BIOLOGICAL INVESTIGATIONS OF THE DEEP SEA. 44. XENOCONGRID EEL LARVAE IN THE WESTERN NORTH ATLANTIC1
DAVID G. SMITH Institute of Marine Sciences, University of Miami
ABSTRACT The leptocephalous larvae of the eel family Xenocongridae in the west- ern North Atlantic Ocean are identified and characterized. They are shown to form a compact and relatively uniform group. Larvae of six of the seven known western Atlantic species were found. Chilorhinus suensoni and Kaupichthys hyoproroides were common, while Kaupichthys nuchalis, Chlopsis bicolor, Robinsia catherinae, and Catesbya pseudomuraena were rarer. No leptocephali of Chlopsis dentatus were found. Although other authors have placed Chilorhinus as a separate family, the morphology of the larva suggests that it is a typical xenocongrid, and it is so treated. Lep- tocephalus hyoproroides Stromman is shown to be the larva of Kaupichthys diodontus (including K. at/anticus), and is accepted as the valid name of the species. The nomenclatural problem raised by the priority of names based on leptocephali is discussed. Keys to the xenocongrid eels of the western North Atlantic, both larvae and adults, are given. Station data and counts and measurements are given for all specimens, and each species is illustrated.
INTRODUCTION The eel larvae or leptocephali are among the most conspicuous and char- acteristic components of tropical and subtropical plankton, yet they remain relatively poorly known. This is correlated with the uncertain taxonomy of the adults. The literature on eel taxonomy is widely scattered and much of it, especially the older works, is inadequate. The current need is for comprehensive treatment of eel families covering both larvae and adults. This report is an attempt to summarize the larvae of one family, the Xeno- congridae, in the western North Atlantic. The tropical western North Atlantic is an area well suited to studies of this sort. In the richness of its marine fauna it is second only to the vast tropical Indo-Pacific region. In addition, its boundaries are well defined, both geographically and faunistically. Much of the material reported on here was collected in the Straits of Florida, a particularly favorable area of study. The Florida Current flows within a few miles of the coast near Miami, providing easy access to oceanic plankton. The area has been in- tensively collected by the Institute of Marine Sciences of the University of
1Contribution No. 1018 from the Institute of Marine Sciences, University of Miami. This paper is one of a series resulting from the National Geographic Society-University of Miami Deep-Sea Biol- ogy Program. This stUdy is part of a thesis presented to the faculty of the University of Miami in partial fulfillment of the requirements for the degree Master of Science. 378 Bulletin of Marine Science [19(2) Miami over the past several years, and a sizeable collection of leptocephali has been accumulated. The water of the Florida Current comes partly from the Gulf of Mexico and the Caribbean Sea and partly from the open Atlantic, so it likely contains larval representatives of all the western North Atlantic eels. Even those species which normally occur only along the South American coast will occasionally be carried north into the Gulf Stream. The recognition of a large series of xenocongrid eel larvae coincided with the discovery of important new information on xenocongrid adults. The opportunity was present for the first time to identify and characterize the leptocephali of the xenocongrid eels of the western North Atlantic.
ACKNOWLEDGMENTS This report stems from a program of research on oceanic fishes sup- ported by the National Science Foundation (NSF-GB-1350, GB-4389, GB- 70 15x), C. Richard Robins, principal investigator. Much of the material collected from the Research Vessels PILLSBURYand TURSJOPSwas obtained through grants NSF-G-23745 and GB-893 from the National Science Foun- dation to Dr. Donald P. de Sylva. Ship-time support was through NSF-GB- 1204, while travel and equipment was provided by the National Geographic Society-University of Miami Deep-Sea Biology Program. I wish to thank Dr. C. Richard Robins of the Institute of Marine Sci- ences for his encouragement and guidance throughout the course of this study. Drs. Frederick M. Bayer of the Institute of Marine Sciences and William J. Richards of the Bureau of Commercial Fisheries Tropical At- lantic Biological Laboratory reviewed the manuscript, and William N. Eschmeyer, now of the California Academy of Sciences, provided additional suggestions and criticisms. I have profited from discussions about eels and eel larvae with David M. Dean of the Institute. Finally, I extend a special word of appreciation to Dr. James E. Bohlke of the Academy of Natural Sciences of Philadelphia, without whose assistance and cooperation this study could not have been completed.
MATERIAL Collections.-A total of 136 specimens of xenocongrid leptocephali was found in the collections of the Institute of Marine Sciences. These have come from various collecting operations carried out over a period of 14 years. The largest segment of the material (Table 1) stems from the work on oceanic fishes of the Florida Current carried out aboard R/V GERDA. The material from the R/V PILLSBURYwas taken on two cruises. Stations 100-191 were made on a cruise from Miami to Bermuda, and stations 343- 475 were run between Panama and Trinidad. The SL (scattering layer) 1969] Smith: Xenocongrid Eel Larvae 379
