Autapomorphies of Astyanax pelegrini:

1. Length of caudal-fin canal of lateral line (93): (0> 1) almost reaching posterior margin of caudal fin. Paralleled in nodes 177 and 216 and in Tetragonopterus argenteus .

2. Number of gill rakers on first hypobranchial and ceratobranchial (195): (1> 0) 16 or more. Paralleled in nodes 177 and 183 and in Astyanax latens, A. cf. rutilus, Hoplias cf. malabaricus, Hyphessobrycon socolofi, Moenkhausia dichroura, Parecbasis cyclolepis, Piaractus mesopotamicus, and Stichonodon insignis .