This species differs from its congeners inhabiting the Río de La Plata and coastal basins of southern Brazil, except A. abilhoai, A. formoso, A. mullerae, A. multispinis and A. taunayi by possessing a maxillary barbel shorter and not free from lower lip (vs. longer and free from lower lip); from A. abilhoai by having the width of mandibulary teeth row 15.8-19.3% of HL (vs. 13.4-15.5%) and 38.4-53.6% of interorbital width (vs. 32.9-37.9%); from A. formoso by orbital diameter 12.3-17.3% of HL (vs. 8.3-8.7%), caudal peduncle depth 10.6-12.0% of SL (vs. 7.8-8.7%) and number of dentary teeth 38-78 (vs. 110); from A. multispinis and A. taunayi by occipital depth 18.8-22.0% of SL (vs. 16.2-18.0% and 17.3-17.9%, respectively); from A. mullerae by occipital depth 18.8-22.0% of SL (vs. 15.4-18.8%) and head length 37.8-41.4% of SL, mean = 38.9% (vs. 34.4-37.9%, mean= 36.3%) (Ref. 83296).