Author: (Gilbert, 1892)
A deepwater soft-bodied, plain catshark with a short snout, first dorsal origin just behind pelvic origins, second dorsal about as large as first, crest of enlarged denticles on dorsal caudal margin.
Snout broadly rounded; nasal flaps broad and triangular; gill septa not excavated and concave posteriorly. First dorsal fin about as large as second; first dorsal origin just behind pelvic origins; first dorsal insertion slightly in front of pelvic insertions; second dorsal smaller than anal fin; second dorsal origin nearly over anal origin; second dorsal insertion well in front of anal insertion; ventral edge of caudal peduncle and preventral caudal margin without a crest of enlarged denticles.
Eastern North Pacific: Central California, USA, to Gulf of California, Mexico.
Habitat and Biology:
A common but little-known deepwater shark of temperate to subtropical waters on the outer continental shelf and upper slope, often on or near the bottom but up to 490 m above, at depths of 91 to 1251 m. Has been seen from a deep-diving submersible on or near the bottom in the Santa Barbara Basin, an anoxic area with few if any other vertebrates commonly living in it. Apparently the enlarged gill region of this shark is an adaption to living in areas of low oxygen, as in the triakid Iago omanensis and presumably the bizarre, long-headed catshark Cephalurus cephalus.
Oviparous, egg-cases about 7 to 11 cm long by 3 to 4 cm wide, with unusual T-shaped lateral flanges. An egg collected in water at a temperature 6°C was kept in a refrigerator, but was only half developed when it died about a year later.
Probably eats a variety of small fish and invertebrate prey. Individuals were seen eating moribund lanternfish in the anoxic Santa Barbara Basin.
As in P. pilosus this species has a high concentration of squalene in its liver, which probably helps to adjust it to approximately neutral buoyancy.
Maximum 55cm; adult males 37 to 45 cm; adult females 47 to 55 cm.
Interest to Fisheries:
Regularly caught by bottom trawlers, but apparently not utilized at present.
Lectotype: U.S. National Museum of Natural History, USNM-46719, 550 mm female, presumably adult, one of 8 syntypes designated lectotype by Springer (1979:108). Type Locality: Off southern California, USA, 33°55.5'N, 128°28'W in 687 m depth.