Redescrição de Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) com a descrição de quatro novas espécies.

Abstract

Corydoras paleatus is a widely distributed species, occurring in the lower rio Paraná basin, south region of Brazil and Argentina, and coastal rivers in Uruguay and Brazil. The type-locality of this species is uncertain, as mentioned by Jenyns in the original description "the exact locality in South America in wich Mr. Darwin obtained this species is uncertain as the specimens have lost their attached labels", by this reason any exemplar with similar color pattern mentioned in the Jenyns' description is identified as Corydoras paleatus. However morphometric and genetical evidences shows that the populations attributed to C. paleatus may represent a complex of species. A comprehensive review analyzing specimens attributed to that species from several localities was carried out, considering available specimens of most Brazilian collections, additionally some collections from Argentina, Sweden and Uruguay. The analysis of the gathered material allowed the recognition of C. paleatus proper and four new species formerly identified as C. paleatus. Corydoras paleatus occurs below Itaipu dam, in the lower rio Paraná and rio Uruguay basin, and also in coastal basins of southern Brazil and Uruguay. Corydoras sp. A has wide geographical distribution, occurring in the upper and lower rio Paraná basin, rio Uruguay and coastal basins of southern Brazil and Uruguay. Corydoras sp. B is known to the lower rio Iguaçu basin, Corydoras sp. C to rio Pelotas basin and Corydoras sp. D from rio Bermejo basin. Coloration pattern, osteological features, proportions and counts are used to diagnose those species. A key for identification is provided, besides a map of geographic distribution and pictures of all species.