ABSTRACT
This chapter explains the karyotypic diversity in the family Erythrinidae, particularly concerning Hoplias malabaricus, Hoplerythrinus unitaeniatus and Erythrinus erythrinus, which exhibit an extensive chromosome evolution associated with numerical and structural rearrangements. Erythrinidae is a relatively small Characiformes family endemic to South America, with representatives broadly distributed throughout the Brazilian basins. Erythrinidae species are found in several habitats, right from small lakes and lagoons to large rivers, with a carnivorous diet. In fact, the taxonomy and systematics of the Erythrinidae family are still poorly defined, and what is currently known on this group certainly does not correspond to reality. Hoplerythrinus is a small erythrinid genus, represented by H. cinereus and H. gronovii, with restricted distribution, and H. unitaeniatus, with a broader distribution through South America. The presence of distinct sex chromosome systems among the Erythrinidae fish, which appear to have differentiated from separate events, such as heterochromatin accumulation, translocations and centric fusions on different chromosomes, is outstanding.