N N \D \D 0'\- 0'\- () () o 0'\ o 00 N r"l 00 v Irl 0'\ r"l 00 r- o o Irl r"l r-- r- \D 00 r- 00 Irl I I I I v I I 00 r- Irl 0'\ r- \D- 00 Irl r- oo 0'\ oo r"l o r- r- Irl r- r- 00 0\0 00 Vlrl NN o 0 00 0'\0'\ 0000 r-r- \000 MN o 0 Irllrl NN -< o ~Q:; o 380 Bulletin ot Marine Science [19(2) .•...... v) v) V) \0 \0 \0 \0 \0 \0 \0 0\- 0\ 0\- 0\- -0\ d •.....•o:l V) N o 00 00 000 o OOV)V)N 0\ t"'- t"'- MO v) N\O- - o v) I o 6 ;26 V) 6 00 - 00 ' 00 00 t"'- 0\0\ 0\ 0\ 0\ N NOO N o ' NN M \:ooOe-V) 'I""""l.,....,oj V M NN 0 "" "" - t-- DOD ?~?~? ~~ ~ ~ v) v) \0 O-O-N NN N N NN N MMMMM O\Ot"'-\OOO OOO-N- - - 1969] Smith: Xenocongrid Eel Larvae 381 f- oiJoiJoiJ>. -<-<-<~::l ::l ::l ~ 0\000 00\ 00 '~--l __ 1"1 N 1"1 00 o 00\l"'l0 o o 00 o 00 1"1 .1"10 I'- N "'0 <') 00 '" o '" ' 1"1- 00 _00 o 0\ 1'-- o _I 0\ -1"1 - -~-I'- iil.-n 010\ ~~~Oo r-. Ooil; --+ 00 \0 .q: ~ 0\00 Oob 00000\"';...0 ~ In --+ ...o..,f l"'l0-<')<') ~--+I"""""IN--+ 0", 1"1 "''''o 0 "''''o 0 00000 o 0 0 o 0 ~;;" 00 ~t-.. 0\ 0\ 0\ 00 00 1"1_ 0\ --0\0\ I'- I'- I'- I'- I'- "''''1'-1'- "''''1'-1'- I'- I'- I'- \0 \0 \0 \0 I'- 1'-1'- Nil; ~N 0100 NiI;~ 0001 ,,",iI; 0100 b '" ~ f'i vi ai."t ."t."t 00 ci 00 air--: ci -0 00 vi."t ("fjNN-I~ -1"1 1"11"1 <') <') '" ' 1'-1"1 -0V)- 382 Bulletin of Marine Science [19(2) N r--Nr'lr'lr'lr'l \0 Ir>lrllr>lr>lr>lr> 0\ 0\0\0\0\0\0\ ...... ,- --I •••••• Q) Q) c::: c::: ~~.o ::I :::l ::I ::I Q) ~ti~~~~ ....., ....., .....,.....,u., ~O~u.,u.,u., 0\ o NNO r--r--N\O\Or-- N N N N-NNNN 00 o o o 00 o N o •....• r'l l' N N ' o o of-< of-< f-< f-< ~ ~ Z o oZ 1969J Smith: X enocongrid Eel Larvae 383 MMMoooo V)V)V)V)\r) 0\0\0\0\0\ '1"""'1. .,...... ,.-\ T""""l OJ ~ ~:>(.):>,(.) (.) (.) OJ OJ Cl ~ZO~O Q Q O\r)O _ o o N -NN N N 0\'- 0'- - N ~ M ;r, ;r, N ;r, N ;r, N 00 ~~~~(,lN NN N ~~ ~ r-0\ 0\r- r-0\ 0\r- '"r- r-'" r- r- r- MV) M" _MNMt':l cJU 00 " METHODS Measurements.-Measurements were made with dial calipers and, except for standard length, were taken to the nearest tenth of a mm. Since many specimens tend to be wrinkled or misshapen, standard length could not ac- curately be taken in most cases beyond the nearest mm. STANDARDLENGTH(SL): tip of snout to base of caudal fin (end of hypural). This was chosen instead of the commonly used total length, which includes the caudal fin. SL is easier to measure and it seems a more fundamental unit not dependent upon a largely irrelevant and easily dam- aged structure such as the caudal fin. 1969] Smith: Xenocongrid Eel Larvae 385 PREANAL LENGTH: tip of snout to anus. HEAD LENGTH: tip of snout to base of pectoral fin. GREATEST DEPTH: depth of body at deepest point, usually a short dis- tance behind anus. CountS.-TOTAL MYOMERES: all myomeres, including the few anterior- most ones that are not continued below the midline. PREANAL MYOMERES: those myomeres back to and including the one directly above the anus, measured on the midline. PREDORSALMYOMERES: those myomeres back to and including the one directly below the origin of the dorsal fin, measured on the midline. POSITION OF THE VERTICAL BLOOD VESSELS: measured at the level of the notochord where they join the aorta. NUMBERS OF VERTEBRAE: in the adult eels, were counted on x-rays of specimens in the collections of the Institute of Marine Sciences. All verte- brae were counted, including the hypural. Terminology.-A number of terms have appeared in the literature to de- note various growth stages of leptocephali, most of which are purely arbi- trary. In fact there are only three stages in the pelagic life of a young eel which are qualitatively distinct, and these are the only terms which will be used in this work. They are: ( 1) premetamorphic larvae, denoting all larvae before the beginning of metamorphosis; (2) metamorphosing larvae; and (3) glass eel, referring to the stage which has completed metamor- phosis but has not yet acquired the pigmentation of the adult. A notochord runs the length of the body about midway between the dorsal and ventral margins. At this level the dorsal and ventral portions of the myomeres meet and form an angle. The line formed by the angles of the myomeres will be referred to as the midline. FAMILY XENOCONGRIDAE The Xenocongridae is a family of small eels inhabiting relatively shallow tropical and subtropical seas. These eels form a rather uniform group that seems to be closest to the morays, the Muraenidae, but xenocongrids lack many of the specializations of the muraenids. As with most eel families, it is difficult to find a single conspicuous iden- tifying character that is both inclusive and exclusive. Xenocongrids are probably characterized best by a combination of the reduction of the lat- eral-line pore system and the position of the posterior nostril. The lateral- line pores on the body are obsolete and those of the head are reduced as follows. The supraorbital series contains two pores, both well forward on the snout. The suborbital series contains five pores: two under the eye be- hind the posterior nostril, two between the anterior and posterior nostrils, 386 Bulletin of Marine Science [19(2) and one in front of the anterior nostril. The mandibular series contains either five or six pores in front of the angle of the jaw and sometimes an extra one behind it. In the branchial region anterior to the level of the gill opening there are one or two pores. The only other eel family which shows this pattern is the Muraenidae, and its members can be distinguished by the posterior nostril, which is always high on the head around the level of the upper margin of the eye. All xenocongrids except one have the pos- terior nostril opening into the lip. Kaupichthys nuchalis, the exception, has its posterior nostril located laterally, in front of the middle of the eye. Dysommina (family Dysomminidae) also has a reduced pore system and bears a superficial resemblance to some xenocongrids, but it has a lateral posterior nostril and an extra supraorbital pore located immediately behind the anterior nostril. The rare Myroconger (family Myrocongridae, known only from the holotype) is also similar, but it has the high posterior nostril found in the morays (Robins & Robins, 1966:123). Bohlke (1956) has characterized the family Xenocongridae, summa- rized the literature concerning it, and reviewed its constituent species. There are 14 currently recognized species of xenocongrid eels, seven of which occur in the western North Atlantic. Several of the species are very poorly known, some from single specimens, and it is certain that more species await discovery, particularly in the Indo-Pacific. The western Atlantic spe- cies represent five genera: Chlopsis, Kaupichthys, Chilorhinus, Robinsia, and Catesbya. For a complete account of the western Atlantic species see Bohlke (1956, 1966), Robins & Robins (1967), and Bohlke & Smith (1967, 1968). KEY TO THE ADULT XENOCONGRID EELS OF THE WESTERN NORTH ATLANTIC A. Pectoral fin well developed; 6 mandibular pores in front of angle of jaw B B. Posterior nostril labial C C. 2 branchial pores; teeth moderate; vertebrae 110-120 _ ____. ._ __._.