Potamotrygonidae

{{Short description|Family of cartilaginous fishes}} {{Automatic taxobox | name = River stingrays | fossil_range = {{fossil range|Late Paleocene|present}} | image = Pfauenaugen-Stechrochen - Ocellate river stingray - Potamotrygon motoro.jpg | image_caption = Ocellate river stingray, ''Potamotrygon motoro'' | taxon = Potamotrygonidae | authority = Garman, 1877 | display_parents = 2 | subdivision_ranks = Genera | subdivision = ''Heliotrygon'' ''Paratrygon'' ''Plesiotrygon'' ''Potamotrygon'' ''Styracura'' | type_species = ''Potamotrygon histrix'' | type_species_authority = J. P. Müller & Henle, 1841 }}

'''River stingrays''' or '''freshwater stingrays''' are Neotropical freshwater fishes of the family '''Potamotrygonidae''' in the order Myliobatiformes, one of the four orders of batoids, cartilaginous fishes related to sharks. They are found in rivers in tropical and subtropical South America (freshwater stingrays in Africa, Asia and Australia are in another family, Dasyatidae). A single marine genus, ''Styracura'', of the tropical West Atlantic and East Pacific are also part of Potamotrygonidae. They are generally brownish, greyish or black, often with a mottled, speckled or spotted pattern, have disc widths ranging from {{convert|31|to(-)|200|cm|ft|1}} and venomous tail stingers. River stingrays feed on a wide range of smaller animals and the females give birth to live young. There are more than 35 species in five genera.<ref>{{Cite journal |last1=DE CARVALHO |first1=MARCELO R. |last2=LOVEJOY |first2=NATHAN R. |date=2011-02-24 |title=Morphology and phylogenetic relationships of a remarkable new genus and two new species of Neotropical freshwater stingrays from the Amazon basin (Chondrichthyes: Potamotrygonidae) |journal=Zootaxa |volume=2776 |issue=1 |doi=10.11646/zootaxa.2776.1.2 |issn=1175-5334}}</ref>

== Evolution == Potentially the oldest known member of the family is the extinct potential styracurine ''Atlantitrygon'', known from fossil teeth recovered from the Late Paleocene of Senegal.<ref name=":0">{{Cite journal |last=Sambou |first=Bernard Siguendibo |last2=Hautier |first2=Lionel |last3=Sarr |first3=Raphael |last4=Tabuce |first4=Rodolphe |last5=Lihoreau |first5=Fabrice |last6=Thiam |first6=Moustapha |last7=Lebrun |first7=Renaud |last8=Martin |first8=Jeremy E. |last9=Cappetta |first9=Henri |last10=Adnet |first10=Sylvain |date=2020-07-01 |title=Contribution to the reappraisal of the mid Paleogene ichtyofauna of Western Africa with three new enigmatical elasmobranchs from Thanetian–Lutetian of Senegal |url=https://www.sciencedirect.com/science/article/pii/S0753396920300215 |journal=Annales de Paléontologie |volume=106 |issue=3 |article-number=102400 |doi=10.1016/j.annpal.2020.102400 |issn=0753-3969}}</ref> The oldest definitive member of this family, and also the oldest from freshwater habitats, is ''Potamotrygon ucayalensis'' from the middle Eocene of Peru.<ref>{{Cite journal |last=Adnet |first=Sylvain |last2=Salas Gismondi |first2=Rodolfo |last3=Antoine |first3=Pierre-Olivier |date=2014-01-01 |title=Comparisons of dental morphology in river stingrays (Chondrichthyes: Potamotrygonidae) with new fossils from the middle Eocene of Peruvian Amazonia rekindle debate on their evolution |journal=Naturwissenschaften |language=en |volume=101 |issue=1 |pages=33–45 |doi=10.1007/s00114-013-1127-1 |issn=1432-1904}}</ref>

==Distribution and habitat== [[File:Potamotrygon adventure aquarium2.jpg|thumb|''Potamotrygon histrix'' is one of the most southernly distributed river stingrays, being found in the Río de la Plata Basin]]

They are native to tropical and subtropical northern, central and eastern South America, living in rivers that drain into the Caribbean, and into the Atlantic as far south as the Río de la Plata in Argentina. A few generalist species are widespread, but most are more restricted and typically native to a single river basin.<ref name=Rosa2010>{{cite book |author1=Rosa, R.S. |volume=20100521 |author2=Charvet-Almeida, P. |author3=Quijada, C.C.D. | year=2010 | chapter=Biology of the South American Potamotrygonid Stingrays | pages=241–285 |editor1=Carrier, J.C. |editor2=Musick, J.A. |editor3=Heithaus, M.R. | title=Sharks and Their Relatives II: Biodiversity, Adaptive Physiology, and Conservation | publisher=CRC Press | doi=10.1201/9781420080483-c5 |series=Marine Biology |doi-broken-date=12 July 2025 |isbn=978-1-4200-8047-6 }}</ref><ref name=Duncan2010>{{cite journal |author1=Duncan, W.P. |author2=M.N. Fernandes | title=Physicochemical characterization of the white, black, and clearwater rivers of the Amazon Basin and its implications on the distribution of freshwater stingrays (Chondrichthyes, Potamotrygonidae) | year=2010 | journal=PanamJAS | volume=5 | issue=3 | pages=454–464 }}</ref> The greatest species richness can be found in the Amazon, especially the Rio Negro, Tapajós, and Tocantins basins (each home to 8–10 species).<ref name=Carvalho2016b>{{cite journal | author = Carvalho M.R.d. | year = 2016 | title = Description of two extraordinary new species of freshwater stingrays of the genus ''Potamotrygon'' endemic to the rio Tapajós basin, Brazil (Chondrichthyes: Potamotrygonidae), with notes on other Tapajós stingrays | url = http://www.mapress.com/j/zt/article/view/zootaxa.4167.1.1/7705 | journal = Zootaxa | volume = 4167 | issue = 1| pages = 1–63 | doi=10.11646/zootaxa.4167.1.1| pmid = 27701358 | doi-access = free }}</ref> The range of several species is limited by waterfalls.<ref name=Rosa2010/>

