This is a sexually dimorphic species, with males possessing greatly elongate first spine of first dorsal fin, reaching eighth element of second dorsal fin when appressed; when preserved first dorsal fin brown or black with white distal edge, no spots; margin of first dorsal fin concave in males while concave to straight in females; second dorsal fin with two black bands, broader one located inframarginally and the other located medially, black spots basally on membrane between dorsal fin elements; pelvic fin with prominent frenum and inner rays fused for more than half of length. D1 modally IX; D2 modally I,12; A modally I,13; caudal fin rays modally 15 segmented rays, with first and last two rays unbranched; 62-67 lateral scale rows; 18-24 predorsal scales (Ref. 83659).