Karyotype similarities among two populations of Geophagus brasiliensis (Perciformes, Cichlidae) from the Tibagi river basin/PR/Brazil

Abstract

A cytogenetic study of G. brasiliensis was conducted in two populations from the Tibagi river basin/ PR. The diploid number was found to be 48 chromosomes and the fundamental number of 52. An AgNOR was observed on the short arm of a chromosome pair of the ST-A group, coinciding with the secondary constriction. This was seen in both populations, where in one of them there was a size heteromorphism of this region. Coincident results were found with chromomycin (CMA₃) staining and with fluorescence in situ hybridization using an 18S rDNA probe. Heterochromatin was distributed in the centromeric region in the majority of the chromosomes, as with the secondary constriction in both populations.

Key words:

• AgNOR
• C Banding
• CMA3 staining
• FISH
• Geophagus