This species is easily diagnosed from other species of Gephyrocharax, except G. melanocheir, by the absence or vestigial adipose fin (vs. presence of a well developed

adipose fin), the form of lateral branched pectoral-fin ray of males which has a highly developed branching pattern that distally forms a fan-shaped structure with minute branches (vs. less extensive branching pattern not distally forming a fan-shaped structure with such minute branches), and the distal portion of this pectoral-fin ray in males with minute bony hooks (vs. hooks absent) and a dark blotch or a few scattered dark brown chromatophores along its branches (vs. blotch or chromatophores absent). It differs from G. melanocheir by the following characters: intense black pigmentation at the base of the anterior five dorsal-fin rays absent (vs. present); 40-41 vertebrae (vs. 38-39); frontals contacting each other anterior to epiphyseal bar in adults (vs. the absence of contact); the posterior margin of the mesethmoid straight in its central portion (vs. strongly concave at this point); the pouch scale of mature males reaching caudal-fin ray 11 or the area between caudal-fin rays 11 and 12 (vs. reaching only to caudal fin ray 10 or the area between caudal-fin rays 9 and 10); 60-88 minute terminal branches of the lateral branched pectoral-fin ray of mature males (vs. 28-54); the longer midlateral black body stripe in males, reaching to the base of the caudal-fin rays (vs. reaching to the middle of the caudal peduncle); and the snout length 28.3-31.8% HL (vs. 22.1-28.0% HL) (Ref. 93810).