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(Received 7 July 2021; accepted 23 September 2021) Two new characid fish species are described from the upper rio Tocantins basin, Chapada dos Veadeiros, Goiás State, Brazil. Both species were discovered among specimens in museum collections. Relationships of taxa were evaluated in a more comprehensive phylogenetic analysis utilizing the largest dataset available of molecular and morphological data for the family Characidae. The two species were recovered as sister species and described in a new genus, closely related to Erythrocharax and Phycocharax. Dinotopterygium gen. nov. is distinguished from all other characid genera by the unique combination of ten synapomorphies, including the unique anal-fin morphology with a small number of branched anal-fin rays (13-16). Dinotopterygium uniodon sp. nov. and D. diodon sp. nov. differ by the number of tooth series in the premaxillary bone (one or two) and number of tooth cusps (7 or 5). The additional phenotypic variation for a taxonomically informative character within the Characidae through the discovery of new forms has helped to refine the interrelationship of the tribe Probolodini (Characidae: Stethaprioninae). The discovery of these new and possibly critically endangered species emphasizes the importance of museum collections for understanding biodiversity past and present. [ABSTRACT FROM AUTHOR]

Hyphessobrycon langeanii was originally described as endemic to the upper Araguaia river basin, Brazil. However, our analysis of several Hyphessobrycon specimens collected in the Correntes river basin and another tributary of the Itiquira River in Mato Grosso state (both belonging to the Paraguay river basin) reveals the first verified record of H. langeanii from this basin and from the states of Mato Grosso do Sul and Mato Grosso. The objective of this study is to provide a novel record of H. langeanii from the basin of the Paraguay River and from the state of Mato Grosso do Sul. We compare the newly discovered populations with the populations in the Araguaia river basin, and we also provide a brief discussion on the biogeography of this species. [ABSTRACT FROM AUTHOR]

Ectrepopterus uruguayensis Fowler was recently redescribed, with occurrence in lower tributaries of Río de la Plata and lower Río Uruguay, Uruguay. Herein its occurrence is extended and confirmed to Argentina, arroyo El Molino, in Uruguay Department, Entre Ríos Province, Uruguay drainage. [ABSTRACT FROM AUTHOR]