Cytogenetical analyses in four species of the genus Astyanax (Pisces, Characidae) from Paraíba do Sul River Basin

Abstract

Cytogenetical data in four species of the genus Asytanax from Paraitinga river, Paraíba do Sul river basin, Brazil, are presented. Astyanax scabripinnis and Astyanax parahybae from other localities were previously cytogenetically described, however the karyotypes of Astyanax intermedius and Astyanax giton are described for the first time. A. scabripinnis, A. intermedius, and A. giton showed 2n=50 chromosomes, which are different from to A. parahybae, that presented 2n=48 chromosomes. The four species revealed multiple rDNA sites, as detected by silver nitrate staining and FISH-18S. The present data are discussed based on karyotypes and NOR peculiarities, biological aspects of the analyzed species, and their evolutionary consequences.

Key words:

• Karyotypic diversity
• Astyanax fish
• Paraíba do Sul river
• nucleolar organizer regions (NORs)
• fluorescent in situ hybridization (FISH)