First cytogenetic analysis of (Günther, 1860) by conventional and molecular methods with comments on the karyotypic evolution in Prochilodontidae.

We used conventional cytogenetic techniques (Giemsa, C-banding, Ag-NOR), and fluorescent hybridization (FISH) with 5S and 18S rDNA probes to investigate the karyotype and cytogenetic characteristics of (Günther, 1860) from Ecuador. The specimens studied have a karyotype with 2n=54 biarmed chromosomes (32 M + 22 SM) and C-positive heterochromatin located on the centromeric, pericentromeric, interstitial, and terminal regions of some chromosomes. The nucleolus organizer regions occurred terminally on the long arm of chromosome pair 2.