Freshwaters inhabited by members of Potamotrygonidae vary extensively, ranging from lacustrine to fast-flowing rivers, in blackwater, whitewater and clearwater, and on bottoms ranging from sandy to rocky.<ref name=Rosa2010/><ref name=Duncan2010/> In at least some species juveniles tend to occur in shallower waters than adults.<ref name=Rosa2010/> Most species are strictly freshwater, but a few may range into brackish estuarine habitats in salinities up to at least 12.4‰.<ref name=Rosa2010/>

In 2016, two fully marine species formerly included in ''Himantura'' were found to belong in Potamotrygonidae, and moved to their own genus ''Styracura''.<ref name=Last2016>{{cite journal |author1=Last, P.R. |author2=Naylor, G.J. |author3=Manjaji-Matsumoto, B.M. |year=2016 |title=A revised classification of the family Dasyatidae (Chondrichthyes: Myliobatiformes) based on new morphological and molecular insights |journal=Zootaxa |volume=4139 |issue=3 |pages=345–368 |doi=10.11646/zootaxa.4139.3.2 |pmid=27470808}}</ref><ref name=Cavalho2016>{{cite journal |author1=Carvalho, M.R.d. |author2=Loboda, T.S. |author3=Silva, J.P.C.B.d. |year=2016 |title=A new subfamily, Styracurinae, and new genus, ''Styracura'', for ''Himantura schmardae'' (Werner, 1904) and ''Himantura pacifica'' (Beebe & Tee-Van, 1941) (Chondrichthyes: Myliobatiformes) |journal=Zootaxa |volume=4075 |issue=3 |pages=201–221 |doi=10.11646/zootaxa.4175.3.1|pmid=27811760 |bibcode=2016Zoot.41755.3.1C }}</ref> These are ''S. schmardae'' from the tropical West Atlantic, including the Caribbean, and ''S. pacifica'' from the tropical East Pacific, including the Galápagos.<ref name=Last2016/><ref name=Cavalho2016/>

Potamotrygonidae are the only family of rays mostly restricted to fresh water habitats.<ref>Compagno, L. J. V. & S. F. Cook (1995) "The exploitation and conservation of freshwater elasmobranchs: status of taxa and prospects for the future". In: ''The Biology of Freshwater Elasmobranchs''. Oetinger, M. I. & Zorzi, G. D. (eds.). ''Journal of Aquariculture & Aquatic Sciences'', '''7''': 62–90.</ref><ref name=Goes2004>{{cite journal |author1=Góes de Araújo, M.L. |author2=P. Charvet-Almeida |author3=M.P. Almeida |author4=H. Pereira | title=Freshwater Stingrays (Potamotrygonidae): status, conservation and management challenges | url=https://www.researchgate.net/publication/228945285 | year=2004 | journal=Information Document | volume=AC 20 | issue=8 | pages=1–6 }}</ref> While there are true freshwater species in the family Dasyatidae, for example ''Urogymnus polylepis'', the majority of species in this family are saltwater fish.<ref name=LastWhite2016>{{cite book|editor1=Last |editor2=White |editor3=de Carvalho |editor4=Séret |editor5=Stehmann |editor6=Naylor | title=Rays of the World | year=2016 | publisher=CSIRO | isbn=978-0-643-10914-8 }}</ref>

==Characteristics== [[File:Potamotrygon leopoldi.ogv|thumb|''Potamotrygon leopoldi'' is part of a species complex of blackish river rays with contrasting pale spots found in the Tapajós, Xingu and Tocantins basins<ref name=Carvalho2016b/>]] River stingrays are almost circular in shape, and range in size from ''Potamotrygon wallacei'', which reaches {{convert|31|cm|ft|abbr=on|1}} in disc width,<ref name=CarvalhoRosa2016>{{cite journal | author = Carvalho M.R.d., Rosa R.S., Araújo M.L.G. | year = 2016 | title = A new species of Neotropical freshwater stingray (Chondrichthyes: Potamotrygonidae) from the Rio Negro, Amazonas, Brazil: the smallest species of ''Potamotrygon'' | journal = Zootaxa | volume = 4107 | issue = 4| pages = 566–586 | doi=10.11646/zootaxa.4107.4.5| pmid = 27394840 | bibcode = 2016Zoot.41077.4.5C | url = http://publication.plazi.org/id/A508281FFF93FF8CFFEBCE629D11FFC1 }}</ref> to the chupare stingray (''S. schmardae''), which grows up to {{convert|2|m|ft|abbr=on}} in disc width.<ref name=FBschmardae>{{FishBase | taxon = Potamotrygonidae| species = schmardae | month = January | year = 2017}}</ref> The latter is one of only two marine species in this family (the other is ''S. pacifica'').<ref name=Last2016/><ref name=Cavalho2016/> The largest freshwater species in this family are the discus ray (''Paratrygon aiereba'') and short-tailed river stingray (''Potamotrygon brachyura''), which grow up to {{convert|1.5-1.6|m|ft|abbr=on}} in disc width.<ref name=LastWhite2016/><ref>{{cite journal | author = Oddone M.C., Velasco G., Rincon G. | year = 2008 | title = Occurrence of freshwater stingrays (Chondrichthyes: Potamotrygonidae) in the Uruguay River and its tributaries, Uruguay, South America | journal = International Journal of Ichthyology | volume = 14 | issue = 2| pages = 69–76 }}</ref> At up to {{convert|220|kg|lb|abbr=on}},<ref name=LastWhite2016/> by far the heaviest freshwater member of the family is the short-tailed river stingray, which among South American strict freshwater fish only is matched by the arapaima (''Arapaima'') and piraíba catfish (''Brachyplatystoma filamentosum'').<ref name=Lucifora2016>{{cite journal |author1=Lucifora |author2=Barbini |author3=Vegh |author4=Scarabotti |author5=Vargas |author6=Solari |author7=Mabragaña |author8=Díaz de Astarloa | title=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 | year=2016 | journal=Marine and Freshwater Research | volume=67 |issue=10 | pages=1463–1478 | doi=10.1071/MF15003 |bibcode=2016MarFR..10.1463L |s2cid=52245299 |hdl=11336/38346 |hdl-access=free }}</ref> In each species in the family Potamotrygonidae, females reach a larger size than the males.<ref name=Rosa2010/>

