This species is one of the most deep-bodied species of Australoheros with body depth in SL > 49%, a feature shared with A. guarani and A. facetus. It has been previously associated with A. kaaygua, but it is the sister species of A. minuano based on DNA characters. This species is distinguished from A. kaaygua by having less scale rows between anterior end of dorsal fin and upper lateral line, ch4 states 1-2 (vs. 0), by a very narrow or missing caudal base spot, by a pure yellow ground color (vs. yellowish-green), by yellow eyes (vs. dark green), by more scales between anterior end of dorsal fin and upper lateral line 5 (vs. 4), more anal fin spines 7 (vs. 6), more anal fin rays > 7 (vs. < 7), more dorsal fin rays (9 vs. 8), less E0 scales (24 vs. > 25), more L1 scales > 17-18 (vs. 16), less L2 scales 8 (vs. > 9), by a being more deep-bodied 49.6% SL (vs. 43.8%), and by having a shorter caudal peduncle 7.4% SL (vs. 10.4%). Australoheros angiru is distinguished from A. minuano by a large and dominant midlateral blotch, very narrow or missing caudal base spot, absence of a pinkish body coloration, small mouth terminal or subterminal (vs. large supraterminal), more scales between the anterior end of the dorsal fin and the upper lateral line, 5 (vs. 4), less anal fin rays, 7 (vs. 8), less dorsal fin rays, 9 (vs. 10), by slight differences in body depth 49.6% SL (vs. 46.9%) and in preorbital distance 7.3% SL (vs. 6.0%) (Ref. 87600).