______Ka up ich thy s hyo proroide s* CC. 1 branchial pore; teeth long, slender; vertebrae 137-141 ____. . . .__.______Cates byap seudo murae na BB. Posterior nostril lateral Kaupichthys nuchalis AA. Pectoral fin absent, or at most a fleshy tab without well-developed rays; 5 mandibular pores in front of angle of jaw ._...... _.D • Includes Kaupichthys atlanticus Bohlke and K. diodontus Schultz; see J. L. B. Smith (1965b) and Bohlke & Smith (1968). 1969] Smith: Xenoeongrid Eel Larvae 387 D. Posterior nostril opens inside confines of mouth; lower lip with downwardly directed flange Chilorhinus suensoni DD. Posterior nostril labial but outside mouth; no flange on lower 1iP ------_____ E E. Vomerine teeth in 2 series. Chlopsis F F. Body longitudinally bicolored, dark above and pale below Chlopsis bieolor FF. Body yellowish with irregular transverse brown bands Chlopsis dentatus EE. A single series of compressed teeth on vomer; body bi- colored _ Ro binsia eatherinae XENOCONGRID LEPTOCEPHAU Deseription.-Moderate to small leptocephali, usually less than 100 mm. Body rather deep, 11-37 per cent of SL. Angle which myomeres make at midline quite obtuse. Gut a simple, straight tube without loops or thicken- ings. Gut short, 39-59 per cent of SL, generally relatively longer in young specimens. Dorsal fin long, originating at 14th-27th myomere. Liver pres- ent as a thickening surrounding gut anteriorly, posterior margin at about 15th myomere. Gall bladder a small oval mass lying on dorsal surface of gut at about 14th myomere. Kidney a simple tube along top of gut ending at or slightly behind vent, except Kaupiehthys nuehalis in which it ends some distance in front of vent. Vertical blood vessels 3 to about 7: gen- erally one anteriorly at myomere 11-14, one shortly before vent near myo- mere 42-47, and one originating from end of kidney near myomere 50-55; in addition, up to 5 intermediate blood vessels may be present. Teeth vari- able: anteriormost tooth in each jaw appears to originate from a point slightly outside tip of jaw; this tooth followed in upper jaw by about 4-8 large teeth and 6-19 small teeth, in lower jaw by 4-9 large teeth and 3-4 small teeth. Pigmentation variable; there is no underlying pattern common to all species, although there is often a patch of pigment immediately below iris, a feature found also in certain congrids (Castle, 1964). Diagnosis.-Leptocephali of the Xenocongridae are distinguished from those of all other eel families by the short, simple gut. The only other lep- tocephali in which the gut is as short as half the SL or less, those of the Nettastomidae and some ophichthids, have characteristic swellings and/or undulations of the gut. The relatively deep body, long dorsal fin, and open- angled myomeres further characterize xenocongrid larvae which, altogether, form a rather compact and easily recognized group. History.- The first leptocephalus recognized as belonging to one of the species now placed in the Xenocongridae was that of Chlopsis bieolor, de- 388 Bulletin of Marine Science [19(2) scribed by Schmidt in 1912. Orton (1964) noted the general similarity of Stromman's Leptocephalus hyoproroides to C. bicolor and, in the light of the new knowledge of the family (Bohlke, 1956), proposed that this type of larva was representative of the Xenocongridae. A full account of the literature will be given below under the species concerned. Distribution and Abundance.-Xenocongrid leptocephali have been re- corded from the western Atlantic, eastern Atlantic (B1ache, 1964; Castle, 1966), eastern Pacific (Garman, 1899; Orton, 1964), and western Pacific (Castle, 1964; Orton, 1964). Xenocongrid larvae form a major constituent of the leptocephalus fauna in the western North Atlantic. In the collections of the Institute of Marine Sciences they are exceeded in number only by the Congridae, Ophichthidae, AnguilJidae, and Muraenidae. The dominant types here are Chilorhinus and Kaupichthys, while in the eastern Atlantic and eastern Pacific the ehlapsis type seems dominant. In the western Atlantic the abundance of larvae of each species corresponds to the abundance of adults: Chilorhinus suensoni and Kaupichthys hyoproroides are quite common, while the others are rare. Xenocongrid larvae are present in the plankton throughout the year. A class of distinctly smaller individuals appears in the plankton around July, a fact which at first sight suggests a distinct spawning period. An examina- tion of a large series of adults from the Bahamas and West Indies, however, revealed females with eggs to be present in all seasons. No solid evidence exists, then, to prove that xenocongrid eels have a definite spawning season. Since closing nets were not used to collect the present material, precise information is unavailable on depth distribution. It can be assumed, how- ever, that xenocongrid larvae are restricted to the near-surface levels of the ocean, as are the larvae of most other eels which have been studied. The specimens taken in deep tows were almost certainly caught at shallower depths while the net was being lowered or raised. KEY TO LARVAE OF THE XENOCONGRID EELS OF THE WESTERN NORTH ATLANTIC A. Lateral pigment scattered over entire surface of body B B. Myomeres llO-120 Kaupichthys hyoproroides BB. Myomeres 136-141 Catesbya pseudomuraena AA. Lateral pigment confined to midline C C. Lateral pigment extending for most of length; ventral pigment extending length of gut; kidney reaching to anus D D. Lateral melanophores very small E 1969] Smith: Xenoeongrid Eel Larvae 389 E. Lateral melanophores generally one per myomere, forming a single row; myomeres 97-105 ______Chilo rh inus sue nso ni EE. Lateral melanophores 2 or 3 per myomere, forming an irregular double row. Chlopsis F F. Myomeres 127-134 Chlopsis bieolor FF. Myomeres 117 (Chlopsis dentatus) DD. Lateral melanophores large, expanded, 3-16 in number; myomeres about 127-137 Robinsia eatherinae CC. Lateral pigment confined to posterior part of body; ventral pigment confined to posterior part of gut; kidney ends a short distance in front of vent; myomeres about 121-124 ______K aupieh thy s nu ehal is Genus Chlopsis Rafinesque, 1810 Diagnosis.