Five new species of genus Astyanax Baird & Girard, 1854 from Rio Iguacu, Parana, Brazil (Ostariophysi, Characiformes, Characidae)

Five new species of the Neotropical characiform genus Astyanax Baird & Girard are described from Rio Iguacu at the border of Parana and Santa Catarina states, southeastern Brazil and Astyanax gymnogenis Ligenmann is redescribed Each new species can be distinguished from all other Astyanaz species from the upper Rio Parana bastin by exclusive combinations of tooth shape number of dental cuspids distance between third infraorbital and preopercle, number of lateral line scales, longitudinal series of scales number of gill rakers and differences from shape of body and head traits This study proposes the species of genus Astyanax from Rio Iguacu as probably endemic, since all of them are absent from tributaries of the Rio Parana hydrographic system The high degree of diversification acquired by those Astyanax species in the Iguacu basin may perhaps be allied to the long isolation period of this river from the Rio Parana basin caused by the Iguacu waterfalls This barrier probably isolated those basins resulting in original groups of Characiformes and then Astyanax species, both isolated from one another and both different from their relatives in neighbouring basins