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 signifi cant economic importance for the ornamental fi shing industry, being intensively captured, especially the species Potamotrygon leopoldi, which is endemic to this basin. In the attempt to propose a species-specifi c DNA marker for the species from Xingu, as well as ensuring a robust and reliable molecular identifi cation, the present work analysed mitochondrial gene portions Cytochrome Oxidase C -subunit I (COI) and Cytochrome B (Cytb) of fi ve 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 identifi ed as a species showed mitochondrial DNA from another, suggesting the fi rst 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 anew 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 identifi cation.

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“…It is a species with great international appeal within the ornamental fish trade, as it is among the most commercialized Potamotrygonidae species in Brazil, being exported to several countries in the world, mainly to the Asian, European, and North American (Charvet et al, 2018). It is listed as "Vulnerable" by the International Union for the Conservation of Natural Resources -IUCN (IUCN, 2023), and this status is justified due to the use of limited natural distribution, increasing pollution, loss of habitat associated with illegal mining and to the construction of the Belo Monte Hydroelectric Plant on the Xingu River (Sanches et al, 2021).…”