Cytogenetic Studies and Evolutive Considerations in Species of the Calophysus Group (Siluriformes, Pimelodinae)

In this work, 2 species of the Pimelodidae family, Luciopimelodus pati and Pinirampus pirinampu, were cytogenetically analyzed. Specimens collected from the Parana River, near Corrientes city, Argentina, were assessed using conventional Giemsa, C-banding, and AgNOR staining. L. pati and P. pirinampu showed 2n=50 chromosomes. The cytogenetic characteristics of the 2 species could be considered as derivate features with respect to the other Pimelodinae fishes. Chromosome fusions and chromatin loss are proposed as the hypothetical origin of the described karyotypes.