Short-tailed river stingray

Short-tailed river stingray
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Myliobatiformes
Family: Potamotrygonidae
Genus: Potamotrygon
Species: P. brachyura
Binomial name
Potamotrygon brachyura

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 Himantura polylepis.

Growing to a disc diameter of about 1.5 m (5 ft) and a weight of 220 kg (490 lb), the short-tailed river stingray is the largest freshwater species in its family[3][4] 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, but it is also under pressure from habitat loss and occasionally caught for aquaria.[1][5][6]

Description

Short-tailed river stingrays are circular in shape and humped in the back.[7] The species can reach about 1.5 m (5 ft) in disc diameter and 220 kg (490 lb) in weight, making it the largest freshwater species in the family Potamotrygonidae (the discus ray Paratrygon aiereba can reach a slightly larger disc width, but weighs considerably less).[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 freshwated 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]

References

  1. 1 2 3 4 5 6 Charvet-Almeida, P., Soto, J.M.R. & Pinto de Almeida, M. (2009). "Potamotrygon brachyura". The IUCN Red List of Threatened Species. IUCN. 2009: e.T161687A5480430. doi:10.2305/IUCN.UK.2009-2.RLTS.T161687A5480430.en. Retrieved 15 January 2018.
  2. 1 2 Froese, Rainer and Pauly, Daniel, eds. (2017). "Potamotrygon brachyura" in FishBase. January 2017 version.
  3. 1 2 3 4 Oddone, M.C., G. Velasco & G. Rincon (2008). Occurrence of freshwater stingrays (Chondrichthyes: Potamotrygonidae) in the Uruguay River and its tributaries, Uruguay, South America. International Journal of Ichthyology 14 (2): 69-76.
  4. 1 2 Fishing World Records: Potamotrygon brachyura. Retrieved 14 January 2016.
  5. 1 2 3 4 5 Lucifora; Barbini; Vegh; Scarabotti; Vargas; Solari; Mabragaña; and Díaz de Astarloa (2016). "Geographic distribution of the short-tailed river stingray (Potamotrygon brachyura): assessing habitat loss and fishing as threats to the world's largest obligate freshwater elasmobranch". Marine and Freshwater Research. 67: 1463–1478. doi:10.1071/MF15003.
  6. 1 2 3 "Short-tailed river stingray". Discovery. Archived from the original on 7 January 2013.
  7. 1 2 River Monsters, First Edition, Da Capo Press, 2011, p. 165
  8. ↑ Last; White; de Carvalho; Séret; Stehmann; and Naylor, eds. (2016). Rays of the World. CSIRO. pp. 626 & 630. ISBN 9780643109148.
  9. ↑ River Monsters, First Edition, Da Capo Press, 2011, p. 162
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