Occurrence of a metacentric macrochromosome B in different species of the genus Astyanax (pisces, characidae, tetragonopterinae)

Abstract

Several cases of B chromosomes have been described for neotropical fish species. In some fish groups, this occurrence is sporadic, whereas in others it is more frequent. A high frequency of a metacentric macrochromosome B has been reported for Astyanax scabripinnis populations from different locations. In the present study, this kind of chromosome is reported for the first time in 2 other species of the same genus, A. fasciatus and A. schubarti. This coincidence, as well as the differential B chromosome frequency among the 3 Astyanax species, permit some considerations about its probable common origin and further distribution in this fish group.