[摘要]：Six populations of Hoplias malabaricus from the Lower Paranapanema River were studied and showed 2n = 40 with metacentric/submetacentric chromosomes for females and 2n = 39 with m/sm chromosomes for males, thereby revealing a multiple sex chromosome system of the X1X1X2X2/X1X2Y type. The Y chromosome was the largest metacentric chromosome in all karyotypes. The heterochromatic blocks were located in a pericentromeric region of all pairs and in telomeric regions in some other pairs. A conspicuous pericentromeric C-band was detected in a single pair, equivalent to the X-1 chromosome. No markers on X-2 chromosomes were detected, but they could be identified by their size. The females displayed the same distribution of C and chromomycin A(3) bands and 18S rDNA sites among the populations. However, the males exhibited differences in both number and position of Giemsa C-bands on the Y chromosome, which were also evident after Chromomycin A 3 banding and FISH with the 18S rDNA probe. These cytogenetic tools allowed for the identification of possible mechanisms involved in the differentiation and evolution of the Y chromosome. Copyright (C) 2009 S. Karger AG, Basel
