The Nucleolar Organizer Regions of Erythrinidae Fish. An uncommon situation in the genus Hoplias

Abstract

A characterization of the Ag-NORs is presented for fish species of the Erythrinidae family, comprising the genera Hoplias, Hoplerythrinus and Erythrinus. A highly diversity was observed for the NORs sites, concerning their number and locations on the chromosomes, supporting the view that these regions underwent several chromosomal changes during the karyotypic evolution of this neotropical fish family. A particular situation occurs in the genus Hopliasmalabaricus group, where typical bitelomeric NORs can be seen in some biarmed chromosomes as a clearly populational feature, an infrequent situation in other fish groups or even among the vertebrates in general.