Autapomorphy of Astyanax abramis:

1. Length of medial bony ridge of opercle (170): (1> 0) 60% or greater than opercular length. Paralleled in the Serrasalmidae, in node 210, and in Creagrutus cf. taphorni, Hoplias cf. malabaricus, and Roeboides microlepis . Some trees: Paralleled in Acestrorhynchus pantaneiro and Salminus brasiliensis .