the basis of their myomere counts. Vertebral counts for adult Saccopharynx range from about 150 to more than 300 (Nielsen and Bertelsen, 1985). Eurypharynx has significantly fewer vertebrae, 103125 (Orton, 1963: 14), and clearly cannot belong to the present leptocephali. Saccopharynx is also much less common than Eurypharynx, and the present leptocephali are much less common than the leptocephali identified as Eurypharynx pelecanoides. It is impossible to determine which of the various species of Saccopharynx the leptocephali represent.

950

Fishes of the Western North Atlantic, Part 9

FIGURE 897. Eurypharynx pelecanoides: ANSP 157626, 11 mm SL, Yucatan Channel.

Distribution. Leptocephali of Saccopharynx are known from the central North Atlantic, the eastern Atlantic off the northwest coast of Africa (Bertin, 1938: fig. 16), the Indian Ocean near the Seychelles (Bertin, 1938: fig. 17), and the eastern Pacific off southern California (Orton, 1963: 7; Raju, 1974a: 555). Study Material Two specimens, 13-24 mm SL. CENTRAL NORTH ATLANTIC: MCZ 62271 (1, 24), 35°05.4'N, 35°45.1'W/ 500 mwo, 26 Aug. 1984. 62272 (1, 13), 34°50.7'N, 36°29.8'W, 400 mwo, 27 Aug. 1984.

Eurypharynx pelecanoides Vaillant, 1882 Figure 897 Gastrostomus bairdi. Murray and Hjort, 1912a: 104, 749, fig. 545 (metamorphic leptocephalus). Leptocephalus Gastrostomi bairdii. Lea, 1913: 43, fig. 35, pi. 6, fig. 5 (same specimen as Murray and Hjort, 1912a). Leptocephalus pseudo-latissimus Bertin, 1936c: 1540 (original description, North Atlantic and Indo- West Pacific, 123 syntypes ZMUC); 1938: 16, figs. 13-14, 15b, 1617, pi. 2, figs. 2-4. Nybelin, 1948: 49. Leptocephalus pseudolatissimus. Tchernavin, 1947a: 301. Orton, 1963: 11. Bohlke, 1966b: 606. Raju, 1974a: 557, fig. 4d. Smith, 1979: 10. Eurypharynx pelecanoides. Smith, 1979: fig. 9.

Distinctive Characters. Leptocephali of Eurypharynx have fewer myomeres than those of Saccopharynx (103-125 vs 170-240). The intestine is shorter relative to the esophagus, thicker, and more highly arched than that of Saccopharynx.

Description (from Bertin, 1938: 16; Orton, 1963; and Raju, 1974a: 557). Total myomeres 103-125 (n = 66), preanal myomeres 34-41 (89), predorsal myomeres 19-24 (7), prepectoral 8-9 (1), LVBV 35 (1). Proportions as % of TL: preanal 55-61 (13), predorsal 34-42 (10), head 15-24 (12), greatest depth 19-42 (14). Body deep, ovoid or lanceolate in shape, deepest at midbody; tail moderately acute. Esophagus about 2.5-5 times length of intestine, intestine slightly convoluted. Dorsal fin moderately long, begins at about two-fifths TL. Head short, very deep, suspensorium greatly elongate, gape oblique. Anterior teeth in upper jaw long and slender, directed anteriorly or anteroventrally. Pigmentation. Small melanophores scattered over surface of intestine. No other pigment. Size. Metamorphic specimens described by Lea (1913:43), Bertin (1938: 17), and Raju (1974a: 558) are 33,35, and 39 mm TL, respectively. The maximum size of leptocephali of Eurypharynx is thus about 35-40 mm TL. Variation. Body depth is relatively constant throughout growth except at the very earliest stages. A 6.8-mm yolk-sac leptocephalus described by Bertin (1938: 16, fig. 13) had a depth of 19% TL; in 12 other specimens of 7.2-35 mm TL the depth was 32-42% TL. Sixty-two specimens described by Bertin (1938: 26) from the North Atlantic had 115-125 myomeres; two specimens from the Indo-West Pacific had 120-121 myomeres. The early metamorphic

