50650 Potamotrygon orbignyi (Castelnau, 1855) Potamotrygonidae River stingrays Potamotrygoninae Myliobatiformes Elasmobranchii Smooth back river stingray South America: Widespread in Amazon and Orinoco River basins and in river systems in Suriname, Guyana and French Guiana. AMNH 20913 Potamotrygon orbignyi AMNH 20914 Potamotrygon orbignyi AMNH 20915 Potamotrygon orbignyi AMNH 21994 Potamotrygon orbignyi AMNH 59870 1964 Potamotrygon reticulatus AMNH 56086 1983 Potamotrygon orbignyi AMNH 74547 1984 Potamotrygon orbignyi