-An oblique row of minute melanophores immediately behind articulation of lower jaw. Several melanophores in heart area. A row of melanophores ventrally running along top of gut, extending to vent. Lat- eral pigment confined to midline, beginning at about 17th myomere and extending posteriorly to within about 6 myomeres of end; at extreme an- terior and posterior end, one melanophore per myomere; for greater part of length, however, lateral pigment consists of 2 or 3 melanophores per segment, the anterior one in each myomere below level of posterior one, resulting in an irregular double line. In addition, an irregular row of mi- nute melanophores on posterior end of anal fin, extending onto caudal fin. Remarks.-Garman (1899) described Atopiehthys longidens from the eastern Pacific without attempting to identify it. Thirteen years later Schmidt identified the larva of Chlopsis bieolor from the Mediterranean, where it is quite common. Orton (1964) pointed out that the leptocephalus of C. bieolor is essentially the same animal as Garman's A. longidens and proposed that this type of larva represents a complex of closely related species. It seems likely that this group corresponds to the genus Chlopsis as now recognized. Larvae of Chlopsis have been recorded also from the western Atlantic, the Gulf of Guinea (they are common among the ma- terial collected there by the PILLSBURYin 1964 and 1965; see also Blache, 1964), the Mediterranean (Schmidt, 1912; Sparta, 1939), the Mauritanian region (Castle, 1966), and the western Pacific (Orton, 1964). Additional discussion of the literature concerning larvae of Chlopsis can be found in Orton (1964). Two species of Chlopsis occur in the western Atlantic; both are rare. Only three larval specimens are present in the collections of the Institute of 390 Bulletin of Marine Science [19(2) TABLE 2 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Chlopsis bie%r FROM THE WESTERN NORTH ATLANTIC Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm) mm %SL mm %SL mm %SL meres meres meres Stage GERDA 284 44 18.3 42 4.5 10 10.2 23 127 46 23 pl GERDA 463 44 18.0 41 5.3 12 6.5 15 128 43 14 M~ PILLSBURY 191 53 21.8 41 4.5 9 14.0 26 129 47 20 P 1 P = premetamorphic. oM = metamorphosing. Marine Sciences; all three belong to one species. This is in sharp con- trast to the eastern Pacific and eastern Atlantic where larvae of Chlopsis are common. Chlopsis bie%r Rafinesque, 1810 Fig. 1 Diagnosis.-Myomeres ]27-129. Remarks.-This oldest known species of xenocongrid eel was, until re- cently, known only from the Mediterranean. It has since been recorded from West Africa (Blache, 1964; Castle, 1966) and the western Atlantic (Robins & Robins, 1967; Bohlke & Smith, ]968). Vertebral counts re- corded in the literature are 131-136 from the Mediterranean and 127-134 from the western Atlantic. The three larvae have myomere counts of ] 27, 128, and] 29 (Table 2) and must, therefore, belong to this species. The scarcity of Chlopsis bieolor in the western Atlantic in contrast to its abundance, indicated by larval material, in the eastern Atlantic is difficult to explain, and is one of the peculiarities of the zoogeography of xeno- congrid eels. Chlopsis dentatus (Seale), 1917 Diagnosis.-Myomeres 116-117. Remarks.-No leptocephali have yet been found which can be identified with this species. Considering the close morphological similarity of the adult to the adults of other species of the genus, it can be assumed that the larva is of the typical Ch/opsis sort. Therefore, we have to look for a Chlopsis larva with a myomere count of around 117. Ch/opsis dentatus is probably completely separable from C. bie%r on the basis of vertebral number. 1969] Smith: Xenocongrid Eel Larvae 391 ~ ~ ~ ~ ~ ~ 392 Bulletin of Marine Science [19(2) This is an extremely rare species, known from only four specimens in the western Atlantic. The absence of larvae indicates that this scarcity is real, and not merely an artifact of collecting. It was a great surprise recently to discover four specimens of this species among material collected in the Indian Ocean (Bohlke & Smith, 1968). This presents the strange picture of a species known from four specimens in the western Atlantic, four specimens in the Indian Ocean, and nothing in between. Genus Chilorhinus Ltitken, 1852 Diagnosis.-Almost identical to ChLopsis except that the lateral pigment is usually restricted to a single melanophore per segment. Remarks.-Chilorhinus is in many ways the most specialized of the Xeno- congridae. It is rather surprising that the larvae should be so similar to those of ChLopsis, a genus which differs markedly as an adult. The difference be- tween the larvae, though slight, is usually consistent enough to permit iden- tification without the need to count myomeres. J. L. B. Smith (1965a, ]965b) has recently suggested that Chilorhinus should be removed from the Xenocongridae and placed in a family of its own, or at least in a dis- tinct subfamily (1966). The strong similarity of its larvae to those of other xenocongrids, however, opposes this view and supports Bohlke (1956) and Robins & Robins (1967) who retained it in the Xenocongridae. There are two currently recognized species of ChiLorhinus: C. suensoni in the western Atlantic and C. pLatyrhynchus (Norman) in the Indo-Pacific. They are distinguished only by the number of vertebrae, 97-] 05 in C. suen- soni and 107-112 (based on two specimens) in C. pLatyrhynchus. Recent information on the relation between western Atlantic and Indo-Pacific spe- cies of other xenocongrid genera (J. L. B. Smith, 1965b; Bohlke & Smith, 1968) suggests that the status of these two nominal species may warrant reexamination. ChiLorhinus suensoni Liitken, ] 852 Fig. 2 Diagnosis.-Myomeres 97-105. ldenti{ication.-ChiLorhinus suensoni is one of the two common spe- cies of western Atlantic xenocongrids, and the present larva is one of the two common xenocongrid leptocephali. Table 4 shows the distribution of myomere counts of 44 larvae against the distribution of vertebral counts of 50 adults given by Bohlke (1956). There is perfect agreement. The pres- ence of transitional specimens confirms the identification. Remarks.