The karyotype of Apareiodon affinis (Pisces, Teleostei, Characiformes) from Sapucai River, Minas Gerais, Brazil

Abstract

Cytogenetic studies of 20 specimens of Apareiodon affinis (Pisces, Parodontidae) from Sapucai river, Minas Gerais State, Brazil, revealed distinct diploid numbers among sexes, the females showing 2n=55 and the males 2n=54 chromosomes, characterizing a multiple sex chromosome system of the ZZ/ZW 1W2 type. The nucleolar organizing regions were located in a terminal position on the long arm of a subtelocentric pair 26, which was coincident with GC-rich heterochromatin after CMA3 staining. Constitutive heterochromatin was observed in the pericentromeric position of all chromosomes and in the terminal position of about 7 chromosome pairs. A comparison with the available data is presented.