Marine Species Identification Portal : Blacktip tope

Author: (Miyosi, 1939)

Field Marks:
A slender, moderately long-nosed houndshark with vestigial anterior nasal flaps, large horizontally oval eyes with internal nictitating lower eyelids, subocular ridges obsolete, an angular mouth, moderately long upper labial furrows that fall short of lower symphysis, bladelike compressed teeth with oblique cusps and distal cusplets in both jaws, second dorsal fin somewhat smaller than first but larger than anal fin, and a relatively short terminal caudal lobe much less than half the dorsal caudal margin.

Diagnostic Features:
Snout moderately long and parabolic in dorsoventral view, preoral length about equal to mouth width; eyes horizontally oval and lateral, subocular ridges obsolete; anterior nasal flaps vestigial, formed as small, low, angular points, well separated from each other and mouth; no nasoral grooves; internarial width over 2.5 times nostril width; mouth angular and long; labial furrows moderately long, uppers ending well behind level of upper symphysis; teeth bladelike compressed, and cuspidate, similar in upper and lower jaws, anteroposteriors with oblique cusps and cusplets; medial teeth well differentiated from anteroposteriors. First dorsal fin moderately large, its base half length of dorsal caudal margin or less; its origin over or slightly behind pectoral free rear tips, its midbase somewhat closer to pectoral bases than pelvics; second dorsal considerably smaller than first, about 1/2 to 3/5 as high as first; anal fin considerably smaller than second dorsal; ventral caudal lobe strong in young and adults; terminal lobe of caudal fin moderately long and about 2.6 to 3 times in dorsal caudal margin.

Geographical Distribution:
Western Indian Ocean: South Africa (Natal), Tanzania (Zanzibar), Kenya, the "Gulf". Western North Pacific: Taiwan Island (Province of China), Japan.

Habitat and Biology:
A little-known, deepish water tropical and subtropical shark of the continental shelves found at 40 to 230 m depth near the bottom. Viviparous, with a yolk-sac placenta; number of young 10 or 11 to a litter. Gestation period estimated at 15 months with birth period in December in South African waters. Eats bony fishes.

Size:
Maximum about 127 cm, adult males 112 to 127 cm, adult females 114 to 122 cm; full-term fetuses about 33 to 35 cm long.

Interest to Fisheries:
A minor fisheries catch off Japan, probably taken in gillnets, line gear, and bottom trawls, and utilized for human consumption, but apparently uncommon and unimportant elsewhere.

Type material:
Holotype: "Preserved at Matuyama Girl's High School of Matuyama City, Ehime Prefecture" (Miyosi, 1939), 904 mm female. Type Locality: Hyuga Nada, off east coast of Miyazaki Prefecture, Japan.

Status in World Register of Marine Species

Accepted name: Hypogaleus hyugaensis (Miyosi, 1939)

Scientific synonyms and common names

Hypogaleus hyugaensis (Miyosi, 1939)

Eugaleus hyugaensis Miyosi, 1939, Bull.Biogeogr.Soc.Tokyo, 9(5):91, fig. 1.

Synonymy:
Galeorhinus (Hypogaleus) zanzibariensis Smith, 1957.

FAO Names:
Blacktip tope [English]
Requin-hâ élégant [French]
Cazón elegante [Spanish]
TRIAK Hypo 1 [FAO Code]

Blacktip tope (Hypogaleus hyugaensis)