-Fowler (1944) described LeptocephaLus feathersi from the Caribbean Sea near Old Providence Island, off Nicaragua. He commented 1969] Smith: Xenocongrid Eel Larvae 393 rn ::: 0;; ..c p. (l) o() p. (l) ....l 394 Bulletin of Marine Science [19(2) TABLE 3 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Chi/orhinus suensoni FROM THE WESTERN NORTH ATLANTIC Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm) mm %SL mm %SL mm%SL meres meres meres Stage GERDA 84 35 17.6 50 3.9 11 9.4 27 ca. 100 46 22 pl GERDA 85 40 19.0 48 4.3 11 11.7 29 100 43 23 P GERDA 344 23 12.8 56 2.7 12 6.1 27 ca. 98 42 P GERDA 345 22 12.4 56 2.7 12 6.0 27 ca. 100 ca. 42 P GERDA 351 36 17.2 48 3.5 10 9.6 27 98 43 23 P GERDA 351 23 12.3 53 2.7 12 7.1 31 45 P GERDA 351 23 12.0 52 2.4 10 7.3 32 100 44 P GERDA 351 23 12.0 52 2.4 10 6.2 27 ca. 100 45 P GERDA 351 26 13.8 53 2.6 10 6.7 26 ca. 100 44 24 P GERDA 351 22 12.4 56 2.3 10 6.0 27 47 P GERDA 351 24 12.7 53 2.9 12 6.4 27 44 P GERDA 358 45 22.0 49 4.7 10 13.4 30 100 44 22 P GERDA 497 35 17.7 50 3.5 10 8.6 25 100 44 20 P GERDA 541 36 16.8 47 4.3 12 10.4 29 99 43 22 P GERDA 541 41 19.4 47 4.3 10 13.3 33 100 44 21 P GERDA 541 38 18.8 50 4.6 12 10.4 27 99 42 23 P GERDA 541 40 17.8 45 4.1 10 12.2 31 100 43 22 P GERDA 541 30 4.6 15 7.7 26 17 M2 GERDA 541 35 18.5 53 4.8 14 8.2 23 99 40 20 M GERDA 541 35 16.2 46 4.5 13 9.6 27 ca. 97 40 21 M GERDA 543 41 20.5 50 4.3 10 10.3 25 100 45 P GERDA 543 40 19.0 47 4.0 10 9.4 24 103 44 22 P GERDA 548 39 18.3 47 4.2 11 11.4 29 101 42 22 P GERDA 548 42 20.8 50 4.5 11 11.7 28 101 45 22 P GERDA 549 38 3.9 11 - ca. 99 41 P GERDA 772 46 22.2 48 4.4 10 14.4 31 102 45 P GERDA 778 41 19.1 47 3.8 9 13.5 33 98 40 21 P TURSIOPS 107 44 21.1 48 4.7 11 12.3 28 99 41 20 P TURSIOPS 152 33 16.1 50 3.5 11 10.0 30 101 45 21 P TURSIOPS 152 16 9.2 57 2.1 13 4.8 30 ca. 98 44 P TURSIOPS 157 24 12.7 53 2.7 11 6.8 28 102 44 P TURSIOPS 157 17 9.3 55 2.2 13 5.5 32 ca. 100 43 P PILLSBURY 106 40 19.0 48 4.1 10 -ca. 99 ca. 44 P PILLSBURY 160 39 19.3 50 4.3 10 12.1 33 102 46 21 P PILLSBURY 162 46 22.2 48 4.5 10 17.2 37 99 45 23 P PILLSBURY 162 27 13.8 51 2.7 10 8.8 33 98 43 P PILLSBURY 170 44 20.3 46 3.9 9 13.2 30 99 44 23 P DdeS 370 40 17.9 45 5.1 13 18.4 46 ca. 99 42 20 M Sup!. 168 42 20.7 49 4.3 10 14.3 34 101 45 22 P TOTO T-2 37 17.1 46 4.1 11 11.5 31 101 22 P TOTO T-3 35 17.0 49 3.7 11 11.3 32 101 46 24 P TOTO T-5 42 20.7 49 4.3 10 12.8 30 98 46 22 P TOTO T-5 42 20.0 48 4.3 10 14.2 34 101 43 20 P TOTO T-5 40 18.9 47 3.8 10 11.6 29 104 46 23 P TOTO T-5 40 20.2 50 4.3 11 12.8 32 98 45 22 P TOTO T-6 46 22.0 48 4.2 9 14.8 32 101 45 21 P TOTO T-7 39 19.6 50 3.9 10 8.5 22 99 45 23 P 1 P = premelamorphic. , M = metamorphosing. 1969] Smith: Xenocongrid Eel Larvae 395 TABLE 3 (CONTINUED) Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm) mm %SL mm %SL mm %SL meres meres meres Stage TOTO T-7 41 19.5 48 4.2 10 11.4 28 100 44 20 P TOTO T-7 39 19.3 50 4.0 10 9.0 23 99 45 20 P TOTO T-7 39 19.2 49 4.2 11 12.4 32 ca. 101 45 23 P TOTO T-7 39 19.6 50 4.5 12 11.1 28 99 45 27 P TOTO T-7 38 ]6.8 44 3.5 9 9.8 26 ]04 47 25 P TOTO T-7 4] 19.5 48 4.5 11 ]2.3 30 104 44 23 P TOTO T-lO 40 ]9.4 49 4.1 10 ]0.7 27 101 43 21 P ONRTOTO 8-3 25 13.3 53 3.1 12 7.6 30 103 45 P ONRTOTO 11-3 41 19.0 46 4.4 11 12.8 37 102 42 22 P ONR TOTO 11-3 42 20.0 48 4.2 ]0 13.2 3] ]00 42 20 P ONRTOTO 13-3 43 20.0 47 4.7 11 13.4 31 ca. 100 ca. 40 22 P SL 13 A-8 38 18.2 48 3.9 10 10.7 28 97 44 22 P SL 22 C-3 26 14.3 55 2.9 11 7.3 28 100 44 P SL 23 A-2 37 18.9 51 4.2 11 ]2.2 33 ca. 101 ca. 45 P on its resemblance to L. hyoproroides Stromman without attempting to identify it with an adult. Examination of the holotype at the Academy of Natural Sciences of Philadelphia reveals it to be a specimen of Chilorhinus suensoni at the beginning of metamorphosis. There are some discrepancies between Fowler's description and the specimen itself. He stated "Myo- tomes 70 (30 + 40)," whereas the specimen has about 100-105. He de- scribed the lateral pigmentation as one pigment spot per myomere, whereas in the type some myomeres have more than one. He also described the dorsal fin as beginning about halfway between the head and tail instead of anteriorly as in all xenocongrids. Without seeing the holotype, Leptoceph- alus feathersi would have been difficult to identify. Genus Kaupichthys Schultz, 1943 Diagnosis.- Two western Atlantic species are currently assigned to this genus. The larvae are quite different, and will be characterized separately below. TABLE 4 DISTRIBUTION OF NUMBER OF VERTEBRAE IN ADULTS AND MYOMERES IN LARVAE OF Chilorhinus suensoni FROM THE WESTERN NORTH ATLANTIC No. of vertebrae or myomeres 97 98 99 100 10] 102 103 104 105 No. of Adults o 3 5 11 17 8 3 1 2 No. of Larvae 2 5 7 9 10 6 3 2 o 396 Bulletin of Marine Science [19(2) Kaupichthys hyoproroides (Stromman), 1896 Figs. 3,4 Diagnosis.-Lateral melanophores not confined to midline, but extend along myosepta to dorsal and ventral margins. Pigmentation of head simi- lar to Chlopsis and Chilorhinus, with these exceptions: melanophores on upper and lower jaws between bases of teeth; two oblique rows behind angle of jaw, instead of one. Ventral pigmentation as in Chlopsis and Chilorhinus, but also a second row of minute melanophores along bottom of gut. Myomeres 113-120. This is one of the few leptocephali of any kind with pigment scattered over the entire body. Identification.-Kaupichthys hyoproroides is the other common western Atlantic xenocongrid eel, and the present larva is the other common xeno- congrid leptocephalus. Table 6 shows the distribution of myomere counts of the 17 larvae in which accurate counts could be made against the verte- bral counts of 21 adults. Here again we see a good agreement. In addition, the counts that could only be approximated for the other larvae fall in the same range. Two metamorphosing specimens were found. One of these, from GERDA station 499 (see Tables 4 and 6), is a glass eel which has already assumed the definitive adult characters, but retains the full pig- mentation of the larva. Specimens at this stage are very useful in identifi- cation, but are not common since this phase is passed through rather quickly. Remarks.