The upper surface is covered with denticles (sharp tooth-like scales). Most species are brownish or greyish and often have distinctive spotted or mottled patterns, but a few species are largely blackish with contrasting pale spots.<ref name=Carvalho2016b/><ref name=Carvalho2016a>{{cite journal | author = Carvalho M.R.d. | year = 2016 | title = ''Potamotrygon rex'', a new species of Neotropical freshwater stingray (Chondrichthyes: Potamotrygonidae) from the middle and upper rio Tocantins, Brazil, closely allied to ''Potamotrygon henlei'' (Castelnau, 1855) | journal = Zootaxa | volume = 4150 | issue = 5| pages = 537–565 | doi=10.11646/zootaxa.4150.5.2| pmid = 27615813 | url = http://publication.plazi.org/id/FF84FFA23061FF94FFC31E15FFF22E38 }}</ref> Juveniles often differ, in some species greatly, in colour and pattern from the adults.<ref name=Carvalho2016b/>

==Behavior== [[File:Potamotrygon national aquarium.jpg|thumb|''Potamotrygon henlei'' and its close relatives (e.g., ''P. leopoldi'') mainly feed on snails in the wild, but easily adapt to a more generalized diet in captivity<ref name=Rosa2010/><ref>{{cite journal |author1=Shibuya, A. |author2=M.L.G. Araújo |author3=J.A.S. Zuanon |year=2009 |title=Analysis of stomach contents of freshwater stingrays (Elasmobranchii, Potamotrygonidae) from the middle Negro River, Amazonas, Brazil |journal=Pan-American Journal of Aquatic Sciences |volume=4 |issue=4 |pages=466–475 }}</ref>]]

===Feeding=== Members of Potamotrygonidae are predators and feed on a wide range of animals such as insects, worms, molluscs, crustaceans and fish (even spiny catfish).<ref name=Rosa2010/> Plant material is sometimes found in their stomachs, but is likely ingested by mistake.<ref name=Rosa2010/> The exact diet varies with species; some are generalist predators and others are specialists. For example, ''Potamotrygon leopoldi'' mainly feeds on freshwater snails and crabs, although captives easily adapt to a generalist diet.<ref name=Rosa2010/><ref name=LastWhite2016/> The largest species such as ''Paratrygon'' are top predators in their habitat.<ref name=Rosa2010/> The jaw joints of stingrays are "loose", allowing them to chew their food in a manner similar to mammals.<ref>{{cite journal|author1=Kolmann, M.A. |author2=K.C. Welch Jr. |author3=A.P. Summers |author4=N.R. Lovejoy | year=2016 | title=Always chew your food: freshwater stingrays use mastication to process tough insect prey | journal=Proceedings of the Royal Society B | volume=283 | issue=1838 | doi=10.1098/rspb.2016.1392 |pmid=27629029 | article-number=20161392| pmc=5031661 |bibcode=2016PBioS.28361392K }}</ref> The family includes both species that are diurnal and species that are nocturnal.<ref name=Rosa2010/>

===Breeding=== [[File:Plesiotrygon iwamae underside (Buffalo Zoo).jpg|thumb|left|As in other rays, this ''Plesiotrygon iwamae'' is easily identified as male by its claspers, the pair of elongated structures at the base of the tail]] Like other Elasmobranchs, male freshwater stingrays are easily recognized by their pair of claspers, modifications of the pelvic fins used when mating. Mating occurs in a ventral-to-ventral position and the females give birth to live young.<ref name=Rosa2010/> While still in the mother's uterus, the developing embryo feeds on histotroph, a secretion produced by trophonemata glands.<ref name=Rosa2010/><ref name=Charvet2005>{{cite journal|author1=Charvet-Almeida, P. |author2=M.L. Góes de Araújo |author3=M. Pinto de Almeida | year=2005 | title=Reproductive Aspects of Freshwater Stingrays (Chondrichthyes: Patamotrygonidae) in the Brazilian Amazon Basin | journal= Journal of Northwest Atlantic Fishery Science| volume=35 | pages=165–171 | doi=10.2960/j.v35.m502| doi-access=free }}</ref><ref>{{cite journal|author1=Pedreros-Sierra, T.d.M. |author2=D.M. Arrieta-Prieto |author3=P.A. Mejía-Falla | year=2016 | title=Reproductive system of females of the Magdalena river endemic stingray Potamotrygon magdalenae: Anatomical and functional aspects | journal=Journal of Morphology | volume=277 | issue=5 | pages=680–697 | doi=10.1002/jmor.20527 |pmid=26968745 |bibcode=2016JMorp.277..680D |s2cid=36752114 }}</ref> Depending on exact species, the gestation period is 3 to 12 months and there are between 1 and 21 young in each litter.<ref name=Rosa2010/><ref name=Bleher2016>{{cite web|last1=Bleher | first1=H.yn | title=Definitive guide to South American freshwater rays | url=http://www.practicalfishkeeping.co.uk/features/articles/definitive-guide-to-south-american-freshwater-rays | date=13 June 2016 | publisher=Practical Fishkeeping | access-date=26 October 2017}}</ref> The breeding cycle is generally related to flood levels.<ref name=Charvet2005/>

