The spined pygmy shark Squaliolus laticaudus is a very small dogfish (about 25cm) with a large eye (diameter 73-86% of interorbital width), upper margin nearly straight; upper lip without papillae (Ref. 31367, 6871). Color: dark with conspicuously light-margined fins (Ref. 247) . Edge of fins with bright border (Ref. 43998).

S. laticaudus is the type species of the genus which has the following distinctive features: fin spine on its first dorsal fin but not on its second dorsal fin; second dorsal fin long-based and low, about twice the length of first dorsal fin base; first dorsal-fin base closer to pectoral fins than to pelvic fins; and caudal fin nearly symmetrical, paddle-shaped, with subterminal notch present; low lateral keels on caudal peduncle . Body cigar-shaped; snout very long, bulbously conical but slightly pointed; mouth ventral; lips thin; teeth strongly different in both jaws, uppers small, narrow and erect cusps, lowers larger, blade-like and semi erect. Tooth rows 22-23/16-21. (Ref. 247, 6871).