Genus Scoliodon

Author: Müller and Henle, 1838

Diagnostic Features:
Body moderately stout. Head broad, greatly depressed, and trowel-shaped; snout parabolic or bell-shaped in dorsoventral view, very long, with preoral length greater than internarial space and mouth width; eyes small, without posterior notches; spiracles absent; no papillose gillrakers on internal gill openings; nostrils small, internarial space about 4 to 6 times nostril width; anterior nasal flaps very short, narrowly triangular, and not tubular; labial furrows very short to rudimentary, with uppers shorter than lowers and falling far behind eyes; teeth similar in upper and lower jaws, anteroposteriors with slender oblique cusps and distal blades but no cusplets or serrations; cusps of lower teeth not prominently protruding when mouth is closed; 25 to 33/24 to 34 rows of teeth. Interdorsal ridge absent or rudimentary; no dermal keels present on caudal peduncle; upper precaudal pit transverse and crescentic. First dorsal origin over or behind pectoral rear tips, its midbase much closer to pelvic bases than to pectorals and its free rear tip about over pelvic midbases; second dorsal fin much smaller than first, its height 1/3 of first dorsal height or less, its origin behind anal midbase; pectoral fins very broad and triangular, not falcate, pectoral length from origin to free rear tip about equal to pectoral anterior margin; pectoral origins under interspace between fourth and fifth gill slits; anal fin much larger than second dorsal, with short preanal ridges and a straight or slightly concave posterior margin. Colour light grey, yellowish or brownish grey above, without a colour pattern.

Remarks:
The arrangement of this genus follows Springer (1964). See Compagno (1979) for a comprehensive account of the classification, nomenclature and relationships of the genus. Scoliodon is apparently the sister group of the hammerhead family Sphyrnidae, but is retained in the Carcharhinidae because it lacks all of the more extreme derived character states of hammerheads.

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