==Relationship with humans== [[File:Potamotrygon motoro (Wroclaw zoo).JPG|thumb|When buried in the sand, stingrays such as this ''Potamotrygon motoro'' are barely visible (eye center-right on photo) and easily stepped on]]

===Sting=== {{Main|Stingray injury}} Like other stingrays, members of the family Potamotrygonidae have a venomous stinger on the tail (although it is harmless and vestigal or even absent in ''Heliotrygon'').<ref name=LastWhite2016/><ref>{{cite news|last1=Wheeler | first1=Quentin | title=New to Nature No 37: ''Heliotrygon'' stingrays | url=https://www.theguardian.com/science/2011/apr/10/heliotrygon-giant-stingray-amazon | date=10 April 2011 | work=The Guardian | access-date=25 October 2017}}</ref> There are generally one or two stingers, and they are periodically shed and replaced.<ref>{{cite journal|author1=Thorson, T.B. |author2=J.K. Langhammer |author3=M.I. Oetinger | year=1988 | title=Periodic shedding and replacement of venomous caudal spines, with special reference to South American freshwater stingrays, ''Potamotrygon'' spp. | journal=Environmental Biology of Fishes | volume=23 | issue=4 | pages=299–314 | doi=10.1007/bf00005241|bibcode=1988EnvBF..23..299T |s2cid=21482482 }}</ref> They are some of the most feared freshwater fishes in the Neotropical region because of the injuries they can cause.<ref name=fishbase>{{FishBase family | family = Potamotrygonidae | month = January | year = 2017}}</ref><ref>{{FishBase | genus = Potamotrygon | species = schuhmacheri | month = January | year = 2017}}</ref><ref>{{cite book | title = Complete Encyclopedia of the Freshwater Aquarium | author = Dawes, J. | publisher = Firefly Books Ltd. | location = New York | year = 2001 | isbn = 1-55297-544-4 }}</ref> In Colombia alone, more than 2,000 injuries are reported per year.<ref name=PotamotrygonDe>{{cite web|author=Grenard, S. | title=Stingray injuries, envenomation, and medical management | url=http://www.potamotrygon.de/fremdes/stingray%20article.htm | publisher=potamotrygon.de | access-date=22 October 2017 }}</ref> Freshwater stingrays are generally non-aggressive,<ref name=PotamotrygonDe/> and the stingers are used strictly in self-defense.<ref name=Silva2015>{{cite journal|author1=da Silva, N.J. Jr. |author2=K.R.C. Ferreira |author3=R.N.L. Pinto |author4=S.D. Aird | year=2015 | title=A Severe Accident Caused by an Ocellate River Stingray (Potamotrygon motoro) in Central Brazil: How Well Do We Really Understand Stingray Venom Chemistry, Envenomation, and Therapeutics? | journal=Toxins | volume=7 | issue=6 | pages=2272–2288 | doi=10.3390/toxins7062272 | pmid=26094699 | pmc=4488702 | doi-access=free }}</ref> As a consequence injuries typically occur when bathers step on them (injuries to feet or lower legs) or fishers catch them (injuries to hands or arms).<ref name=Silva2015/> In addition to pain caused by the barbed stinger itself and the venom, bacterial infections of the wounds are common and may account for a greater part of the long-term problems in stinging victims than the actual venom.<ref name=Silva2015/> The stings are typically highly painful and are occasionally fatal to humans, especially people living in rural areas that only seek professional medical help when the symptoms have become severe.<ref name=Silva2015/> In general, relatively little is known about the composites of the venom in freshwater stingrays, but it appears to differ (at least in some species) from that of marine stingrays.<ref name=Silva2015/> There are possibly also significant differences between the venoms of the various Potamotrygonidae species.<ref name=Reynolds2017/> Due to the potential danger they represent, some locals strongly dislike freshwater stingrays and may kill them on sight.<ref name=Bleher2016/> A study at the Butantan Institute, São Paulo, Brazil, revealed that the composition of freshwater stingray venom varies according to sex and age, even between individuals of the same species. Each time the environment changes, the feeding of the stingray changes, leading to changes in the composition of toxins and toxicological effects. There is no specific antidote or treatment for freshwater stingray venom.<ref>{{Cite web|title=Freshwater stingray venom varies according to sex and age|url=https://agencia.fapesp.br/freshwater-stingray-venom-varies-according-to-sex-and-age/30666/|access-date=2020-10-20|website=AGÊNCIA FAPESP|language=en}}</ref>

