Background and aims: We analyzed a small and wide geographically distributed Neotropical freshwater fish, the Piabina argentea from the Upper Paraná Basin, to check the hypothesis that this species is composed of more than one biological unit, since it has a limited dispersion, through the DNA barcode technique.
Materials and methods: Partial mitochondrial COI and CytB gene sequences were obtained for 58 specimens drawn from 13 localities.
Results: Phylogenetic analysis revealed six major clusters of P. argentea. Kimura-two-parameter (K2P) genetic divergences among these six P. argentea clusters ranged from 2 to 5.6% and from 2.3 to 5.4% for COI and CytB genes, respectively, and these values were on average approximately nine times greater than intra-cluster K2P divergences. The fixation index (F(ST)) among clusters showed very high values and the haplotype network analysis displayed seven unconnected units.
Conclusion: These results reinforce the hypothesis that the widely distributed P. argentea species concept as currently conceived actually represents more than one species (possibly six). These results demonstrate the efficacy of DNA barcoding for the discovery of hidden diversity in Neotropical freshwater fishes, and we conclude that barcoding is a useful tool for alpha taxonomy.