Natural Triploidy in Astyanax aff. scabripinnis (Pisces, Characidae) of the Tibagi river bay-PR

Abstract

The Astyanax aff. scabripinnis, of Apertados stream (PR), is characterized by a diploid number equal to 48 chromosomes (6M+22SM+4ST+16A). A female sample, however, showed 72 chromosomes being its karyotype constitute by 9M+33SM+6ST+24A, corresponding to a case of triploidy. In this triploid, the Ag-NORs showed more often in 4 chromosomes while the in situ hibridization (FISH) with 18Sr DNA probe showed 12 marked chromosomes, being that 3 chromosomes showed bitelomeric marks. The metaphases showed heterochromatin blocks in the telomeric regions in some acrocentric and subtelocentric chromosomes.