===Symptomatology=== Accidents occur when the rays are stepped on or when the fins are touched, the defensive behavior consists of turning the body, moving the tail and introducing the stinger into the victim. Generally, stingers are inserted into the feet and heels of bathers and the hands of fishermen. Initial symptoms include severe pain, erythema and edema, then necrosis occurs which results in sagging tissue in the affected area and forms a deep ulcer, which develops slowly. Systemic complications include nausea, vomiting, salivation, sweating, respiratory depression, muscle fasciculation and seizures. Once the stinger is torn during penetration into the skin, it can break and cause dentin fragments to be retained in the wound. The stinger can cause laceration, which results in secondary infection, usually caused by ''Pseudomonas'' and ''Staphylococcus''. If the stinger reaches internal organs, it can be fatal.<ref>{{cite thesis|author=Juliana Luiza Varjão Lameiras|date=24 May 2013|title=PERFIS PROTEICOS, ENZIMÁTICOS E MIOTOXICIDADE INDUZIDOS PELOS VENENOS DAS ARRAIAS AMAZÔNICAS ''Plesiotrygon iwamae'' Rosa, Castello & Thorson, 1987 E ''Potamotrygon motoro'' Müller & Henle, 1841 (Chondrichthyes – Potamotrygonidae) |trans-title=Protein, Enzyme and Mycotoxity Profiles Induced by Venom from the Amazonian Stingrays ''Plesiotrygon iwamae'' Rosa, Castello & Thorson, 1987 and ''Potamotrygon motoro'' Müller & Henle, 1841 (Chondrichthyes – Potamotrygonidae)|url=https://tede.ufam.edu.br/bitstream/tede/2622/1/Juliana%20Luiza%20Varj%C3%A3o%20Lameiras.pdf |publisher=Federal University of Amazonas|location=Manaus-AM|degree=|lang=pt-br}}</ref>

===As food=== Freshwater stingrays are often caught by hook-and-line and as bycatch in trawls. In the Amazon, ''Paratrygon'' and certain ''Potamotrygon'' are the most caught species and the first is the most sought.<ref name=Ramos2017>{{citation| author=Ramos, H.A.C. | date=May 2017 | title=Commercial species of freshwater stingrays in Brazil | publisher=Department of Sustainable Use of Biodiversity and Forests, Brazilian Institute of Environment and Renewable Natural Resources and Ministry of the Environment | pages=1–33 }}</ref> In the Río de la Plata region, the meat of ''P. brachyura'' is particularly prized and locally the species is called ''raya fina'' (fine ray).<ref>{{Cite iucn | author = Charvet-Almeida, P., Soto, J.M.R. & Pinto de Almeida, M. | title = ''Potamotrygon brachyura'' | volume = 2009 | article-number = e.T161687A5480430 | date = 2009 | doi = 10.2305/IUCN.UK.2009-2.RLTS.T161687A5480430.en }}</ref> Freshwater rays weighing less than {{convert|2|kg|lb|abbr=on}} are generally discarded, but have a low survival rate.<ref name=Ramos2017/> Their meat is mainly consumed locally, but is also exported to Japan and South Korea.<ref name=Ramos2017/> From 2005 to 2010, the reported capture in the Brazilian states of Amazonas and Pará has ranged between {{convert|584.5|and(-)|1104.5|metric ton|abbr=on}} per year.<ref name=Ramos2017/> In contrast, some fishers believe they only can be used for traditional medicine, incorrectly thinking that the meat (not just the tail region around the stinger) is toxic.<ref>{{cite journal|author1=Junior, H.J. |author2=J.L.C. Cardoso |author3=D.G. Neto | year=2013 | title=Injuries by marine and freshwater stingrays: history, clinical aspects of the envenomations and current status of a neglected problem in Brazil | journal=J. Venom Anim. Toxins Incl. Trop. Dis. | volume=19 | issue=16 | pages=2272–2288 | doi=10.1186/1678-9199-19-16 |pmid=23895313 | pmc=3735412 |doi-access=free }}</ref>

===In captivity=== [[File:Potamotrygon jabuti1.jpg|thumb|''Potamotrygon jabuti'' is a valuable species in the aquarium trade, but export of wild-caught individuals from Brazil (as opposed to captive bred) is illegal.<ref name=Ramos2017/>]]

Freshwater stingrays are often kept in aquariums, but require a very large tank and will eat small tank mates.<ref name=Bleher2016/><ref name=Reynolds2017>{{cite book|author1=Reynolds |author2=Hornbrook |author3=Stettner |author4=Terrell | title=Husbandry of freshwater stingrays |editor1=Smith |editor2=Warmolts |editor3=Thoney |editor4=Hueter |editor5=Murray |editor6=Ezcurra | year=2017 | series=Elasmobranch Husbandry |volume=Manual II | publisher=Special Publication of the Ohio Biological Survey | pages=99–112 | isbn=978-0-86727-166-9 }}</ref> Although generally non-aggressive, their venomous stinger represents a risk and on occasion aquarists have been stung.<ref>{{cite journal |author1=Brisset, I.B. |author2=A. Schaper |author3=P. Pommier |author4=L. de Haro | title=Envenomation by Amazonian freshwater stingray Potamotrygon motoro: 2 cases reported in Europe | year=2006 | journal=Toxicon | volume=47 | issue=1 | pages=32–34 | doi=10.1016/j.toxicon.2005.09.005 |pmid=16303158 |bibcode=2006Txcn...47...32B }}</ref> The ease of keeping varies significantly: Some such as ''Potamotrygon motoro'' are considered relatively hardy in a captive setting,<ref>{{cite web| title=Potamotrygon motoro | url=http://www.seriouslyfish.com/species/potamotrygon-motoro/ | publisher=SeriouslyFish | access-date=27 October 2017}}</ref> while others such as ''Paratrygon aiereba'', ''Plesiotrygon nana'' and ''Potamotrygon tigrina'' are much more difficult to maintain.<ref name=Reynolds2017/>

Several species are commonly bred in captivity, especially at East and Southeast Asian fish farms, which produce thousands of offspring each year.<ref name=Bleher2016/> The more serious captive breeding efforts only began in the late 1990s when Brazil put in restrictions on their export of wild-caught individuals.<ref name=Bleher2016/> Some captive farms produce hybrids (both intentionally to get offspring with new patterns and unintentionally because of a lack of males), but this practice is generally discouraged.<ref name=Bleher2016/><ref name=Reynolds2017/> In several US states there are regulations in place that limit the keeping of freshwater stingrays.<ref name=Reynolds2017/>

