Mitochondrial DNA suggests Hybridization in Freshwater Stingrays Potamotrygon (POTAMOTRYGONIDAE: MYLIOBATIFORMES) from the Xingu river, Amazonia and reveals speciation in Paratrygon aireba

Abstract

In the Xingu river basin, Brazil, occurs two genera of Potamotrygonidae family: Potamotrygon and Paratrygon. In this region, the taxa have significant economic importance for the ornamental fishing industry, being intensively captured, especially the species Potamotrygon leopoldi, which is endemic to this basin. In the attempt to propose a species-specific DNA marker for the species from Xingu, as well as ensuring a robust and reliable molecular identification, the present work analysed mitochondrial gene portions Cytochrome Oxidase C – subunit I (COI) and Cytochrome B (Cytb) of five species: P. leopoldi; Potamotrygon orbignyi; Potamotrygon motoro; Potamotrygon scobina and Paratrygon aiereba. We found haplotype sharing, with a total absence of reciprocal monophyly in the majority of taxa. Individuals morphologically identified as a species showed mitochondrial DNA from another, suggesting the first record of hybridization amongst freshwater stingrays of Xingu. Also, we detected a deep divergence among Paratrygon aiereba haplotypes, indicative of speciation, suggesting the possibility of a new species for the Xingu river. Therefore, although the is still confusing and controversial taxonomy of freshwater stingrays, and evidencing hybridization processes that may have shaped the evolutionary history of this Family, the genes COI and Cytb can successfully help in the their species identification.

Key words
Potamotrygonidae; Potamotrygon; Paratrygon aiereba; Xingu river