Chromosome markers in Hoplias malabaricus (Characiformes, Erythrinidae): comparative cytogenetics among cytotypes

Abstract

Hoplias malabaricus is a neotropical freshwater fish that must correspond to a species complex. Conspicuous karyotypic diversification occurs among populations, with seven recognized cytotypes (A-G). Based on their general macrokaryotypic features, the cytotypes can be arranged in two major chromosomal groups, one composed by the cytotypes A, B, C, D (Cluster 1) and another by the cytotypes E, F, G (Cluster 2). The main purpose of this study is to improve the karyotypic data on the clustering of the cytotypes A-D in an evolutionary major group, using chromosome markers that include classic and molecular cytogenetic data (C-bands, Ag-NORs, fluorochrome positive sites, location of the ribosomal genes). It will also be looked to investigate the derivation of the cytotype D (2n=40/39 chromosomes in the females and the males, respectively, with a exclusive X1X1X2X2/X1X2Y sex chromosome system) from the cytotype C (2n=40 chromosomes, without a differentiated sex system). Thus, in a general way, it will be focused and analyzed the biodiversity of our ichthyofauna, particularly related to H. malabaricus, a fish group with problematic taxonomy and systematics. (AU)