==Conservation== [[File:Potamotrygon tigrina (Tennessee Aquarium, Chattanooga).jpg|thumb|''Potamotrygon tigrina'' is an endangered species that only was scientifically described in 2011<ref>{{cite journal|last1=Carvalho|first1=M.R.d.|last2=Sabaj Pérez|first2=M.H.|last3=Lovejoy|first3=N.R.|year=2011|title=''Potamotrygon tigrina'', a new species of freshwater stingray from the upper Amazon basin, closely related to ''Potamotrygon schroederi'' Fernandez-Yépez, 1958 (Chondrichthyes: Potamotrygonidae) | journal=Zootaxa | volume=2827 | pages=1–30|doi=10.11646/zootaxa.2827.1.1}}</ref>]]

The status of most species is relatively poorly known, but overall it is suspected that river stingrays are declining due to capture (for food and the aquarium industry) and habitat loss (mainly due to dams and pollution from mining).<ref name=Ramos2017/>

Zoos and public aquariums in Europe and North America have initiated programs, including studbooks, for several Potamotrygonidae species.<ref name=Reynolds2017/><ref>{{cite web| title=Elasmobranch TAG News | url=http://euac.org/content/files/2017_no_1_faitag_news.pdf | date=1 March 2017 | publisher=Elasmobranch Taxon Advisory Group | access-date=27 October 2017 }}</ref>

===Dams=== [[File:Potamotrygon castexi.jpg|thumb|Some freshwater rays are threatened by dams, but ''Potamotrygon falkneri'' was able to spread to the upper Paraná basin due to the Itaipu Dam<ref name=JulioJunior/>]]

Dams represent a risk to some species, but others may benefit from them. For example, the Guaíra Falls disappeared after the completion of the Itaipu Dam, allowing ''Potamotrygon amandae'' (formerly misidentified as ''P. motoro'') and ''P. falkneri'' to spread into the upper Paraná basin.<ref name=JulioJunior>{{cite journal | doi = 10.1590/S1679-62252009000400021 | volume=7 | issue=4 | title=A massive invasion of fish species after eliminating a natural barrier in the upper rio Paraná basin | year=2009 | journal=Neotropical Ichthyology | pages=709–718 | author=Ferreira Júlio Júnior Horácio, Dei Tós Claudenice, Antonio Agostinho Ângelo, Simone Pavanelli Carla| doi-access=free }}</ref><ref name=Loboda2013/> When the Tucuruí Dam was completed, there was an increase in potential prey animals, allowing the population of ''P. henlei'' to increase.<ref>{{Cite iucn | author = Rincon, G. (SSG South America Regional Workshop, June 2003) | title = ''Potamotrygon henlei'' | volume = 2004 | article-number = e.T39402A10225965 | date = 2004 | doi = 10.2305/IUCN.UK.2004.RLTS.T39402A10225965.en }}</ref> In contrast, dams threaten some species such as ''P. magdalenae'' by isolating populations and preventing gene flow,<ref>{{Cite iucn | author = Lasso, C., Mesa-Salazar, L., Sanchez-Duarte, P., Usma, S. & Villa-Navarro, F. | title = ''Potamotrygon magdalenae'' | volume = 2016 | article-number = e.T161385A61472512 | date = 2016 | doi = 10.2305/IUCN.UK.2016-1.RLTS.T161385A61472512.en }}</ref> and others such as ''P. brachyura'' generally avoid lentic habitats, including the reservoirs created by river impoundment.<ref name=Lucifora2016/>

===Fishing and capture=== In addition to the large numbers caught for food (hundred of tons per year in the Brazilian Amazon alone),<ref name=Ramos2017/> many are killed because of the risk their stings represent to locals and tourists. In the Amazon, it has been estimated that many thousand river stingrays are removed from certain areas to minimize the risk to ecotourism.<ref name=Goes2004/> Such removal is unregulated by the authorities, as not considered fishing in the traditional sense.<ref name=Goes2004/>

Initially Brazil completely banned all exports of wild-caught freshwater stingrays for the aquarium trade, but have since introduced quotas for some species. From 2010 to 2015, between {{circa}} 4,600 and 5,700 of six species (the vast majority were ''P. leopoldi'' and ''P. wallacei''; the latter formerly referred to as ''P.'' cf. ''histrix'') were legally exported from Brazil per year.<ref name=Ramos2017/> The income generated from these are important to several small fishing communities.<ref name=Goes2004/><ref>{{cite web|last1=Tuccinardi | first1=M. | title=Rio Negro 'Hystrix' Stingray Gets a Name: Potamotrygon wallacei | url=https://www.reef2rainforest.com/2016/05/21/rio-negro-hystrix-stingray-gets-a-name-potamotrygon-wallacei/ | date=21 May 2016 | publisher=Reef to Rainforest Media | access-date=26 October 2017}}</ref> Other primary exporters of wild-caught freshwater stingrays are Colombia and Peru.<ref name=CITEScop15>{{citation| date=3–14 March 2013 | title=Listing of the species Potamotrygon motoro and Potamotrygon schroederi in Appendix II in accordance with Article II 2a (b) of the Convention, and Resolution Conf. 9.24 (Rev. CoP15) | publisher=Sixteenth meeting of the Conference of the Parties Bangkok (Thailand), CITES | pages=1–22 }}</ref> A level of illegal exports also occur,<ref name=Ramos2017/> and to curb this ''Paratrygon aiereba'' (in Colombia) and several ''Potamotrygon'' species (in Brazil and Colombia) have been included on CITES Appendix III.<ref>{{cite web| title=Appendices I, II and III | date=4 October 2017 | url=https://www.cites.org/eng/app/appendices.php | publisher=CITES | access-date=26 October 2017}}</ref> It has been suggested that all members of the family should be included on Appendix III, with ''Paratrygon'' and a few ''Potamotrygon'' species on Appendix II.<ref name=CITEScop15/><ref>{{cite web | title=17.246 to 17.249 Freshwater stingrays (Potamotrygonidae spp.) | url=https://cites.org/eng/dec/valid17/81884 | publisher=CITES | access-date=26 October 2017 | archive-date=28 October 2017 | archive-url=https://web.archive.org/web/20171028104957/https://cites.org/eng/dec/valid17/81884 }}</ref>