-There is little doubt that Stromman's Leptocephalus hyopro- roides belongs to this species (see Bertin, 1936, for additional information on the holotype). This is the earliest available name and, according to a strict interpretation of the International Code of Zoological Nomenclature, the species must be Kaupichthys hyoproroides (Stromman). The addition of names for leptocephali to the synonymies of eels is to be regretted. It opens the prospect that, with added knowledge of eel larvae, wholesale changes of established names of eels will take place, since of the scores of names that have been proposed for leptocephali many must surely antedate the names of their corresponding adults. To complicate the situation fur- ther, most described "species" of leptocephali actually represent groups of closely related species (Orton, 1964: 438). The component species of these groups can generally be distinguished only by the number of myomeres. Consequently, closely related species with similar vertebral counts cannot be distinguished as leptocephali. A good example of this situation is found among the xenocongrids of the western Pacific where there are three sym- patrie species of Kaupichthys (K. hyoproroides, K. atronasus Schultz, 1953, and K. brachychirus Schultz, 1953) with broadly overlapping ver- 1969] Smith: Xenocongrid Eel Larvae 397 ~ CJ) ::l c; ..c 0., OJ U 0 0.. ~ ...OJ c:OJ ~ ,. <:') \I) eno:l « 0 ~'" 0 •.••.:f • tnt:: 0 t:: '50 .- ...OJ E_ o:l E t:: oo:l " \t:,'-~-~ ;;..'" -E -t: \v' ~,-~c~' '-> '~ ::! I -, <::l \, ~ .....• 0 CJ) ::l c; ..c \\"~r~' 0., -< OJ U 0 0.. OJ \~ ....J <"i Pol ::>'" CJ ~ 398 Bulletin of Marine Science [19(2) (;j C ro c5 "0 ro CJ\.- CJ\ "'" o::i c'5 -<: Cl ~c:: 0 -f rf} cd .- 0 E'~ E •.. 00 "'" ~"," "1:::1 -(3•.. c•.. t:l. \;) ?-. ..::: '"?-. ~ ..::: 'i5,." ;:: <::l ::< .•.. 0 Qj TABLE 5 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Kaupichthys hyoproroides FROM THE WESTERN NORTH ATLANTIC Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm) mm %SL mm %SL mm %SL meres meres meres Stage GERDA 46 26 12.3 47 3.3 13 5.7 22 41 P' GERDA 46 28 14.0 50 3.3 12 5.7 20 41 P GERDA 53 40 17.0 43 4.2 11 8.9 22 116 41 18 P GERDA 263 38 16.2 43 4.2 11 8.8 23 116 40 16 P GERDA 314 36 13.4 37 5.1 14 5.8 16 ca. 116 30 11 M2 GERDA 332 49 19.2 39 5.0 10 9.2 19 115 41 16 P GERDA 344 24 11.3 47 2.7 11 5.5 23 ca. 118 42 P GERDA 345 14 P GERDA 345 23 11.2 49 3.2 14 5.3 23 P GERDA 350 36 16.0 45 3.8 15 7.4 21 ca. 116 ca. 42 P GERDA 351 16 8.6 53 1.7 11 4.0 25 41 P GERDA 497 29 12.3 42 3.5 12 7.1 24 118 39 17 P GERDA 499 48 16.4 34 5.6 12 5.5 10 GEB TURSIOPS 152 18 10.0 56 2.5 14 5.3 29 P TURSIOPS 152 20 8.7 44 2.5 13 5.5 27 P TURSlOPS 153 30 13.3 44 3.3 11 7.1 24 118 42 P TURSIOPS 153 20 10.7 54 2.4 12 4.9 25 ca. 117 43 P TURSIOPS 157 33 14.6 44 3.6 11 7.8 24 ca. 118 41 17 P TURSlOPS 157 34 14.4 42 3.5 10 7.9 23 119 40 l4 P TURSlOPS 157 31 13.4 43 3.5 11 7.7 25 ca. 117 42 15 P TURSIOPS 157 19 10.0 53 2.6 14 6.5 34 P PILLSBURY 100 18 9.6 53 2.0 11 3.6 20 ca. 118 43 P PILLSBURY 107 13 7.7 59 2.0 15 4.7 36 42 P PILLSBURY 116 32 14.2 44 3.2 10 7.1 22 118 43 18 P PILLSBURY151 48 19.7 41 4.4 9 9.4 20 ca. 117 40 P PILLSBURY170 33 14.7 45 3.3 10 7.9 24 ca.117 43 17 P PILLSBURY190 44 17.0 38 4.3 10 10.0 23 118 40 17 P PILLSBURY 191 47 18.9 40 4.8 10 9.1 19 120 38 14 P PILLSBURY383 34 15.2 45 3.7 11 7.9 23 42 P PILLSBURY384 38 16.2 43 4.3 II 6.5 17 39 15 P PILLSBURY426 42 17.1 41 3.8 9 9.1 22 119 42 17 P PILLSBURY427 39 17.2 44 3.8 10 7.8 20 ca. 120 44 P PILLSBURY460 27 12.6 47 2.8 10 7.3 27 ca. 114 40 P SL 8 E··la 41 16.5 40 4.7 II 9.3 23 118 41 15 P SL II A-I 36 14.6 41 4.0 11 8.4 23 ca. 115 40 14 P SL 13 A-4 36 14.9 41 4.0 11 8.8 24 116 39 16 P SL 14 C-I 40 16.7 42 3.8 10 8.5 21 ca. 115 43 19 P SL 22 C-3 38 16.7 44 3.8 10 7.9 21 ca. 114 43 19 P SL 55 B-3 28 12.4 44 3.7 13 7.1 25 114 40 P SL 58 4-a 27 13.6 50 3.4 13 7.7 29 113 42 P SL 58 B-2 21 9.9 47 2.7 13 5.2 25 117 41 P SL 58 B-2 26 11.7 45 3.2 12 5.3 20 117 40 P SL 58 B-4 19 10.6 56 2.6 14 5.0 26 116 43 P SL 128 2 30 13.7 46 3.0 10 7.3 24 115 42 P SL 128 2 31 14.1 46 3.2 10 7.3 24 116 42 P Carib 20 42 17.0 41 4.6 11 7.9 19 119 40 16 P DdeS 516 24 11.6 48 2.6 11 5.7 24 40 P TOTO T-7 44 18.4 42 4.4 10 7.6 17 114 40 16 P 1 P = premetarnorphic. " M = metamorphosing. 3 GE = glass eel. 400 Bulletin of Marine Science [19(2) TABLE 6 DISTRIBUTION OF NUMBER OF VERTEBRAE IN ADULTS AND MYOMERES IN LARVAE OF Kaupichthys hyoproroides FROM THE WESTERN NORTH ATLANTIC No. of vertebrae or myomeres 110 III 112 113 114 lIS 116 117 118 119 120 No. of Adults 1 o o o o 1 4 5 5 2 3 No. of Larvae o o o 1 2 o 4 2 5 2 1 tebral counts (Bohlke & Smith, 1968). Although larvae of Kaupichthys are known from this area (Castle, 1964), it is impossible at present to tell which species they represent. The systematics and nomenclature of eels are in confusion already without this added burden. J. L. B. Smith (1965b) and Bohlke & Smith (1968) have shown that the western Atlantic and Indo-Pacific forms of this species cannot be main- tained as distinct species. Kaupichthys atlanticus Bohlke, 1956, and K. diodontus Schultz, 1943, are both synonyms of K. hyoproroides. Kaupichthys nuchalis Bohlke, 1966 Fig. 5 Diagnosis.-Lateral pigmentation inconspicuous, consisting of minute melanophores beginning roughly at level of vent and extending back to end of tail, anteriorly spaced one per 2-3 myomeres, posteriorly one per TABLE 7 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Kaupichthys nuchalis FROM THE WESTERN NORTH ATLANTIC Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm)mm %SL mm %SL mm %SL meres meres meres Stage GERDA 85 34 17.4 51 3.6 11 9.4 28 121 50 23 pl TURSIOPS 152 37 17.7 51 3.8 10 12.5 34 123 50 22 P TURSIOPS 152 26 2.9 11 6.7 26 ca. 123 P TURSIOPS 153 25 13.3 53 2.9 12 7.1 28 124 52 24 P TURSIOPS 153 26 13.0 50 3.0 12 6.4 25 121 51 P ONR TOTO 13-4 32 3.3 11 7.8 24 ca. 123 P PILLSBURY 100 26 14.0 54 3.1 12 8.7 34 122 52 P PILLSBURY 343 38 18.6 49 3.6 10 10.6 28 125 54 24 P PILLSBURY 384 38 20.0 53 3.6 10 7.0 18 124 51 P PILLSBURY 384 41 22.2 54 3.4 8 6.8 17 52 P PILLSBURY 384 39 21.7 56 3.4 9 8.3 21 123 53 P PILLSBURY 384 36 17.7 49 3.6 10 7.7 21 50 P PILLSBURY 384 35 17.3 50 4.0 II 8.9 25 ca. 122 P PILLSBURY 384 38 3.7 10 7.4 19 123 P 1 P = premetamorphic. 