Karyotypic characterization of Myleus micans (Lutken, 1875) (Pisces, Characidae, Serrasalminae)

Chromosomal data for Myleus micans, a species of the subfamily Serrasalminae endemic to the Sao Francisco river basin, Brazil, are presented for the first time, The diploid number was found to be 2n=58, with 26M+18SM+8ST+6A chromosomes for both sexes. Heterochromatin was seen in the pericentromeric region in few chromosomes, and in the telomeric region only in the 27 h pair. Multiple Ag-NORs were detected after silver nitrate staining, and located in four chromosomes. CMA(3) staining also revealed four chromosomes sites, two of them not coincinding with those evidenced by silver nitrate. On the other hand, seven 18S rDNA sites were seen after fluorescent in situ hybridization (FISH), and only one chromosome pair bearing the 5S rDNA genes. The relationships between Myleus and the other Serrasalminae genera are discussed.