Saccopharyngoid Leptocephali specimens from the western Pacific described by Orton (1963) and Raju (1974a: 558) had 103 myomeres. Eurypharynx pelecanoides is presumed to be a single cosmopolitan species, but detailed studies on geographic variation have not been made. Identification. Bertin (1938: 23) assigned all 123 specimens of his Leptocephalus pseudolatissimus to Saccopharynx because their myomere counts (115125) were higher than the highest vertebral count of Eurypharynx known to him at the time (110). He further identified the eastern Atlantic leptocephali with Saccopharynx harrisoni, although he did not know the vertebral count of that species, and the western Atlantic leptocephali with S. johnsoni (= S. ampullaceus), even though that species had significantly more vertebrae (ca 140, after Girard, 1895) than the leptocephali had myomeres. He explained the latter incongruity by observing that eels with a caudal filament add vertebrae during metamorphosis, a process that has often been assumed but never demonstrated. A further incongruity arose from the fact that all the leptocephali represented the rare Saccopharynx. The much more common Eurypharynx was left with no leptocephali at all. We now know that Eurypharynx has 103-125 vertebrae (Orton, 1963: 14), a figure that encompasses the entire range of myomere counts of Bertin's leptocephali. Leptocephalus pseudolatissimus is clearly the larva of Eurypharynx pelecanoides. Spawning and Growth. Bertin (1938:23) claimed to detect two species of Eurypharynx, or at least "two absolutely distinct races," based on the spawning season. In the western Atlantic, leptocephali smaller than 10 mm TL were found in the spring (February-June), whereas in the eastern Atlantic such small leptocephali were collected in the fall (September-October). He further claimed to see three year classes among the western Atlantic leptocephali. The 0 group was spawned in January-February and reached a mean TL of 9 mm in April; by the second April they attained a mean TL of 15 mm (group I); finally, a third year class, group II, had a mean TL in April of 23 mm. This whole scenario seems

951

to be the product of an overactive imagination. Bertin's own data show leptocephali of less than 10 mm present throughout the February-June period. Furthermore, his samples were heavily biased toward the winter-spring season. The Danish vessels spent little time in the area during the rest of the year, and Bertin had no specimens at all that were collected between June and February. It is more likely that Eurypharynx pelecanoides spawns over an extended period and that the leptocephali metamorphose after only a few months. Distribution. Known from the eastern and western North Atlantic, including the Caribbean and the Gulf of Mexico but not the Mediterranean. Also the Indian Ocean and the western and central Pacific. Study Material. 21 specimens, 10-27 mm SL. SARGASSO SEA: ISH Anton Dohrn 5534 MOC 2-4 (1), 5550 MOC 4-6 (1, 24), 5619 IK-11 (1, 25), 5628 IK-13 (1, 16), 5661 IK-18 (1, 27), 5670 IK-20 (2, 19-26), 5679 IK-22 (2,18-20), 5684 MOC 13-6 (1,10), 5688 MOC 14-5 (1,13), 5721 IK-32 (1, 20), 5731 IK-34 (1, 13), 5743 IK-38 (2, 1822), 5750IK-40 (1,20), 5761IK-42 (1,16). GULF STREAM: MCZ 62317 (1, 17), 62318 (1, 26). GULF OF MEXICO: ANSP 156154 (1, 12). YUCATAN CHANNEL: ANSP 157626 (1, 10).

Unidentified Saccopharyngoid Leptocephalus Figure 898 Saccopharyngiform larva. Castle and Raju, 1975: 18, fig. 7.

Distinctive Characters. This leptocephalus resembles those of Saccopharynx and Eurypharynx in its deep body, large mouth, and thickened intestine covered with small melanophores. It differs, however, in several ways. Its mouth is enlarged by a posterior extension of the jaws rather than an exaggerated elongation of the suspensorium, the gape is thus horizontal rather than oblique; the teeth are very short. The eye is large and very near the tip of the snout. The other Saccopharyngoid leptocephali have nearly symmetrical bodies with both the dorsal and

952

Fishes of the Western North Atlantic, Part 9

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FIGURE 898. Unidentified saccopharyngoid leptocephalus: ZMUC Dana 1322, 40 mm TL, Sargasso Sea (from Castle and Raju, 1975: fig. 7). a. Lateral view. b. Head region, c. Posterior region of intestine, d. Region of liver. Abbreviations: a, anus; af, anal fin; al, anterior liver lobe; ba, branchial aperture; gb, gall bladder; h, heart; i, intestine; m, intestinal melanophore; o, oesophagus, pi, posterior liver lobe; s, stomach; t, thymus; ub, urinary bladder; vbv, last visceral blood vessel.

