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.

A redescription of Hypostomus hermanni is presented herein along with the description of a new species of Hypostomus, which is apparently endemic to the Ivaí River basin, a tributary of the Upper Paraná River basin, Brazil. Hypostomus hermanni is diagnosed from congeners mainly by having: usually large black blotches on body and fins; absence of keels on compound pterotic, on pre-dorsal plates, and on lateral series of bony plates; by having parieto-supraoccipital and predorsal region flat; and by having less than 46 teeth per each premaxilla or dentary ramus. The new species is distinguished from congeners mainly for lacking conspicuous blotches, parieto-supraoccipital non-carinate, and villiform bicuspid teeth.

Abstract:The Rio Pitangueira and the Ribeirão Santa Terezinha are right margin affluents of the Rio do Peixe, upper Rio Paraná basin, São Paulo state, Brazil. Fourteen non-temporally standardized samplings were made at four sampling sites along the Rio Pitangueira and at one sampling site on Ribeirão Santa Terezinha using cast nets, trawl net, hand net, and fishing rod and hook. Thirty fish species were collected, belonging to five orders, 13 families, and 25 genera. Of these, one is probably new to science and one is a rare species.

In the present study, we describe two new species of Curculionichthys from rio Tapajós and rio Tocantins basins in Brazil. Both species present all diagnostic features of Curculionichthys. Furthermore, both species C. tukana and C. itaim are distinguished from congeners by the combination of seven characters: (1) a higher number of plates in abdominal lateral plates series; (2) the absence of large conspicuous odontodes forming rows on head and trunk; (3) the anterior profile of the head pointed; (4) a higher number of dentary teeth; (5) the lack of contrasting dark spots at the anterodorsal region of body; (6) the absence of an irregular concentration of chromatophores that entirely cover the anal-fin origin and adjacent region, and distal portion of the first unbranched anal-fin ray; and (7) the presence of odontodes forming aligned rows, more evident in the dorsal portion of head and in the lateral portion of caudal peduncle. Furthermore, C. tukana can be further distinguished from congeners by three characters: (1) the papillae aligned in series that extends from the distal portion of lower lip to dentary; (2) the absence of dark-brown spots scattered over the body; and (3) a higher number of maxillary teeth. The species C. itaim also can be further distinguished from congeners by five characters: (1) the papillae randomly distributed throughout the lower lip; (2) a smaller number of medial plates series on lateral portion of the body following the lateral line; (3) a smaller number of median plates series in abdomen; (4) the absence of dark-brown spots scattered over the body; and (5) the absence of one unpaired platelet on the dorsal portion of the caudal peduncle.

A new species of Hisonotus from rio Juma, located at the right margin of the lower rio Aripuanã, rio Madeira basin is described. The new species is distinguished from its congeners mainly by a reddish-tipped premaxillary and dentary teeth, a V-shaped spinelet, three lateral plates in abdominal series, the coloration pattern of caudal fin with three transversal dark bars, and by morphometric characters.