Epetriodus freddyi Cohen and Nielsen, 1978

Ohashi, Shinpei & Endo, Hiromitsu, 2015, First Record of a Rare Cusk Eel, Epetriodus freddyi, from the Northern Hemisphere (Actinopterygii: Ophidiiformes: Ophidiidae), Species Diversity 20 (1), pp. 23-27 : 23-26

Epetriodus freddyi Cohen and Nielsen, 1978

[New Japanese name: Kurosode-itachiuo] ( Figs 1–4 , Table 1)

Epetriodus freddyi Cohen and Nielsen, 1978: 30 (original description, type locality: off Mozambique, southwestern Indian Ocean, 21°18′S, 36°18′E); Shcherbachev 1980: 143 (record and description, east of South Africa, western Indian Ocean, 32°30′S, 35°02′E); Nielsen and Cohen 1986: 345 (short description, western Indian Ocean); Williams et al. 1996: 148 (record and list, Western Australia, 24°30′S, 111°51′E– 27°07′S, 112°23′E); Nielsen 1999: 1980 (list, western Pacific Ocean); Nielsen and Cohen 1999: 64 (short description, off east Africa to New Caledonia); Hutchins 2001: 23 (list, Western Australia); Hoese et al. 2006: 559 (list, Indo-West Pacific); Fricke et al. 2011: 366 (list, New Caledonia).

Material examined. BSKU 86813 , female, 184 mm SL, Hyuga-nada basin off Kochi Prefecture, Japan, Pacific Ocean (32°24.447′N, 132°16.027′E– 32°25.188′N, 132°17.909′E), 1,501–1,516 m depth, 3 m beam trawl, R / V Tansei-maru (KT-99-18, BT-4), 16 December 1999, collected by H . Endo and S . Nagatomo.

Diagnosis. Dorsal-fin rays 93–98; anal-fin rays 72– 78; pectoral-fin rays 24–29, fully joined by membranes; pelvic-fin rays 2, filamentous; caudal-fin rays 8; vertebrae 52–54 (12–13+39–42); long gill rakers on first arch 21–23; body relatively short, eye small (diameter about half snout length), needle-like teeth on both jaws, vomer, and palatines; two median tooth patches on basibranchial; opercular spine short and sharp; modified fourth and fifth centra with lower projection.

Description. Selected counts and measurements provided in Table 1. Body short and compressed, depth at anus about 5.8 times in SL. Head relatively large, its length about half preanal length. Snout blunt. Two pairs of nostrils between tip of snout and eye; anterior nostril nearly at tip of snout, small with fleshy rim, its diameter about one third of eye diameter; posterior nostril slightly larger than anterior one, situated immediately anterior to eye. Eye small, its diameter about half snout length. Mouth large, subterminal. Posterior end of maxilla extending well beyond posterior margin of eye. Supramaxilla posterodorsal to maxilla, elliptical. Upper jaw slightly projecting anteriorly beyond lower jaw. Both jaws with several rows of needle-like teeth ( Fig. 2 ); teeth larger anteriorly on premaxilla, and posteriorly on dentary. Teeth on vomer and palatines needle-like, well developed, uniformly spread on former, but rudimentary on posterior part of latter. Two median basibranchial tooth patches covered with small teeth, not contiguous. Anterior tooth patch relatively slender; posterior patch elliptical, its length about half that of anterior patch. Paired basibranchial tooth patches absent. Preopercle soft; its hind margin without spines. Opercle small, falcate with short, sharp spine; its posterior tip not reaching posterior margin of subopercle. Gill opening wide; its upper end above top of pectoral-fin base. Anterior gill arch with both long and rudimentary rakers, former comb-like on ceratobranchial and epibranchial, latter knob-like on hypobranchial and epibranchial. Pseudobranchial consisting of two short filaments. Branchiostegal rays 8. Head pores obvious; 5 in suborbital, 1 in supratemporal, and 7 in preoperculo-mandibular regions. Head and body with small cycloid scales, excluding isthmus, posterior portion of gill membrane, axilla of pectoral fin, and bases of dorsal and anal fins. Lateral line running near dorsal-fin base from upper angle of gill opening, obscure on posterior portion of body, having narrow and naked tube with small pores ventrally. Pectoral fin broad and rounded; its branched fin rays fully joined by membranes. Dorsal- and anal-fin bases long, continuous with caudal fin posteriorly; their rays unbranched. Dorsal-fin origin above pectoralfin base. Anal-fin origin below 25th dorsal-fin ray. Pelvic fin with two filamentous rays separated near tip; longer, inner ray reaching posteriorly beyond midpoint between pelvic-fin base and anal-fin origin. Pelvic-fin origin below hind margin of preopercle. Caudal fin slender with eight rays. Anus just anterior to anal-fin origin. Fourth and fifth abdominal vertebrae modified; posteroventral portion of fourth and anteroventral portion of fifth projecting downward ( Fig. 3 ). Mature ovaries slightly protruding.

