SYNOPSIS OF THE IPNOPIDAE (PISCES, INIOMI) WITH DESCRIPTION OF TWO NEW ABYSSAL SPECIES By J0RGEN G. NIELSEN Zoological Museum, Copenhagen GILL (1884) was the first to use the family name certainty factor has been put at 0,1, between 10 % Ipnopidae. Prior to that the genus Ipnops was re- and 50 % at 0,5, and over 50 % at 1. ferred to i. a. the Scopelidae (GUNTHER1887). Four The oceanographic terms used are those proposed genera have been described, Ipnops, Bathymicrops, by BRUUN(1956 and 1957). Bathytyphlops, and Ipnoceps. The last is now con- Specimens, sidered a synonym of Ipnops (see below). The three Material examined herein : incl. type(s) genera have much in common, but they differ in Ipnops murrayi Giinther, 1878 ...... 13 certain characters which some ichthyologists con- Ipnops agassizi Garman, 1899 ...... 15 sider so important that the disagreement might Ipnops meadi n. sp. ................ 2 1 justify the establishment of separate families for each Ipnops specimens ................. 2 of the three genera (MEAD1966). However, in the Bathymicrops regis Hjort and Koefoed, present paper all the genera are referred to one 1912 .......................... 7 family only, the Ipnopidae. Bathyma'crops brevianalis n. sp. ...... 2 Family characters: Long and mostly slender Bathytyphlops sewelli (Norman, 1939) 2 fishes with a more or less depressed head and Bathytyphlops mariorzae Mead, 1958 . I flattened abdomen. The gill slits are very wide, and the anterior gill arch ends close to the symphysis of Generally, the condition of the material is rather the lower jaw. No pseudobranchs present. The poor. Very often the head is not intact, and the fin lower jaw slightly protruding. Two separate patches rays are broken. One explanation is the fragility of of vomerine teeth. The dorsal fin placed in advance these fishes, and, at least regarding those from the of the anal fin. No adipose fin. The ventral fins, "Galathea" Expedition, the gear used and the with 8 rays, are large and clasped, forming a basket depths of the localities involved that large quantities under the anus, the ovopore, and the genital papilla, of material were caught and kept in the gear for a all of which are placed much closer to the base of relatively long period. Furthermore, most of the the ventral fins than to the anal fin. Hermaphrodites specimens examined seem to have shrunk somewhat. with the testicular component lying as a small string medio-dorsally in the gonad. The number of Acknowledgments: The author is indebted to precaudal vertebrae varies from 16 to 25. The scales ROBERTH. GIBBS,Jr, BENGTHUBENDICK, N. B. are deciduous. A lateral line running along the MARSHALL,M. J. PENRITH,ALWYNE C. WHEELER, midline of the body. PETERJ. WHITEHEAD,and JOHANFR. WILLGOHS for All measurements are taken in accordance with providing material or data, to OLE MUNK for HUBBSand LAGLER(1958), except that the sym- sectioning the gonads, to H. V. CHRISTENSENfor physis of the upper jaw is used as the anteriormost taking the photographs, and to AGNETEVOLSOE for point and not the protruding lower jaw. The uro- correcting the English manuscript. Special thanks style is not included in the vertebral counts. All are given to GILESW.MEAD for lending me the morphometric characters are given in percentage of third proof of the Ipnopidae from "Fishes of the the standard length. A number in parenthesis gives Western North Atlantic, vol. 5" and to E.BERTEL- the average value for the character in question. SEN and RICHARDL.HAEDRICH for suggestions on When a character forms less than 10 % the un- the manuscript. Key to the genera of Hpnspidae: I. The dorsally directed large eyes covered by a thin, unpaired, bony membrane formed by the frontals and parietals .................................. Ipnops Giinther, 1878 (= Ipnoceps Fowler, 1943) 2. The very small eyes placed more or less laterally above the upper jaw; frontals and parietals unmodified. a. 10-14 well-developed gill rakers on first and second arches. Ventral fins well in advance of the dorsal fin ............................................ Bathymicrops Hjort and Koefoed, 1912 b. A single well-developed gill raker in the angle between the epibranchiale and ceratobranchiale. Ven- tral fins just anterior to the dorsal fin ............................. Bathytyphlops Nybelin, 1957 ent species, as the three Atlantic specimens ("Chal- Ipnops Giinther, 1878 lenger" Sts. 124 and 133) agree and correspond to Ipnoceps Fowler, 1943. all the Ipnops material known from the Atlantic Since G~~NTHERdescribed the genus very few Ocean, while the Philippine specimen ("Challenger" specimens have been reported upon, viz. : St. 198) belongs to the new species I. meadi. Specimens GUNTHER(1878 and 1887) "Challenger" 4 FOWLER(1943) described a new genus, Ipnoceps. It GOODEand BEAN(1896) "Blake" ...... 2 "differs from Ipnops chiefly in the uppermost or GARMAN(1899) "Albatross" .......... 