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Author: (Gilbert, 1892)

Diagnostic Features:
Body relatively slender, trunk slightly tapering toward head. Snout moderately long, rather broad, and bell-shaped, preoral snout about 7% of total length; gill slits moderately large, the longest about equal to eye length; gill septa more or less incised, not pleated and without projecting medial lobes; eyes rather small in adults, about 2.5% of total length; nostrils broad, their width about equal to internarial space; incurrent and excurrent apertures moderately large and transversely oval, anterior nasal flaps fairly long; mouth moderately long, not greatly enlarged, and broadly arched, with dental bands slightly expanded and with lower ones falling just behind uppers; mouth and labial furrows under eyes; labial folds not enlarged, with lowers diagonal to body axis; mouth and teeth not greatly enlarged in males. Interdorsal space equal or slightly greater than first dorsal base,slightly less than preorbital snout; first dorsal fin about as large as second, bases about equally long; origin of first dorsal slightly anterior to pelvic midbases; second dorsal insertion in front of anal insertion; pectoral fins rather small, anterior margins about 12% of total length; inner margins long, nearly length of pectoral bases; interspace between pectoral and pelvic bases moderately long, about equal to prebranchial length and about 16% of total length in adults; pelvic fins fairly high and broadly rounded; anal fin fairly short, high, and angular, slightly more than 2.5 times as long as high, its base slightly greater than prespiracular space and 13% of total length in adults; caudal fin rather broad, without a crest of enlarged denticles on dorsal margin. Lateral trunk denticles with crowns somewhat elevated, body surface with a feltlike or fuzzy texture. Colour dark brown, with conspicuous light posterior margins on fins. Adults moderately large, 42 to 69 cm.

Geographical Distribution:
Eastern Pacific: British Columbia, Canada, to northern Baja California, Mexico, probably south to Panama, Ecuador and Peru.

Habitat and Biology:
A little-known, common deepwater bottom shark from the outer continental shelf and upper slope from 33 to 950 m depth, also well off the bottom.

Oviparous, laying a single egg per oviduct at a time; egg cases about 5 cm long and 2.5 wide, with long tendrils. Incubation period of eggs possibly about 1 year. In Canadian waters, females carry egg cases from February to August.

Eats primarily small true shrimps, but also euphausiid shrimps, squids, and small fishes.

Attempts have been made to keep this small harmless shark in captivity, without notable success (up to two weeks).

Size:
Maximum 68 cm, males adolescent at about 50 cm, adults males 49 to 57 cm, adult females 42 to 49+ cm, size of young at hatching about 7 cm.

Interest to Fisheries:
Commonly taken in deeper bottom trawl hauls, but not utilized at present.

Remarks:
Until relatively recently all Apristurus caught north of Baja California in the eastern North Pacific were referred to this species. Apart from A. kampae and a possibly new species of heavy-bodied, kampae-like Apristurus from off California, the rather large number of specimens of Apristurus brunneus in the collections of the California Academy of Sciences and elsewhere in the western North Pacific may represent more than one species of brunneus-like catsharks. The writer has examined the holotype of A. brunneus and compared it to available 'brunneus' material, and suspects than an additional species, with smaller, flat, smooth denticles, a much longer, lower anal and caudal fin, lower pelvic fins, smaller gills, narrower snout, larger pectoral fins, and less expanded dental bands is present in this material. Whether this is identical to A. nasutus or some other species, or is new, remains to be seen.

Type material:
Holotype: U.S. National Museum of Natural History, USNM, 51708,500 mm, gravid female. Type Locality: 32°49'N, 117°29'W, 556 m depth off La Jolla, California.

Brown catshark (Apristurus brunneus)