This species is distinguished from all its congeners by having a black, oblique stripe that largely parallels and covers the second and third anal-fin rays, extending from the origin of the second branched ray to the distal end of the third branched anal-fin ray (vs. anal fin hyaline, with uniformly distributed chromatophores, or margin blackish in all other congeners); further distinguished from other congeners by the absence of a conspicuous black midlateral stripe on the body and inner premaxillary teeth with up to seven cusps; differs from Hemigrammus unilineatus (Gill 1858), a non-congener but similar species, by having A 20-23 (vs. 24-25), maxilla with 2 or 3 tetra to heptacuspidad maxillary teeth (vs. 3-7 tricuspidad maxillary teeth) and caudal fin without scales (vs. caudal-fin lobes scaled) (Ref. 118106).