Claim: Plesiotrygon, which is a big genus of freshwater stingrays in the family Potamotrygonidae, and under the order of Myliobatiforme, is known to be endemic to the Amazon basin, an area of about 6,300,000 km (2,400,000 sq mi).
Evidence: Plesiotrygon, the antenna rays, is a small genus of freshwater stingrays in the family Potamotrygonidae endemic to the Amazon basin in South America. Order: Myliobatiformes The Amazon drainage basin covers an area of about 6,300,000 km (2,400,000 sq mi), or about 35.5 percent of the South American continent.