Author: Fowler, 1934
Field Marks:
Extremely broad-headed short-snouted catsharks without labial furrows, with long mouths and long, low fins, slender tails, very bold, bright, spotted dorsal colour patterns and scattered black dots on underside of head.
Diagnostic Features:
Body not tadpole-shaped, fairly stout and spindle-shaped, tapering considerably to caudal fin; body firm and thick skinned, with well-calcified dermal denticles; stomach not inflatable; tail moderately long, length from vent to lower caudal origin over 4/5 of snout-vent length. Head greatly depressed and very broad, narrowly pointed and somewhat wedge-shaped in lateral view; head short, less than 1/5 of total length in adults; snout rather short, less than 3/5 of mouth width, thin, and very flattened, pointed in lateral view; snout somewhat expanded laterally, rounded-parabolic and slightly bell-shaped in dorsoventral view; ampullal pores not greatly enlarged on snout; nostrils fairly large, with incurrent and excurrent apertures only partly open to exterior; anterior nasal flaps broadly triangular, without barbels, well separate from each other but nearly or quite reaching level of mouth; internarial space about 1 to 1.3 times the nostril width; no nasoral grooves; eyes dorsolateral on head, very broad subocular ridges present below eyes. Mouth semiangular, very long, with lower symphysis well behind upper so that upper teeth are exposed in ventral view; labial furrows absent from both jaws; branchial region not enlarged, distance from spiracles to fifth gill slits 2/5 of head length; gill slits dorsolateral on head. Two dorsal fins present, the second slightly larger than first; origin of first dorsal varying from about over the pelvic midbases to slightly in front of their insertions; origin of second dorsal about over the last third of the anal base; pectoral fins moderately large, their width subequal or somewhat Tess than mouth width; inner margins of pelvic fins not fused over claspers in adult males; claspers moderately long, slender and distally pointed, extending about half of their lengths behind the pelvic fin tips; anal fin moderately large and definitely elongated, about as large as pelvic fins or larger, and larger than the dorsals; base length 1.5 to 2 times second dorsal base; origin of anal well behind pelvic bases, and insertion separated from lower caudal origin by a broad space subequal to the anal base; caudal fin moderately elongated, between 1/4 to 1/5 of total length in adults. No crest of denticles on the caudal margins; supraorbital crests absent from cranium. Colour light with a conspicuous colour pattern of dark spots and blotches on dorsal surface, unique small black dots on underside of head.
Remarks:
The writer follows Bigelow and Schroeder (1948), Bass, D'Aubrey and Kistnasamy (1975a), and Springer (1979) in recognizing this genus, though the differences between it and the closely related Halaelurus are fairly small. An alternate arrangement as originally proposed by Fowler (1934) is ranking this taxon as a subgenus of Halaelurus.