1969] Smith: X enocongrid Eel Larvae 401 402 Bulletin of Marine Science [19(2) TABLE 8 DISTRIBUTION OF NUMBER OF VERTEBRAE IN ADULTS AND MYOMERES IN LARVAE OF Kaupichthys nuchalis FROM THE WESTERN NORTH ATLANTIC No. of vertebrae or myomeres 120 121 122 123 124 125 No. of Adults 2 o o 1 o 1 No. of Larvae o 2 1 3 2 1 myomere. Ventral pigmentation confined to a few minute melanophores along top of posterior end of gut. Pigmentation of head consists of scat- tered melanophores, both superficial and deep. Kidney ends noticeably in front of vent. Myomeres 121-125, of which 50-54 are preanal. ldenti{ication.-No metamorphosing specimen of this species was found, but a 52-mm juvenile (UMML 23483), the smallest specimen available, showed traces of the pigmentation of the larva. The pattern-numerous melanophores on the head and none visible on the body-agrees with the larva under discussion. The myomere-vertebral counts match up well, as shown in Table 8. Kaupichthys nuchalis is the third most common xeno- congrid in the western Atlantic, and this is the third most common xeno- congrid larva. Remarks.-This larva is so different from that of Kaupichthys hyoproroides that one would expect the adults of the two species to differ considerably more than they do. The chief difference between K. nuchalis and the other species of the genus-the lateral rather than labial posterior nostril-does not seem especially profound. This nostril is Iowan the side of the head, and the upper margin has the form of an incipient flap. A slight lowering of the opening and a slight enlargement of the upper margin into a flap would result in the typical xenocongrid posterior nostril. The dentition, TABLE 9 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Catesbya pseudomuraena FROM THE WESTERN NORTH ATLANTIC Preanal Length Greatest Pre- Pre- length of head depth Total anal dorsal SL myo- myo- myo- Station (mm) mm %SL mm %SL mm %SL meres meres meres Stage SL 13 C-2 48 22.1 46 4.0 8 8.2 17 136 46 20 pl PILLSBURY384 70 28.8 41 5.5 8 7.5 11 141 49 19 P 1P = premetamorphic. 1969] Smith: Xenocongrid Eel Larvae 403 ~ '"::l -; ...c: 0.. c: "'" "'"0oj i: -.0 I'.lc.: :::> 0 ~ 404 Bulletin of Marine Science [19(2) TABLE 10 COUNTS AND MEASUREMENTS OF LEPTOCEPHALI OF Robinsia catherinae FROM THE WESTERN NORTH ATLANTIC Lateral Preanal Length Greatest melano- length of head depth Total phores •.. SL myo- P-a P-d ~b/) Station (mm) mm %SL mm %SL mm %SL meres M1 M2 Right Left Vi GERDA 351 24 11.2 47 2.5 10 5.2 22 ca. 125 43 3 6 p3 GERDA 740 25 11.6 46 2.7 11 7.4 30 127 43 8 6 P PILLSBURY 128 40 16.9 42 3.8 10 10.4 26 ca. 128 44 11 11 P PILLSBURY384 52 21.2 41 4.7 9 10.4 20 132 47 17 13 15 P PILLSBURY384 48 4.7 10 10.8 23 ca. 132 13 13 P PILLSBURY475 54 19.3 36 4.1 8 11.1 21 ca. 137 46 16 13 P ~ P-a M = preanal myomeres. 2 P-d M = predorsal myomeres. "P = premetamorphic. which has been used to characterize xenocongrid genera, is of the typical Kaupichthys pattern. This species has not been recorded outside the western Atlantic. Genus Catesbya Bohlke & Smith, 1968 Catesbya pseudomuraena Bohlke & Smith, 1968 Fig. 6 Diagnosis.-Pigmentation as in Kaupichthys hyoproroides. Myomeres 136- 141. Identification.-There is only one known species of western Atlantic xeno- congrid with a myomere count this high. In addition, the larger specimen shows the elongate form characteristic of the adult. Remarks.-When the adult of this species was discovered it was thought to belong to the genus Kaupichthys. The dentition is so distinct from that of all other species of the genus, however, that there was no choice but to place it in a new genus. Despite this, the larva is of the typical Kaupichthys type, differing only in the number of myomeres. The elongation of the head and body is apparent only in the larger specimen. This is analogous to the situation involving Ch/opsis and Chilorhinus, which differ markedly from each other as adults but are similar as larvae. The larvae of Kaupichthys hyoproroides, K. nuchalis, and Catesbya pseu- domuraena are not what would be expected from a knowledge of the adults. On the basis of adult morphology, K. hyoproroides and K. nuchalis must be grouped together and C. pseudomuraena must be separated. Among the larvae, however, C. pseudomuraena falls with K. hyoproroides and K. nucha/is is excluded. Perhaps as more knowledge is gained of the Xeno- congridae this situation will be clarified. 1969] Smith: Xenocongrid Eel Larvae 405 c FIGURE 7. Leptocephalus of Robinsia catherinae, 2S mm in SL, GERDA Sta. 740: A, entire leptocephalus; B, head; C, anal region. This is a very rare species known from only three specimens, one adult and two larvae. Genus Robinsia Bohlke & Smith, 1967 Robinsia catherinae Bohlke & Smith, 1967 Fig. 7 Diagnosis.--Lateral pigmentation a series of large, expanded melanophores along midline, 3-16 in number, often unequal on the two sides. Ventral 406 Bulletin of Marine Science [19(2 ) pigmentation about 10 large paired melanophores. Pigmentation of the head confined to a few melanophores behind jaw articulation, and a few in heart region. Myomeres about 125-137. This is the only known xenocongrid larva with large melanophores. ldenti{ication.-Again, no metamorphosing specimens were found. The vertebral count (130) of the single known western Atlantic adult is within the range of the myomere counts of the larvae. This specimen is a juve- nile which shows traces of the pigmentation of the larva consisting of a few conspicuous lateral melanophores and a ventral series of conspicuous melanophores, a pattern exhibited only by the present larvae. These facts support the identification. Remarks.