Austrolebias pelotapes can be diagnosed from all members of the A. adloffi group by having the urogenital papilla base attached by a thin membrane to the anterior margin of the anal fin in males (vs. urogenital papilla free). It differs from all other species of theA. adloffi group with the exception of A. pongondo, by having a transverse row of small spots on the middle portion of the dorsal fin in males (vs. transverse row absent), unpaired fins with a single row of light blue spots on their basal portion in males, and with distinctive dark grey zone on the posterior portion of the dorsal and anal fins (vs. multiple rows of blue dots and distinctive dark grey zone absent in A. charrua and A. minuano), and caudal peduncle mostly dark brownish grey or dark grey to black, with narrow vertical light blue zones in males (vs. alternating dark grey and light blue bars, dark grey bars slightly wider, equal or narrower than light blue bars, in A. adloffi, A. nachtigalli, A. nigrofasciatus, A. reicherti). It is distinguished from A. pongondo by having 14-19 neuromasts in the supraorbital series (vs. 20-21) and 22-23 neuromasts around orbit (vs. 24-27), and also color pattern in live males with grey bars on the flank barely contrasting with the light blue color ground (vs. dark grey to black bars in deep contrast to light blue interspace in A. pongondo) and lack of a row of blue dots on the basal portion of the caudal fin (vs. presence) (Ref. 118050).