Identification key of Probolodus

1. Perforated scales on the lateral line 45-56 (48 most frequent); 18-21 scale series around the caudal peduncle (18 most frequent); 34-35 totals vertebrae (35 most frequent) .................................................................. P. heterostomus (Figs. 2, 3) (rio Paraíba do Sul basin)

1’. Perforated scales on the lateral line 36-43; 14-16 scale series around the caudal peduncle (14 most frequent); 33-36 totals vertebrae (33 and 34 are most frequent) .............................. 2

2. Seven or eight transverse series of scales from insertion of pelvic fin to lateral line (seven most frequent, eight infrequent); 13-16 scales along middorsal line between posterior terminus of base of dorsal fin and adipose fin (15 most frequent) .............................................. P. oyakawai (Figs. 2, 5) (rio Ribeira de Iguape basin)

2’.Six transverse series of scales from insertion of pelvic fin to lateral line; 12 scales along middorsal line between posterior terminus of base of dorsal fin and adipose fin ............................................................................. P. sazimai (Figs. 2, 7) (tributaries of the rio Itapemirim and drainages of the rio Doce basin)