Chromosome banding and synaptonemal complexes in Leporinus lacustris (Pisces, Anostomidae): analysis of a sex system.

Leporinus lacustris had been studied previously, and shows 2n = 54 metacentric and submetacentric chromosomes, including an XX/XY system described on the basis of Giemsa-stained preparations. However, there was some doubt regarding the identification of the sex chromosomes, because of the relative homogeneity of this species karyotype. Thus, the main goal of the present study was to find new evidence of heteromorphic sex chromosomes in these fish through chromosome banding and synaptonemal complex analyses. In fact, the data obtained do not support the presence of sexual heteromorphism. The importance of these methodologies in the study of fish sex chromosomes is discussed.