Cytogenetic Characterization and NOR Polymorphism in Astyanax sp. C (Tetragonopterinae, Characidae) from the First Plateau of the Iguaçu River (Paraná State, Brazil)

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The characids belong to the greater freshwater fish family of the world with around 700 recognized species. Whithin this group the genus Astyanax includes several species with unclear phylogenetic relationships, showing a wide karyotypic diversity. In the highly endemic Iguaçu river basin these problems are also observed being distinguished 6 unnamed Astyanax species (A to F). In the present work were cytogenetically studied 2 populations of A. sp. C from the first plateau of the Iguaçu river (Paraná State, Brazil). Fishes of both populations are similar in chromosome number, having 2n=50, however were evidenced clear differences in C-banding and nucleolar organizing regions (NORs) patterns. With the use of the restriction enzyme Alu I were obtained the same results as C-bands. These results indicate the complexity of Astyanax and the importance of further taxonomic revisions joining morphological, cytogenetic and molecular approachings.