==Taxonomy and species== The taxonomy of the river stingrays is complex and undescribed species remain. The two species of ''Styracura'' were only moved to this family in 2016.<ref name=Cavalho2016/> Among the freshwater species, ''Heliotrygon'' and ''Paratrygon'' are sister genera, and ''Plesiotrygon'' and ''Potamotrygon'' are sister genera.<ref name=Carvalho2011>{{cite journal|title=''Morphology and phylogenetic relationships of a remarkable new genus and two new species of Neotropical freshwater stingrays from the Amazon basin (Chondrichthyes: Potamotrygonidae)''|author1=De Carvalho, M.R. |author2=N.R. Lovejoy |journal=Zootaxa|issue = 2776|pages=13–48|year=2011}}</ref>

Subfamily Styracurinae [[File:Himantura schmardae xelha.jpg|thumb|The two ''Styracura'' (here ''S. schmardae'') are the only members of the family from marine waters<ref name=Cavalho2016/>]] * Genus ''Styracura'' Carvalho, Loboda & da Silva, 2016 ** ''Styracura pacifica'' (Beebe & Tee-Van, 1941) (Pacific chupare) ** ''Styracura schmardae'' (Werner, 1904) (Chupare stingray)

Subfamily Potamotrygoninae * Genus ''Heliotrygon'' Carvalho & Lovejoy, 2011<ref name=Carvalho2011/> ** ''Heliotrygon gomesi'' Carvalho & Lovejoy, 2011 (Gomes's round ray) ** ''Heliotrygon rosai'' Carvalho & Lovejoy, 2011 (Rosa's round ray)

[[File:Paratrygon shedd.jpg|thumb|At up to {{convert|1.6|m|ft|abbr=on}} in disc width and {{convert|110|kg|lb|abbr=on}} in weight, ''Paratrygon aiereba'' is one of the largest species in the family<ref name=LastWhite2016/>]] * Genus ''Paratrygon'' A. H. A. Duméril, 1865 ** ''Paratrygon aiereba'' J. P. Müller & Henle, 1841 (Discus ray) ** ''Paratrygon orinocensis'' Loboda, Lasso, Rosa & De Carvalho, 2021 ** ''Paratrygon parvaspina'' Loboda, Lasso, Rosa & De Carvalho, 2021 ** ''Paratrygon raonii'' ''Loboda, 2026''<ref name=":1">{{Cite journal |last=Loboda |first=Thiago Silva |date=2026 |title=Four new species of neotropical freshwater stingrays of the genus Paratrygon (Myliobatiformes: Potamotrygonidae) from clear water rivers of the Amazon basin |url=http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252026000100226&tlng=en |journal=Neotropical Ichthyology |volume=24 |issue=1 |doi=10.1590/1982-0224-2025-0087 |issn=1982-0224}}</ref> ** ''Paratrygon munduruku'' Loboda, 2026<ref name=":1" /> ** ''Paratrygon araguaia'' Loboda, 2026<ref name=":1" /> ** ''Paratrygon lucindai'' Loboda, 2026<ref name=":1" />

[[File:Plesiotrygon iwamae (Buffalo Zoo).jpg|thumb|''Plesiotrygon'' (here ''P. iwamae'' with part of tail missing) is very long-tailed compared to other genera in the family<ref name=Carvalho2016b/>]] * Genus ''Plesiotrygon'' Rosa, Castello & Thorson, 1987 ** ''Plesiotrygon iwamae'' Rosa, Castello & Thorson, 1987 (Long-tailed river stingray) ** ''Plesiotrygon nana'' Carvalho & Ragno, 2011 (Black-tailed antenna ray)

