The lack of clarity regarding the taxonomy of the ocellate river stingray (Potamotrygon motoro) and the absence of previous studies regarding its genetic diversity and population structure makes this species vulnerable to overexploitation, being now the second species of freshwater ray most extracted and exported for ornamental purposes in Colombia. The aim of this work was to determine the population genetic structure and genetic diversity of P. motoro in the Colombian Amazon and Orinoco basins. A total of 110 samples collected from six sub-basins of the Orinoco and in two sub-basins of the Amazon, were analyzed by amplification and sequencing of two fragments of the mitochondrial genes, Cytochrome oxidase subunit I (COI) (532 bp), and Cytochrome b (Cytb) (429 bp). Haplotype networks were constructed, followed by an analysis of molecular variance (AMOVA). The most probable number of genetic groups (K) was evaluated by means of Bayesian inference using BAPS. One shared haplotype was found between the Colombian Amazon and Orinoco basins for COI but no shared haplotypes were found for Cytb. A K of 4 was found, differentiating three of the four units by sub-basins. A high and significant FST was found when comparing the two basins, suggesting significant genetic differentiation between basins for both mitochondrial gene fragments. These results suggest that P. motoro populations in Colombia should be managed as independent units in each basin for conservation and extraction purposes.
Keywords: Amazon; Colombia; Orinoco; cytochrome; cytochrome oxidase I; mitochondrial DNA; ornamental fish.