ventral outlines convex. In the present leptocephalus the ventral outline is nearly flat while the dorsal profile is strongly convex. Unlike the leptocephali of the other two genera, the intestine is much longer than the esophagus. Description (from Castle and Raju, 1975: 18). Total myomeres 105 (n = 1), preanal myomeres 62 (1), predorsal myomeres ca 73 (1), LVBV myomeres 52 (1), prepectoral myomeres 6 (1), anterior

margin of liver at myomere 14 (1), dorsal-fin rays ca 150 (1), anal-fin rays 100 (1). Body deep, highly convex dorsally, nearly flat ventrally. Tail acute, no caudal fin visible. Myomeres V-shaped. Gut without loops or convolutions, preanal length between two-thirds and three-fourths TL. Intestine about 3.5 times length of esophagus; posterior two-thirds to one-half of intestine markedly thicker than anterior part of

Saccopharyngoid Leptocephali

953

FIGURE 899. Monognathus (from Raju, 1974a: fig. la,b): SIO 60-241, 42 mm TL, central North Pacific (upper) and SIO 60-276, 48 mm TL, central North Pacific (lower).

intestine and esophagus. Dorsal fin begins slightly behind level of anus. Pectoral fin present, located low on side of body, relatively far behind head, its base below sixth myomere. Mouth large, terminating far behind eye. Suspensorium modestly elongate, directed slightly posteriorly; gape horizontal. Eye large, close to tip of snout. Snout very short. Teeth short, present on upper jaw only. Four inconspicuous gill arches. Pigmentation. Small melanophores scattered over posterior half of intestine. No other pigment. Size. The only known specimen is 40 mm TL. Identification. The overall structure of this leptocephalus suggests that it is a saccopharyngoid of some kind, although it differs in many ways from the leptocephali of Saccopharynx and Eurypharynx. Castle and Raju (1975: 19) concluded that it is "the larval stage of an as yet undescribed genus of Saccopharyngiformes, having affinities with the Monognathidae." They pointed out the low vertebral and fin-ray counts in known monognathid species and saw a resemblance in the shape of the skull to Monognathus bruuni. The metamorphic monognathids described by Raju (1974a: fig. la,b) have large lateral melanophores, however, which the present leptocephalus does not. Distribution. The single known specimen was

collected in the eastern Sargasso Sea (ZMUC Dana 1332 XIV). Study Material. None.

Monognathus species Figure 899 The only monognathid leptocephali known are one or two metamorphic specimens of 42-48 mm TL described by Raju (1974a: 553, fig. 1A,B). They are still semi-leptocephaloid in shape, with the deepest point at or just behind the anus. The gut retains the thickened, slightly looped or convoluted intestine characteristic of other saccopharyngoid leptocephali, sprinkled with small melanophores. The anus is slightly before midlength. The most conspicuous feature is the series of five or six large, expanded melanophores along the midlateral line. A series of smaller melanophores occurs on the ventral margin of the body beginning just behind the anus and extending a moderate distance posteriorly. A similar series of melanophores occurs on the dorsal margin, beginning near the posterior end of the ventral series. Raju's specimens came from the central and eastern Pacific. Adult and juvenile monognathids

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Fishes of the Western North Atlantic, Part 9

are now known from both the eastern and western Atlantic. If the leptocephali of these species have the large lateral melanophores character-

istic of the Pacific forms, they should be easily recognized. So far, however, such leptocephali have not been found.