[[File:Potamotrygon adventure aquarium.jpg|thumb|''Potamotrygon motoro'' is one of the best-known and most widespread species in the family]] * Genus ''Potamotrygon'' Garman, 1877 ** ''Potamotrygon adamastor'' J. P. Fontenelle & M.R. de Carvalho, 2017<ref name=Fontenelle2017>{{cite journal|author1=Fontenelle, J.P. |author2=M.R. de Carvalho | year=2017 | title=Systematic Revision of the Potamotrygon scobina Garman, 1913 Species-complex (Chondrichthyes: Myliobatiformes: Potamotrygonidae), with the Description of Three New Freshwater Stingray Species from Brazil and Comments on Their Distribution and Biogeography | journal=Zootaxa | volume=4310 | issue=1 |page=1 | doi=10.11646/zootaxa.4310.1.1}}</ref> ** ''Potamotrygon albimaculata'' M. R. de Carvalho, 2016 (Itaituba river stingray, Tapajós river stingray)<ref name=Carvalho2016b/> ** ''Potamotrygon amandae'' Loboda & M. R. de Carvalho, 2013<ref name=Loboda2013>{{cite journal | last1 = Loboda | first1 = T.S. | last2 = de Carvalho | first2 = M.R. | year = 2013 | title = Systematic revision of the ''Potamotrygon motoro'' (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin, with description of two new ocellated species (Chondrichthyes: Myliobatiformes: Potamotrygonidae) | journal = Neotropical Ichthyology | volume = 11 | issue = 4 | pages = 693–737 | doi = 10.1590/s1679-62252013000400001 | doi-access = free }}</ref> ** ''Potamotrygon amazona'' J. P. Fontenelle & M.R. de Carvalho, 2017<ref name=Fontenelle2017/> ** ''Potamotrygon boesemani'' Rosa, M. R. de Carvalho & Almeida Wanderley, 2008 (Boeseman's river stingray, emperor ray)<ref>{{cite journal|title=''Potamotrygon boesemani'' (Chondrichthyes: Myliobatiformes: Potamotrygonidae), a new species of Neotropical freshwater stingray from Surinam| author = Rosa, de Carvalho & Wanderley|journal=Neotropical Ichthyology|volume=6|issue = 1|pages=1–8|year=2008|doi=10.1590/S1679-62252008000100001|doi-access=free}}</ref> ** ''Potamotrygon brachyura'' (Günther, 1880) (Short-tailed river stingray) ** ''Potamotrygon constellata'' (Vaillant, 1880) (Thorny river stingray) ** ''Potamotrygon falkneri'' Castex & Maciel, 1963 (Largespot river stingray) ** ''Potamotrygon garmani'' J. P. Fontenelle & M.R. de Carvalho, 2017<ref name=Fontenelle2017/> ** ''Potamotrygon henlei'' (Castelnau, 1855) (Bigtooth river stingray) ** ''Potamotrygon humerosa'' Garman, 1913 ** ''Potamotrygon histrix'' (J. P. Müller & Henle, 1834) (Porcupine river stingray) ** ''Potamotrygon jabuti'' M. R. de Carvalho, 2016 (Pearl river stingray)<ref name=Carvalho2016b/> ** ''Potamotrygon leopoldi'' Castex & Castello, 1970 (White-blotched river stingray) ** ''Potamotrygon limai'' Fontenelle, J. P. C. B. da Silva & M. R. de Carvalho, 2014<ref name=Fontenelle2014>{{cite journal | author = Fontenelle J.P., Da Silva J.P.C.B., De Carvalho M.R. | year = 2014 | title = ''Potamotrygon limai'', sp. nov., a new species of freshwater stingray from the upper Madeira River system, Amazon basin (Chondrichthyes: Potamotrygonidae) | url =http://www.mapress.com/zootaxa/2014/f/z03765p268f.pdf | journal = Zootaxa | volume = 3765 | issue = 3| pages = 249–268 | doi=10.11646/zootaxa.3765.3.2| pmid = 24870898 }}</ref> ** ''Potamotrygon magdalenae'' (A. H. A. Duméril, 1865) (Magdalena river stingray) ** ''Potamotrygon marinae'' Deynat, 2006 ** ''Potamotrygon marquesi'' Silva & Loboda, 2019<ref name=Silva2019>{{cite journal | author1=Silva, J.P.C.B. | author2=T.S. Loboda | year=2019 | title=Potamotrygon marquesi, a new species of neotropical freshwater stingray (Potamotrygonidae) from the Brazilian Amazon Basin | journal=Journal of Fish Biology | volume=95 | issue=2 | pages=594–612 | doi=10.1111/jfb.14050 | pmid=31095730 | bibcode=2019JFBio..95..594C }}</ref> ** ''Potamotrygon motoro'' (J. P. Müller]& Henle, 1841) (Ocellate river stingray) ** ''Potamotrygon ocellata'' (Engelhardt, 1912) (Red-blotched river stingray) ** ''Potamotrygon orbignyi'' (Castelnau, 1855) (Smoothback river stingray) ** ''Potamotrygon pantanensis'' Loboda & M. R. de Carvalho, 2013<ref name=Loboda2013/> ** ''Potamotrygon rex'' Loboda & M. R. de Carvalho, 2016 (Great river stingray)<ref name=Carvalho2016a/> ** ''Potamotrygon schroederi'' Fernández-Yépez, 1958 (Rosette river stingray) ** ''Potamotrygon schuhmacheri'' Castex, 1964 (Parana River stingray) ** ''Potamotrygon scobina'' Garman, 1913 (Raspy river stingray) ** ''Potamotrygon signata'' Garman, 1913 (Parnaiba River stingray) ** ''Potamotrygon tatianae'' J. P. C. B. da Silva & M. R. de Carvalho, 2011 ** ''Potamotrygon tigrina'' [M. R. de Carvalho, Sabaj Pérez & Lovejoy, 2011 (Tiger ray)<ref>{{cite journal|title=''Potamotyrgon tigrina'', a new species of freshwater stingray from the upper Amazon basin, closely related to ''Potamotrygon schroederi'' Fernandez-Yepez, 1958 (Chondrichthyes: Potamotrygonidae)| author = de Carvalho, Perez & Lovejoy|journal=Zootaxa|volume=2827|pages=1–30|year=2011| doi = 10.11646/zootaxa.2827.1.1}}</ref> ** ''Potamotrygon wallacei'' M. R. de Carvalho, R. S. Rosa & M. L. G. Araújo, 2016 (Cururu ray)<ref name=CarvalhoRosa2016/> ** ''Potamotrygon yepezi'' Castex & Castello, 1970 (Maracaibo River stingray)

==References== {{Reflist}}

* Ross, Richard (1999) Freshwater Stingrays, Aqualog Special,p49 * Ross, Richard (2000) Freshwater Rays, Aqualog, p140

Category:Potamotrygonidae Category:Ovoviviparous fish Category:Articles containing video clips Category:Batomorphi families Category:Taxa named by Samuel Garman