Cynolebias gorutuba is similar to other members of the Cynolebias zeta-clade or CZC (C. altus, C. attenuatus, C. gibbus, C. leptocephalus, C. parietalis, C. perforatus, C. oticus), and differs from all other congeners, by having contact organs distributed on the inner surface of entire pectoral fin of males (vs. restricted to the dorsal portion of the fin), trunk scales extending over base of dorsal fin (vs. not extending), scales extending over one third or more of base of caudal fin (vs. about one fourth), and gill-rakers of first branchial arch bowed and with numerous denticles on its surface (vs. straight to slightly curved, usually without denticles, or one or two when present). It can be diagnosed from all other congeners of CZC by having small round dark grey spots on dorsolateral portion of the trunk in females (vs. absent) and by the second proximal radial of dorsal fin between neural spines of 16th and 18th vertebrae in males (vs. between neural spines of 14th and 16th vertebrae). It differs also from all members of the Cynolebias zeta-clade, except C. oticus, by having 75-87 preopercular neuromasts (vs. 53-72). It can be differentiated from C. oticus by having convex ante¬rior lateral profile of the body (vs. no con¬cavity on the head), otic and post-otic neuromast series separated (vs. united), 37-38 vertebrae (vs. 35-36), and lack of bars on the flank in males above 75 mm SL (vs. presence), and from C. parietalis and C. perforatus by fewer rays in caudal fin (30-31 vs. 33-35) (Ref. 118117).