Distinguished from its congeners by the following characters: caudal fin deeply forked; outer, unbranched principal rays of upper and lower lobes longest in each lobe and about equal in length; posterior fontanelle elongate, forming conspicuous groove on supraoccipital bone, skin pigmented black in groove (vs. congeners which are without elongate posterior fontanelle, supraoccipital groove, or black pigment); unique in having combination of elongate body and broad-shaped head (vs. congeners with either elongate body and head, or stout body with broad head) (Ref, 57983).