The species complex <i>Astyanax fasciatus </i>Cuvier (Teleostei, Characiformes) – a multidisciplinary approach

Abstract

Cytogenetic data have provided important clues that the Astyanax fasciatus populations from the Upper Paraná River basin could be a part of a more diverse fish group, usually included on the same taxa. Samples collected in Cachoeira de Emas, SP, in Mogi‐Guaçu River basin, show two major cytotypes presenting 2 n = 46 and 2 n = 48 chromosomes, with distinct karyotypic formula, despite the fact that the molecular data suggested some degree of gene flow between these cytotypes. Cytogenetic and morphometric analyses were performed in this species, aiming to contribute to the understanding of the natural history from such fish group. Two allopatric populations with distinct standard cytotypes were analysed, and the data obtained suggest the separation into two groups.