Bighead spurdog (Squalus bucephalus)

Biology

This large, broad-headed species of the 'megalops-cubensis group' is distinguished by the following set of characters: head width at mouth 12.1-13.5% TL; mouth width 2.2-2.7 times its horizontal prenarial length; direct pre-second dorsal length 3.9-4.0 times the pectoral-fin anterior margin, 2.7 times dorsal caudal margin; preoral length 2.7-3.1 times the horizontal prenarial length, 9.2-10.5% TL; strongly bifurcated anterior nasal flap; low and raked first dorsal fin; exposed bases of dorsal-fin spines are broad, 0.7-0.8% TL; both dorsal fins with short inner margins, first dorsal-fin height 1.4-1.5 times its inner margin length, second dorsal-fin height 0.8-1.0 times its inner margin length; pectoral-fin anterior margin 1.8-2.0 times its inner margin length; preventral caudal margin 1.8-2.2 times the inner margin of pelvic fin; dorsal fins with dark distal portion, posterior margin of free rear tip pale; caudal fin upper posterior margin broadly white, lower lobe with dark base and

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