Identification key and pictures of the Hypostomus Lacpde, 1803 (Siluriformes, Loricariidae) from the rio Iva, upper rio Paran basin

The rio Ivaí flows through the left margin of the upper rio Paraná basin with 798 km of extension, being one of its largest tributaries. In this study, we analyzed 586 specimens of Hypostomus Lacépède, 1803 from the rio Ivaí basin deposited in the Coleção de Peixes do Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura da Universidade Estadual de Maringá (NUP) and Coleção Ictiológica do Grupo de Pesquisas em Limnologia e Recursos Pesqueiros (CIG). Herein, 14 species of Hypostomus were recorded from the rio Ivaí basin (10 already described and 4 possible new). The most representative species was H. ancistroides , corresponding to 23.5% of all the specimens, followed by Hypostomus sp. 3, with 15.2%, and Hypostomus sp. 2, with 13.8%. Considering Hypostomus , this study suggests that the rio Ivaí has high species richness compared with adjacent basins, such as rio Paranapanema, rio Tibagi, rio Piquiri and rio Iguaçu. Knowing the difficulties founded by many ichthyologists and researchers in identifying species within this genus, we also present here an identification key for its species present in the rio Ivaí basin.