The short-tailed river stingray (Potamotrygon brachyura) is a species of river stingray (family Potamotrygonidae) native to the Río de la Plata Basin in South America.[2][3] It is sometimes known as the giant freshwater stingray,[1] but this name is typically used for the southeast Asian Urogymnus polylepis.
| Short-tailed river stingray | |
|---|---|
 | |
| Juvenile | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Superorder: | Batoidea |
| Order: | Myliobatiformes |
| Family: | Potamotrygonidae |
| Genus: | Potamotrygon |
| Species: | P. brachyura |
| Binomial name | |
| Potamotrygon brachyura (Günther, 1880) | |
Growing to a disc diameter of about 1.9 m (6.2 ft) and a weight of 220 kg (490 lb), with unconfirmed records of even larger specimens,[4] the short-tailed river stingray is the largest freshwater species in its family[3] and one of the heaviest strict freshwater fish in South America, only matched by the arapaima (Arapaima) and piraíba catfish (Brachyplatystoma filamentosum).[5] The primary threat to the short-tailed river stingray is fishing for food and as a game fish (if not released), but it is also under pressure from habitat loss and occasionally caught for aquaria.[1][5][6]
Description
The short-tailed river stingray is circular in shape and humped in the back.[7] The species can reach about 1.9 m (6 ft) in disc diameter and 220 kg (490 lb) in weight, making it the largest freshwater species in the family Potamotrygonidae.[3][4][8] They have a dark pattern on their backs, probably used as camouflage.[7] The ray's tail is very muscular and thick, covered with short spines at the base and a venomous sting at the end.[9]
Distribution
The short-tailed river stingray is found in the Río de la Plata Basin, including the Paraguay, Paraná and Uruguay Rivers in the countries of Argentina, Brazil, Paraguay and Uruguay.[1][2][3] It may also range into Bolivia in the Pilcomayo River (a tributary of the Paraguay River), but this remains unconfirmed.[5] In the north it ranges from the upper Paraguay River basin, including the Pantanal, and south to the lowermost freshwater sections of the Río de la Plata.[5] Unlike some other freshwater rays, it has not been able to spread to the upper Paraná River basin after the Itaipu Dam flooded the Guaíra Falls, which represented a natural barrier to its range.[5]
Lifestyle
Female short-tailed river stingrays give birth to up to 19 fully formed young stingrays per litter.[1][6] The pups start off eating plankton and then move on to consume small mollusks, crustaceans, the larvae of aquatic insects, and fish.[1][6]