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Characteristics, distribution and ecology
Taxonomische classification
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Author: (Gilchrist, 1922)

Field Marks:
A catshark with an extremely broad head, no labial furrows, nostrils separate from each other and mouth, and without barbels or nasoral grooves, dorsolateral gill slits, second dorsal fin usually somewhat larger than first, first dorsal with origin about over rear end of pelvic bases, second dorsal base partly behind anal base, dorsal surface appearing dark brown with reticular pattern of light lines, underside ofhead with tiny dark dots, no conspicuous white spot over pectoral insertion in adults.

Diagnostic Features:
Second dorsal fin usually larger than first; anal base over 312 times its height, usually longer than interdorsal space (except in very young individuals).

Denticles on back and top of head not of uniform size, enlarged spiky denticles scattered among more numerous small denticles. Colour pattern variable but usually with large, irregular, sometimes light-centred, very closelyspaced brown spots on back giving back dark-brown cast with a reticular patternof light lines; no white spot over pectoral insertion in adults, although young have a line of white spots on sides; dorsal fins of adults generally spotted but without dark lines or double-Vs. A larger species, adult males 50cm and females 38 + cm.

Geographical Distribution:
Eastern South Atlantic and western Indian Ocean: South Africa, Mozambique, Tanzania, Somalia ?

Habitat and Biology:
A common, deepish-water temperate and tropical catshark with a broad depth range from the outer continental shelf and upper slope on or near bottom at depths of 160 to 740 m. The species may occur in shallower water (160 to 460 m) at the Cape of Good Hope in the temperate region than off tropicalsubtropical Tanzania and southern Mozambique (240 to 740 m).

Oviparous, one egg per oviduct laid at a time. Egg-cases about 3.5 by 1.5 cm. Hatchlings not recorded, but a 13 cm immature illustrated by Bass, D'Aubrey and Kistnasamy (1975a, fig. 15) is remarkable in being quite divergent in morphology from adults and subadults, with an all-dark body with white spots and black bars on fins, slender body, minute fins, and an extremely long tail.

Feeds heavily on cephalopods, with lesser amounts of bony fishes and crustaceans.

Maximum 61 cm, males maturing at 50 to 54 cm and reaching 61 cm, females maturing at 38 to 39 cm and reaching 41 cm. As in H. punctatus, males are substantially larger than females. Size at hatching unknown, below 13 cm.

Interest to Fisheries:
None at present, commonly taken by commercial bottom trawlers.

Bass, D'Aubrey and Kistnasamy (1975a) note that the holotype of Scyliorhinus (Halaelurus) melanostigma and three of its four paratypes (all from off Zanzibar) are conspecific with H. regani (the fourth paratype is H. punctatus or a closely related species). These writers note considerable colour differences between H. regani specimens from the southwestern Cape Province of South Africa and those from Northern Natal and southern Mozambique. Without taking the problem further, Bass, D'Aubrey and Kistnasamy suggest that the wideranging H. regani might represent a group of closely related species (presumably with H. melanostigma one of these, as contrasted with the Cape H. regani), but with insufficient coverage of material these writers quite justifiably include all of the regani-like catsharks in one species.

Type material:
Probable syntypes: J.L.B. Smith Institute of Ichthyology, Grahamstown, South Africa, RUSI 952, two females, 215 and 269 mm. Type Locality: "Cape Seas" (Cape of Good Hope, South Africa), from 174 to 320 m depth.

Izak catshark (Holohalaelurus regani)