Order Notacanthiformes Leptocephali DAVID G. SMITH Characters. Large to very large leptocephali, maximum SL 1 to 2 meters. Body extremely elongate, deepest in anterior half, narrowing and becoming almost threadlike posteriorly. Myomeres V-shaped, very numerous, 300 or more. Gut long and simple, anus near tip of tail. Caudal fin absent, instead a single filament trailing behind end of body. Dorsal fin short-based, approximately 8-10 rays, located at about anterior one-sixth to one-fifth SL. Anal fin occupies space between anus and end of notochord. Pectoral fin present but small, located near level of esophagus and immediately below second to fourth myomere. Pelvic fins minute, present only on larger specimens, located anterior to level of dorsal fin. Head variable, snout long or short, eye round or vertically elongate. A series of somatic melanophores along gut, variable in size and number. Sometimes small melanophores laterally on myosepta. Aside from the extreme elongation of the body, notacanthiform leptocephali resemble those of eels in general appearance. Indeed, they were treated as eel leptocephali for many years until their true identity was established. The most significant differences are the presence of pelvic fins, the short-based dorsal fin, and the caudal structure. Pelvic fins, of course, are not present on eel leptocephali at any stage of development. They are absent on small notacanthiform leptocephali as well, but long before metamorphosis begins, small pelvic-fin buds appear on the anterior part of the body somewhat before the level of the dorsal fin. The dorsal fin of eel leptocephali can be long or short, but it is always continuous

with the caudal and anal fins. In notacanthiform leptocephali, the dorsal fin is short-based and located anteriorly, far from the tip of the tail (Fig. 900). All eels except some ophichthids have a small caudal fin that is continuous with the dorsal and anal fins. The caudal structure of notacanthiform leptocephali is much different (Fig. 901). One or two structures are present that could be rudimentary hypurals, located beneath and slightly behind the posterior end of the notochord, but they are not associated with any fin rays. Instead, there is a single, thread-like filament trailing behind the body. This filament may be a modified caudal-fin ray, but it is not closely associated with either the supposed hypurals or the notochord. Composition. Three basic groups of notacanthiform leptocephali are recognizable, distinguished primarily by the shape of the head and eye. The form described as Tilurus gegenbaueri by Kolliker (1853) has a short head and a normal, round eye. Roule (1911) described a related form, called Tiluropsis, which has a short head and a vertically elongate eye. The third form, Leptocephalus giganteus Castle, 1959, has a normal eye but an elongate head and snout. None of these forms can be identified with certainty beyond the ordinal level. For that reason, they will be treated here under their larval names with the understanding that each probably consists of more than one species. The names employed here are those used by the original authors. In the case of Tilurus and Leptocephalus giganteus, these are legal names applied within the rules of zoological nomencla955

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Fishes of the Western North Atlantic, Part 9

Leptocephalus giganteus 390mm TL

"Tilurus"

"Tituropsis"

FIGURE 900. Leptocephalus giganteus, whole view and head, along with heads of Tilurus and Tiluropsis for comparison (from Castle, 1984: fig. 29). Arrow indicates dorsal fin.

ture. Tiluropsis, on the other hand, was intended by Roule simply as a convenient label for an otherwise unidentifiable leptocephalus. D'Ancona (1928: 117-118) brought both Tilurus and Tiluropsis into the binominal system by treating them as species of Leptocephalus. The names will be used here in the same sense that Roule used them: as convenient categories but without reference to a precise genus or species.

Tilurus gegenbaueri Kolliker, 1853: 100 (original description, Mediterranean, holotype unknown). Tilurus trichiurus. Kaup, 1856b: 145, pi. 16, fig. 5. Stromman, 1896: 45. Oxystomus hyalinus. Facciola, 1882: 187, pi. 7, fig. 1. Tilurus hyalinus. Facciola, 1883b: 199. Tilurus. Roule, 1913: 19. Castle, 1969c: 10. Smith, 1970: 2, 8; 1979: 35. Leptocephalus tilurus D'Ancona, 1928a: 117; 1931:142, figs. 139-142.

Tilurus Kolliker, 1853 Figure 900

Distinctive Characters. Tilurus is distinguished by its short head and snout and its round eye. Description. Predorsal myomeres 45-46 (3). Proportions as % of SL: preanal 99 (1), predorsal 16 (1), head 2 (1), greatest depth 2 (1). Pigmentation. Larger specimens have a series of spots along the ventral margin about every 23 myomeres; spots consist of numerous small

(?)Oxystomus hyalinus Rafinesque, 1810b: 62 (original description, Sicily, holotype unknown). Identity uncertain; genus preoccupied by Oxystomus Fischer de Waldheim, 1803, Mammalia. (t)Leptocephalus trichiurus Cocco, 1829: 138 (original description, Strait of Messina, holotype unknown).

Leptocephalus gegenbaueri. Castle, 1969c: 40.

Notacanthiform Leptocephali

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