3 simple pectoral ray with its upper edge dentated or GILCHRIST~(1 908). ................... 1 irregularly serrated". However, my examination of NORMAN(1939) John Murray Exped. ... 3 GUNTHER'Stype material showed that the large FOWLER(1943) "Albatross" .......... 3 specimen from St. 133 had the upper, long ray in MEAD^ (1 966) "Oregon" .............. 9+ ? the sinistral pectoral fin serrated in the distal fourth Present paper (1966) "Galathea". ...... 30 (PI. XV, Fig. l), a feature also found in one of the "Galathea" specimens. The reason why the serration Generic characters: is so rarely observed might be that most often parts Long and slender fishes with the frontals and of the pectoral fins are broken in the net. In all parietals forming a thin bony plate covering the other respects the two are very much alike and it eyes. A few, small teeth on the vomer and in most would be reasonable to consider Ipnoceps a syno- cases also on the palatines. Well-developed gill rakers nym of Ipnops. (Actually, it is not the upper ray in on the anterior arch and moreover relatively long the pectoral fin that is serrated, but the second rakers on the second and third arches. THEISEN upper ray, as a very small first dorsal ray is present (1965) gave a thorough description of the cranial partly hidden under the skin at the basis of the morphology. serrated ray). The type species of the genus Ipnops is I. muvvayi Figs. 1 and 2 show some of the meristic characters Giinther, 1878. GUNTNER'Stype material included of the Ipnops specimens examined herein (51 speci- four specimens, three from two Atlantic stations mens). The number of gill rakers of the specimens and one from off the Philippines. GUNTHERdid not in Fig. 1 is an average of the rakers from the left select a type-specimen or indicate the type locality. and right arches. As indicated by the different However, GREY(1956) designated "Challenger" St. signatures the material can be split into three 133 (35"S, 20°W) as the type locality. Furthermore, groups. Two specimens considered as possible the specimen on which GUNTHERbased his discrip- hybrids are kept separate (7). tion and illustration was also caught at St. 133. It 1. The group signified by (s), representing I. is thus appropriate to choose this specimen as the agassizi Garman, 1899, includes the individuals lectotype (Brit. Mus. Cat. No. 8, 260, 202). GUN- referred to I. agassizi and I. pristibrachium, the John THER'S type material evidently belongs to two differ- Murray Expedition material originally referred to I. murrayi by NORMAN(1939), and parts of the 1. The specimen mentioned by GILCHRIST(1908) is lost "Galathea" material (Table 4, p. 57). (PENRITHin litt.), and three of the "Galathea" specimens 2. The intermediate group signified by (o),repre- were sectioned for anatomical studies and are thus un- senting I. murvayi Giinther, 1878, comprises the fitted for the present treatment. 2. An unknown number was caught at "Oregon" St. 2821 lectotype and two more specimens of I. muvrayi (MEAD1966). from the "Challenger" Expedition, the specimens Fig. 1. Variation of the number of "Gill rakers 5E on the anterior arch", "Lateral line scales", and "Vertebrae" in the genus Ipnops. Symbols: 5i I. mumayi Giinther, 1878 (O),I. agassizi Garman, 1899 (w), I. meadi n.sp. (8),Ipnops 56 specimens (8). I - 51 52 53 54 55 56 57 58 59 60 61 Number of vertebrae from the "Blake", and from the "Oregon" Expe- as subspecies with different geographical distribu- dition, i. e. all the Atlantic Ipnops material (Table 3, tions. (See also p. 61). columns 1-6). 3. The third group signified by (e), representing a Biology: new species, I. meadi, consists of the major part of Bottom fishes found at abyssal depths in a tem- the "Galathea" material, the specimen caught by perature interval of 1,9"-3,g°C. I. murrayi and the "Challenger" in the Celebes Sea, and the agassizi were caught at depths from 1392-3475 m "Albatross" specimen from off Peru (Table 5, p. 60). and meadi from 3310-4970 m. No essential differences are found among the Otoliths are found in muvvayi and agassizi, while morphometric characters of the Ipnops species. One they are absent in meadi, a feature which might character "Length of head" shows an allometric have biological significance. The presence or absence growth (Fig. 3). of otoliths has nothing to do with the method or Among the Ipnops species, murrayi and agassizi period of preservation. The mouth is large, provided are the most closely related. This is evident from with small pointed teeth, and the gill rakers are almost all the meristic characters and also from numerous and well-developed, on the three anterior the presence of otoliths and of the very small upper arches. The Ipnops species, equipped with this pectoral ray. Furthermore, these two species have effective sieve, apparently feed on small animals as the same bathymetrical distribution (Table 1).