Color when fresh ( Fig. 1A ). Ground color of body and head pale brown. Head relatively darker than body. Fins dark brown except near base of pectoral. Posterior portion of opercular region and abdomen dark blue.

Color in alcohol ( Fig. 1B ). Body, jaws, and cheek pale. Snout, area around eye, oral cavity, opercular region, pectoral-fin base, and margins of dorsal and anal fins dusky brown. Abdomen and pectoral fin, excluding its base, dark. Pelvic fin slightly dark.

Distribution. Known from Mozambique, South Africa, and Western Australia in the Indian Ocean, and Wallis and Futuna, and Japan in the western Pacific Ocean, at depths of 714–1,750 m ( Cohen and Nielsen 1978; Shcherbachev 1980; Williams et al. 1996; Nielsen and Cohen 1999; J. G. Nielsen pers. comm.; this study) ( Fig. 4 ).

Remarks. The present specimen identified as a species of Epetriodus is clearly distinguished from other genera by its unique possession of numerous needle-like teeth on both jaws as well as the vomer and palatines ( Fig. 2 ), and the following combination of characters: eye small, its diameter about half snout length; two median basibranchial tooth patches; 21 long gill rakers on first arch; pectoral-fin rays fully joined by membranes; and two pelvic-fin rays ( Nielsen and Cohen 1999). The morphology of the specimen also agrees well with the original description of its only known species E. freddyi by Cohen and Nielsen (1978) and with the additional specimens examined in this study ( Table 1), including the obvious head pores and modified fourth and fifth centra ( Fig. 3 ). We regard the slight difference in the number of total vertebrae (52 vs 53–54) as intraspecific variation.

Although Fricke et al. (2011) gave “ 100–1,750 m ” as the habitat depth of E. freddyi , the reference for this range is Nielsen and Cohen (1999), which stated it as “ 1,000 – 1,750 m ”. We therefore consider the depth range of Fricke et al. (2011) to be erroneous. Nielsen and Cohen (1999) noted the distribution of the species as “from off East Africa to New Caledonia ” without references . The known distribution at that time should have been “from off East Africa to Wallis and Futuna ”, because the western Pacific specimens examined were actually from Wallis and Futuna, a French territory northwest of Fiji (12°34′S, 178°15′W) (J. G. Nielsen pers. comm.) .

Because previous records of E. freddyi were restricted to the Indian Ocean and western Pacific Ocean in the Southern Hemisphere, the present specimen represents the first record of the genus and species from the Northern Hemisphere. New standard Japanese names, “ Kurosode-itachiuozoku ” and “ Kurosode-itachiuo ” for the genus and species respectively, are proposed based on the specimen BSKU 86813. These names refer to the coloration of the pectoral fin.

Comparative materials. Epetriodus freddyi , five specimens: MNHN 1997-0719, 115 mm SL, Wallis and Futuna, northwest of Fiji (12°34.48′S, 178°10.12′W), 1,280 –1,300 m depth, N/O Alis (Musorstom 7, st. cp622), 28 May 1992; MNHN 1997-0720, 133 mm SL, Wallis and Futuna, northwest of Fiji (12°34.12′S, 178°15.00′W), 1,280 –1,300 m depth, N/O Alis (Musorstom 7, st. cp623), 28 May 1992; CSIRO H 2562-02, 191 mm SL, west of Quobba Point, Western Australia (24°30.2′S, 111°50.9′E– 24°28.1′S, 111°51.4′E), 892–905 m depth, FRV Southern Surveyor (st. SS0191/24), 28 January 1991, coll. by P. Last ; CSIRO H 2571-03 , 198 mm SL, west of Dirk Hartog Island , Western Australia (26°02.1′S, 111°39.3′E– 26°01.3′S, 111°37.9′E), 1,000– 1,005 m depth, FRV Southern Surveyor (st. SS0191/34), 29 January 1991, coll . by P. Last ; CSIRO H 2572–08 , 198 mm SL, west of Dirk Hartog Island , Western Australia (26°05.3′S, 111°46.7′E– 26°04.4′S, 111°47.1′E), 874–882 m depth, FRV Southern Surveyor (st. SS0191/35), 30 January 1991, coll . by P. Last.

Figures

Fig. 1. Epetriodus freddyi, BSKU 86813, 184mm SL, Hyuga-nada basin, southwest of Kochi, southern Japan. (A) Specimen just after captured; (B) specimen preserved in 70% ethanol.

Fig. 2. Needle-like teeth on (A) upper and (B) lower jaws of Epetriodus freddyi, BSKU 86813.

Fig. 3. Radiograph showing abdominal vertebrae of Epetriodus freddyi, BSKU 86813, 184mm SL.

Fig. 4. Records of Epetriodus freddyi, marked by closed and open circles representing present and previous records, respectively. Numbers indicate multiple neighboring stations. “H” means locality of holotype.