Karyotypic studies in the Characidae fish, genus Astyanax. An endemic and highly isolated population of Astyanax sp.

Abstract

The chromosomes of Astyanax sp. is now described for the first time. Ten specimens of a highly isolated population from the Sinkhole 1 (Vila Velha State Park, Ponta Grossa, PR, Brazil) were analyzed, with the characterization of the karyotype, constitutive heterochromatin and nucleolar organizer regions. Males and females of this species present a similar karyotypic structure (2n = 48, 6M+18SM+14ST+10A), without morphologically differentiated sex chromosomes. A great variability concerning the heterochromatin located on the subtelo-acrocentric chromosomes appears also in this species, accordingly to that occur in some other Astyanax species.