Author: Teng, 1962

Hexanchus nakamurai Teng, 1962

Diagnosis: similar to H. griseus but head less broad, snout longer and pointed; also, anterior cusp of teeth much larger, especially in upper jaw, upper front 4 rows of teeth in advance of line formed by lateral teeth, lower lateral teeth in 5 rows. Gill-slits 6. Spineless dorsal fin more advanced, mostly before anal fin base; pectoral fins with somewhat concave posterior margin; lower caudal lobe distinct. Colour: plain grey, slightly darker dorsally. Size: to about 1.8 m TL.

Habitat: probably mesopelagic to benthic in deeper waters (recorded from 90 to 350 m), possibly with excursions to surface or shallows; in warmer seas than H. griseus. Food: only fish recorded. Reproduction: ovoviviparous, litters of up to 26 embryos known; about 40-45 cm at birth.

Distribution: occurs in warmer waters of Clofnam area, where possibly confused with H. griseus (which it probably replaces). Elsewhere, Florida, Gulf of Mexico, Caribbean area, southern Atlantic, south-western Indian Ocean (Natal to Kenia) and Taiwan.

Note: the availability of Teng's paper for nomenclatural purposes has been considered by recent authors (Compagno, 1984; Taniuchi & Tachikawa, 1991; Tortonese, 1985; also Boeseman 1984:[1427]), without reaching unanimity. If further evidence proves the name nakamura to be invalid, the name H. vitulus Springer & Waller, employed by most recent authors, should be retained.

Eggs, larvae and young stages. Springer & Waller, 1969: 1671 Bigelow & Schroeder, 1948, fig. 9A (cf. Springer & Waller, loc. cit.).

Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
Superclass Gnathostomata
Class Chondrichthyes
Superorder Pleurotremata
Family Hexanchidae
Genus Hexanchus
Species Hexanchus nakamurai

Status in World Register of Marine Species

Accepted name: Hexanchus nakamurai Teng, 1962

Scientific synonyms and common names

Hexanchus nakamurai Teng, 1962

Synonyms:

Hexanchus vitulus Springer & Waller, 1969, Bull. mar. Sci. Guy Caribb., 19 (1): 159-167, fig. 1-4 (near Bimini, Bahamas). Holotype: USNM no. 200674; paratype, USNM no 200675 (same locality).

Common names:

Bigeyed six-gill shark [En]
Requin vache [Fr]

Bigelow, H. B.; Schroeder, W. C. 1948b. Sharks. In: Fishes of the western north Atlantic. Mem. Sears Found. Mar. Res., New Haven, 1(1): 59-576, fig. 6-106.

Springer, S.; Waller, R. A. 1969. Hexanchus vitulus, a new sixgill shark from the Bahamas. Bull. mar. Sci. Guy Caribb., 19 (1) :159-174, fig. 1-7.

Taniuchi, T. & H. Tachikawa, 1991. Hexanchus nakamurai, a Senior Synonym of H. vitulus (Elasmobranchii), with Notes on its occurrence in Japan. Jap. Journ. Ichth., 38 (1): 57-60, 1 fig.

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