Diagnosed from all other congeners of the subgenus Melanorivulus in possessing 2+1 mandibular neuromasts. Differs from all species of Melanorivulus, except Rivulus violaceus by its caudal peduncle in both sexes with dark purplish gray spots and humeral region in males with a bright greenish blue blotch. Can be separated from Rivulus violaceus by having fewer dorsal-fin rays 8-9 (vs. 10-11) and fewer anal-fin rays 11-13 (vs. 14-15). Additional characters helpful in the identification of this species include: scales in the longitudinal series 30-31; flank with close red dots, arranged in chevron-like series with the vertex on the mid-lateral line; and caudal fin in males with red bars (Ref. 76975).