Potamotrygonidae
Encyclopedia
River stingrays are Neotropical freshwater fishes of the Potamotrygonidae family
(order Myliobatiformes
).
They are native to 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
. Generally, each species is native to a single river basin, and the greatest species diversity
can be found in the Amazon
.
River stingrays are almost circular in shape, and range in size from Potamotrygon schuhmacheri, which reaches 25 centimetres (9.8 in) in diameter, to the Short-tailed river stingray
, P. brachyura, which grows up to 1.5 metres (4.9 ft) in diameter. 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 white spots.
They have a venomous caudal sting, and are one of the most feared freshwater fishes in the Neotropical region, sometimes more feared than piranha
s and electric eel
s. However, they are not dangerous unless stepped on or otherwise threatened.
River stingrays are the only family of batoids completely restricted to fresh water
habitats; while there are true freshwater species in the family Dasyatidae, for example Himantura chaophraya, the majority of species in this family are saltwater fish.
of the river stingrays is complex and undescribed
species remain.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
(order Myliobatiformes
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
).
They are native to northern, central and eastern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, living in rivers that drain into the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
, and into the Atlantic as far south as the Río de la Plata
Río de la Plata
The Río de la Plata —sometimes rendered River Plate in British English and the Commonwealth, and occasionally rendered [La] Plata River in other English-speaking countries—is the river and estuary formed by the confluence of the Uruguay River and the Paraná River on the border between Argentina and...
in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. Generally, each species is native to a single river basin, and the greatest species diversity
Species diversity
Species diversity is an index that incorporates the number of species in an area and also their relative abundance. It is a more comprehensive value than species richness....
can be found in the Amazon
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...
.
River stingrays are almost circular in shape, and range in size from Potamotrygon schuhmacheri, which reaches 25 centimetres (9.8 in) in diameter, to the Short-tailed river stingray
Short-tailed river stingray
The Short-tailed river stingray is a species of river stingray native to South America; they are known to inhabit Paraguay, Uruguay and Argentina basins...
, P. brachyura, which grows up to 1.5 metres (4.9 ft) in diameter. 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 white spots.
They have a venomous caudal sting, and are one of the most feared freshwater fishes in the Neotropical region, sometimes more feared than piranha
Piranha
A piranha or piraña is a member of family Characidae in order Characiformes, an omnivorous freshwater fish that inhabits South American rivers. In Venezuela, they are called caribes...
s and electric eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...
s. However, they are not dangerous unless stepped on or otherwise threatened.
River stingrays are the only family of batoids completely restricted to fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
habitats; while there are true freshwater species in the family Dasyatidae, for example Himantura chaophraya, the majority of species in this family are saltwater fish.
Species
The taxonomyTaxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of the river stingrays is complex and undescribed
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
species remain.
- Genus HeliotrygonHeliotrygonThe Round rays is a newly discovered genus of freshwater stingrays in the family Potamotrygonidae. The genus is endemic to the Amazon River and its tributaries in Brazil. It currently contains the following two species:...
Carvalho & Lovejoy, 2011- Heliotrygon gomesi Carvalho & Lovejoy, 2011 (Gomes's round ray)
- Heliotrygon rosai Carvalho & Lovejoy, 2011 (Rosa’s round ray)
- Genus Paratrygon A. H. A. Duméril, 1865
- Paratrygon ajereba (WalbaumJohann Julius WalbaumJohann Julius Walbaum was a physician, naturalist and taxonomist. He was the first to describe many previously unknown species from remote parts of the globe, such as the Great Barracuda , the Chum salmon from the Kamchatka River in Siberia, and the curimatá-pacú Johann Julius Walbaum (30 June...
, 1792) (Discus ray)
- Paratrygon ajereba (Walbaum
- Genus PlesiotrygonPlesiotrygonThe genus Plesiotrygon is a small genus of freshwater stingrays in the family Potamotrygonidae that are endemic to the major river systems of South America. It currently contains the following species:...
Rosa, Castello & Thorson, 1987- Plesiotrygon iwamae Rosa, Castello & Thorson, 1987 (Long-tailed river stingray)
- Plesiotrygon nana Carvalho & Ragno, 2011
- Genus PotamotrygonPotamotrygonPotamotrygon is a genus of freshwater stingrays native to the rivers of South America. As of July 2006, FishBase lists seventeen distinct species. The type species is P. hystrix....
Garman, 1877- Potamotrygon boesemani Rosa, Carvalho & Almeida Wanderley, 2008
- Potamotrygon brachyuraShort-tailed river stingrayThe Short-tailed river stingray is a species of river stingray native to South America; they are known to inhabit Paraguay, Uruguay and Argentina basins...
(Günther, 1880) (Short-tailed river stingray) - Potamotrygon constellata (VaillantLéon VaillantLéon Louis Vaillant was a French zoologist. He is most famous for his work in the areas of herpetology, malacology, and ichthyology...
, 1880) (Thorny river stingray) - Potamotrygon falkneri Castex & Maciel, 1963 (Largespot river stingray)
- Potamotrygon henlei (Castelnau, 1855) (Bigtooth river stingray)
- Potamotrygon humerosa Garman, 1913
- Potamotrygon hystrix (J. P. MüllerJohannes Peter MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
& HenleFriedrich Gustav Jakob HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1834) (Porcupine river stingray) - Potamotrygon leopoldi Castex & Castello, 1970 (White-blotched river stingray)
- Potamotrygon magdalenae (A. H. A. Duméril, 1865) (Magdalena river stingray)
- Potamotrygon marinae Deynat, 2006
- Potamotrygon motoro (J. P. MüllerJohannes Peter MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
& HenleFriedrich Gustav Jakob HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1841) (Ocellate river stingray) - Potamotrygon ocellata (Engelhardt, 1912) (Red-blotched river stingray)
- Potamotrygon orbignyi (Castelnau, 1855) (Smooth back river stingray)
- Potamotrygon schroederi Fernández-Yépez, 1958 (Rosette river stingray)
- Potamotrygon schuhmacheri Castex, 1964
- Potamotrygon scobina Garman, 1913 (Raspy river stingray)
- Potamotrygon signata Garman, 1913 (Parnaiba river stingray)
- Potamotrygon tatianae J. P. C. B. da Silva & Carvalho, 2011
- Potamotrygon tigrina Carvalho, Sabaj Pérez & Lovejoy, 2011
- Potamotrygon yepezi Castex & Castello, 1970 (Maracaibo river stingray)