Scymnodon obscurus

Author: (Vaillant, 1888)

Field Marks:
Black coloration, small dorsal fin spines, no anal fin, moderately long snout, small lanceolate teeth without cusplets in upper jaw and large high, knife-cusped cutting teeth in lower jaw, mouth moderately wide and nearly transverse, caudal fin with strong subterminal notch and short lower lobe.

Diagnostic Features:
Head rather low and flat; snout rather narrow and long, preoral length greater than mouth width and almost equal to distance from lower symphysis to first gill slits; mouth fairly narrow, short and transverse; postoral grooves very long, much longer than upper labial furrows; gill slits rather short, longest less than half eye length. Pectoral fins narrow and leaf-shaped; apices of pectoral fins falling well in front of first dorsal spine; pelvic fins small, about equal to second dorsal fin; caudal fin with a strong subterminal notch and a short lower lobe. Lateral trunk denticles with cross-ridges on crowns. Caudal peduncle long, distance from second dorsal base to upper caudal origin about equal to second dorsal base.

Geographical Distribution:
Western Atlantic: Northern Gulf of Mexico; Surinam; southern Brazil. Eastern North Atlantic: Iceland and Faeroe Ridge to Madeira, Morocco, Cape Verde Islands, and Senegal. Western Indian Ocean: South Africa.

Habitat and Biology:
A little-known deepwater shark of the Atlantic and possibly Indian Ocean continental slopes, usually found on or near the bottom at depths of 550 to 1450 m; also epipelagic and oceanic off Brazil at depths between 0 and 580 m in water 2000 m deep. Probably ovoviviparous and a predator on bottom fishes and invertebrates, but its smaller teeth and mouth, and weaker jaws suggest that it is a predator less capable of killing large prey than its congener S. ringens.

Size:
Maximum total length about 59 cm; an adult male 51 cm, and an adult female 59 cm long.

Interest to Fisheries:
Reported as being caught in bottom trawls, with line gear, and with fixed bottom nets in the eastern Atlantic, and utilized dried salted for human consumption and for fishmeal.

Remarks:
As described by Krefft (1980) this species is very close to S. squamulosus and may be a junior synonym of that species.

Type material:
Holotype: Museum National d'Histoire Naturelle, Paris, MNHN-84-388, 590 mm female. Type Locality: "Cotes du Soudan", 1400 to 1435 m depth.

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