9.0 cm SL (male/unsexed; (Ref. 38376))
This species belongs to the A. scabripinnis species complex and is distinguished from all species of this complex by the total number of pelvic-fin rays (7 vs. 8), except from A. brachypterygium Bertaco & Malabarba, A. ita Almirón, Azpelicueta & Casciotta, and A. obscurus (Hensel), Bertaco & Lucena (2010). It differs from A. brachypterygium by caudal peduncle length (14.1-18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0), by the number of caudal-peduncle scales (14 vs. 16), and by the number of cusps of the premaxillary inner series and the larger dentary teeth (4-5 vs. 5-7); from A. ita by the number of branched anal-fin rays (13-16 vs. 20-24), number of humeral spots (2 vs. 1), and by the orbital diameter (20.2-33.2% HL, mean = 27.4 vs. 38.6-42.0, mean = 40.2); and from A. obscurus by the number of maxillary teeth (2-5 vs. 1), number of lateral line scales (35-37, mean = 36 vs. 37-39, mean = 38), and by the number of branched anal-fin rays (13-16, mean = 14.7 vs. 16-21, mean = 18.3). Furthermore, the lower number of the branched anal-fin rays in A. goyanensis distinguish it from its congeners of the species complex, except from A. brachypterygium, A. cremnobates Bertaco & Malabarba, A. laticeps (Cope), A. intermedius Eigenmann, A. jenynsii (Steindachner), A. jordanensis Alcaraz, Pavanelli & Bertaco, A. microschemos Bertaco & Lucena, A. totae Haluch & Abilhoa, and A. varzeae Abilhoa & Duboc. It differs from most these species by the number of humeral spot (2 vs. 1), except A. brachypterygium, A. cremnobates, and A. varzeae. From these three species it differs by the number of cups in the premaxillary and dentary teeth (5-7 vs. 3-5), and by the caudal-peduncle length (14.1-18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0, 11.0-14.9, mean = 13.1, 10.5-13.9, mean = 12.4, respectively), and additionally from A. varzeae by the number of lateral line scales (35-37, mean = 36 vs. 37-42, mean = 39) (Ref. 84461).