Author: Teng, 1962
Hexanchus nakamurai Teng, 1962
Status in World Register of Marine Species:
Accepted name: Hexanchus nakamurai Teng, 1962 (updated 2009-06-25)
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 and 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 and Waller, employed by most recent authors, should be retained.
Eggs, larvae and young stages. Springer and Waller, 1969: 1671 Bigelow and Schroeder, 1948, fig. 9A (cf. Springer and Waller, loc. cit.).