No abstract

Five rivers and 13 streams in the influence area of the Lajeado reservoir (upper-middle Tocantins River) were sampled in 5 expeditions. A total of 194 fish species were recorded and with the Characiformes and Siluriformes predominant, following the observed pattern for the Neotropical region. As expected, the families with greater richness were Characidae, Loricariidae and Cichlidae. Three species listed as Endangered were collected: Mylesinus paucisquamatus Jégu & Santos, 1988, Melanorivulus litteratus (Costa, 2010) and Paratrygon aiereba (Müller & Henle, 1841).

The first occurrence of Phallotorynus victoriae is reported from the Uruguay river basin associated with the grasslands of the Pampa Biome, southern Brazil. The record includes only one specimen from a tributary to Ibicuí River located in the municipality of Uruguaiana, Rio Grande do Sul state. Key wordsBiodiversity; Ibicuí basin; gonopodium; Pampa Biome; taxonomy.