Gymnocorymbus flaviolimai is distinguished from all congeners, except G. ternetzi, by its relatively smaller dentary and premaxillary teeth, with approximately one half the size of the length of those teeth. It can be separated from G. ternetzi by having premaxillary teeth with five cusps (vs. teeth with three cusps). It further differs from G. bondi and G. thayeri by the strongly convex distal margin of the anal fin (vs. straight in G. bondior slightly convex in G. thayeri), and by having i,6 pelvic-fin rays (vs. i,7) (Ref. 101636).

Description: Dorsal-fin rays ii, 9; anal-fin rays iv,36-41; pectoral-fin rays i,10,i or i,11,i; pelvic-fin rays i,6; scale rows between lateral line and pelvic-fin origin 7, 8 or 9 (Ref. 101636).