-The adult of this species bears a remarkable superficial resem- blance to Chlopsis bicolor. The dentition, however, is markedly different. The single row of compressed vomerine teeth is unique among known xeno- congrids. Five adult specimens of this species are known, four from the Indian Ocean and one from the Caribbean Sea. There is nothing to indicate that the forms from the two oceans are specifically distinct. Again we have a xenocongrid eel known from the western Atlantic and the Indian Ocean, but nowhere in between. This is the third species show- ing this peculiar distribution, and Chilorhinus may prove to be a fourth. Of course, the present species and Chlopsis dentatus are rare, and it is pos- sible that either or both may eventually be found elsewhere. Kaupichthys hyoproroides, though, is a common species and shows the same pattern. The significance of this distribution and how it came about are problems which remain to be solved. SUMARIO LARVAS DE ANGUILAS XENOCONGRlDAS DE LA REGION OCCIDENTAL DEL ATLANTICO DEL NORTE Se identifican y caracterizan las larvas 1eptocefalas de las anguilas pertenecientes a la familia Xenocongridae de la region occidental del Atlantico del Norte. Se demuestra que forman un grupo compacto y reIa- tivamente uniforme. Se encontraron larvas de seis de las siete especies conocidas de la region occidental del Atlantico. Se encontro que Chilo- rhinus suensoni y Kaupichthys hyoproroides eran comunes, mientras que Kaupichthys nuchalis, Chlopsis bicolor, Robinsia catherinae y Catesbya pseudomuraena eran mas raras. No se encontro 1eptocefala de Chlopsis dentatus. Aunque otros autores han situado Chilorhinus como una familia distinta, la morfologfa de la larva sugiere que es una xenocongrida tipica y como tal es tratada. Se demuestra que Leptocephalus hyoproroides Strom- 1969] Smith: Xenocongrid Eel Larvae 407 man es la larva de Kaupichthys diodontus (incluyendo K. at/anticus) y se acepta como el nombre valido de la especie. Se discute el problema de nomenclatura que surge por la prioridad de los nombres basandose en las leptocefalas. Se dan claves para las anguilas xenocongridas de la region occidental del Atlantico del Norte, tanto larvas como adultos. Se dan datos de las estaciones, conteo y medidas de todos los ejemplares y se ilustra cada especie. LITERATURE CITED BERTIN, LEON 1936. Contribution a ['etude des larves de poissons Apodes. (Les types de Stromman a I'Institute Zoologique de J'Universite d'Uppsala). Bull. Inst. oceanogr. Monaco, No. 694: 1-16, 13 figs. BLACHE, J. 1964. Note preliminaire sur les larves leptocephales d'apodes du Golfe de Guinee. Cah. O.R.S.T.O.M., Oceanogr., 5: 5-55, 32 figs. BOHLKE, JAMES E. 1956. A synopsis of the eels of the family Xenocongridae (including the Chlopsidae and Chilorhinidae). Proc. Acad. nat. Sci. Philad., 108: 61-95,8 figs., PI. 7. 1966. The descriptions of three new eels from the tropical West Atlantic. Proc. Acad. nat. Sci. Philad., 118(4): 91-108, 3 figs. BOHLKE, JAMES E. AND DAVID G. SMITH 1967. A new xenocongrid eel from the western Indian and western Atlantic oceans. Notul. Nat., No. 408: 6 pp., 1 fig. 1968. A new xenocongrid eel from the Bahamas, with notes on other species in the family. Proc. Acad. nat. Sci. Philad., 120(2): 25-43, 3 figs. CASTLE, P. H. J. 1964. Congrid leptocephali in Australasian waters with descriptions of Conger wi/soni (BI. and Schn.) and C. verreauxi Kaup. Zool. Pub!. Victoria Univ. N.Z., 37: 1-45, 11 figs. 1966. Die ichthyologische Ausbeute der ersten westafrica-Fahrt des fischerei- technischen Forschungsschiffes "Walter Herwig." 3. The eel larvae (leptocephali). Arch. FischWiss., 17(1): 19-35. FOWLER, HENRY W. 1944. Thf: fishes of the fifth George Vanderbilt Expedition (1941). Monogr. Acad. nat. Sci. Philad., No.6: 57-529, 254 figs., 20 pIs. GARMAN, SAMUEL 1899. Reports on an exploration off the west coasts of Mexico, Central and South America, and off the Galapagos Islands, in charge of Alexander Agassiz, by the U. S. Fish Commission steamer "Albatross," during 1891, Lieut. Commander Z. L. Tanner, U.S.N., commanding. Mem. Mus. compo Zool. Harv., 24: 1-431, 97 pIs. LUTKEN, C. 1852. Nogle bemaerkninger om nasseborenes stilling hos de i gruppe med Ophisurus staaende slaegter af aalefamilien. Vidensk. Meddr. naturh. FOI·en., for 1851, Nos. 1-2: 1-21, PI. 2, Figs. 1-5. (Not seen.) ORTON, GRACE L. 1964. New information on a rare eel larva, Leptocephalus hyoproroides Stromman. Copeia, 1964(2): 434-444, 4 figs. 408 Bulletin of Marine Science [19(2) RAFINESQUE-SCHMALTZ, C. S. 18] O. Indice d'ittiologia Siciliana ossia catalogo methodica dei nome Latini, Italiano, e Siciliani dei pesci, che si rinvenogo in Sicilia. Messina, 70 pp., 2 pIs. (Not seen.) ROBINS, C. RICHARD AND CATHERINE H. ROBINS 1966. Xenoconger oiokun, a new xenocongrid eel from the Gulf of Guinea. Stud. trap. Oceanogr. Miami, 4(Part 1): 117-124, 3 figs. ROBINS, CATHERINE H. AND C. RICHARD ROBINS 1967. The xenocongrid eel Chiopsis bicoior in the western North Atlantic. Bull. mar. Sci., 17(1): 232-238, 8 figs. SCHMIDT, JOHANNES 1912. The larval form of Chiopsis bicoior Raf. Vidensk. Meddr. naturh. Foren., 64: 53-56. SCHULTZ, LEONARD P. 1943. Fishes of the Phoenix and Samoan islands collected in 1939 during the expedition of the U.S.S. Bushnell. Bull. U. S. natn. Mus., No. 180, i-x + 1-316, 27 figs., 9 pIs. 1953. Family Echelidae: worm eels. In Schultz, L. P. and collaborators: E. S. Herald, E. A Lachner, AD. WeIander, and L. P. Woods, Fishes of the Marshall and Marianas islands. Volume 1. Families from Asymmetrontidae through Siganidae. Bull. U. S. natn. Mus., No. 202: 60-83, Figs. 13-17, Pis. 8-10. SEALE, ALVIN 1917. New species of apodal fishes. Bull. Mus. compo Zool. Harv., 61 (4) : 79-94. SMITH, J. L. B. 1965a. The Indian genus Bathymyrus Alcock, 1889 with description of a new species from Vietnam. Occ. Pap. Dep. Ichthyol. Rhodes Univ. S. A, No.2: 1-11,1 fig., 1 pI. 1965b. Kaupichthys diodontus Schultz, in the western Indian Ocean, a prob- lem in systematics. Occ. Pap. Dep. Ichthyol. Rhodes Univ. S. A, No. 5: 45-54, 1 fig., PI. 12. 1966. An interesting new eel of the family Xenocongridae from Cook Is- land, Pacific. Ann. Mag. nat. Hist., Ser. 13,8(89): 297-301, 1 fig., PI. 10. SPARTA, A. 1939. Contributo alia conoscenza dello sviluppo embrionale e postembrionale nei Muraenoidi. VII. Chiopsis bicoior. Memorie. R. Com. talassogr. ital., No. 268: 1-8, 10 figs. STROMMAN, PEHR HUGO 1896. Leptocephalids in the University Museum at Upsala. Upsala, vi + 53 pp., 5 pIs.