Author: Rafinesque, 1810
Diagnostic Features:
Anterior nasal flaps short, not expanded into barbels; snout broadly conical, rounded, and short, length much less than distance from mouth to pectoral origins and about 1/4 of head length; gill openings moderately broad and about equally wide; lips very thick, fringed or pleated, not suctorial; teeth very different in upper and lower jaws, uppers small, with narrow, hooked, needle-shaped cusps and no cusplets, lowers very large, bladelike, interlocked, with broad, erect, triangular cusps, small distal blades, and serrated edges; tooth rows 16 to 21/17 to 20. Both dorsal fins without spines; first dorsal origin somewhat behind free rear tips of pectoral fins, first dorsal insertion well anterior to pelvic origins, eloser to pectoral bases than pelvics; second dorsal origin about over middle of pelvic bases; second dorsal fin only slightly larger than first, its base less than 1.5 times first dorsal base; pectoral fins with short, broadly rounded free rear tips, not broadly lobate or acute and elongated; caudal fin asymmetrical, not paddleshaped, upper lobe long, lower lobe very short or virtually absent, subterminal notch well-developed. No precaudal pits or lateral keels on caudal peduncle. Dermal denticles with low flat, ridged, unicuspid crowns, not pedicellate. Cloaca without a luminous gland. Colour greyish to black or blackish brown, sometimes violet with black spots.
Remarks:
A number of writers have used the genus Scymnorhinus for Squalus licha Bonnaterre, 1788 on the grounds that the synonymy of Dalatias sparophagus with S. licha is invalid because D. sparophagus is a species dubium and indeterminate. I follow common recent usage (Bigelow and Schroeder, 1948, 1957; Garrick, 1960a; Bass, d'Aubrey and Kistnasamy, 1976) in retaining Dalatias, at least until the International Commission on Zoological Nomenclature rules on the problem.