Potamotrygon rex

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Potamotrygon rex
Potamotrygon rex.png
Adult Potamotrygon rex (photo by Marcelo R. De Carvalho)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Myliobatiformes
Family: Potamotrygonidae
Genus: Potamotrygon
Species:
P. rex
Binomial name
Potamotrygon rex

Potamotrygon rex, the great river stingray, is a species of freshwater stingray belonging to the family Potamotrygonidae, native to South America in the Neotropical region. [1] [2] P. rex, along with some other Potamotrygon species form a sub-species group known as "black stingrays" known by their similar features and their locality to rivers draining the Central Brazilian Shield. Specifically, it is native to the Rio Tocantins in the central Brazilian state of Tocantins. It is quite a large organism, weighing up to 20 kg (44 pounds). Its appearance is dark brown to blackish with distinct clusters of yellow-orange spots around similarly colored ocelli on its dorsal side. Distinguishing features include broad pelvic-fin apices, lack of labial grooves, irregular double row of dorsal tail thorns, and having two angular cartilages associated with each hyomandibula.

Contents

Distribution

Native to the Neotropical regions of the mid and upper Rio Tocantins in the central Brazilian state of Tocantins. So far, it has not been found outside of these regions. [3]

Habitat and ecology

Potamotrygon rex is a neotropical freshwater stingray in the family Potamotrygonidae from the middle and upper Rio Tocantins, Brazil. It is benthopelagic, meaning that it lives at the bottom of the river. Potamotrygon rex, P. henlei, P. leopoldi and another new Potamotrygon species from the Rio Tapajós form a species-group (the "black stingrays") occurring in rivers draining the central Brazilian shield, characterized by their black to dark brown but highly ornate dorsal color, wide pelvic fins with broadly convex apices, among other features. Potamotrygon rex is the 25th species of Potamotrygon, and highlights that very large new species of fishes that still await discovery and description in the Neotropical region. [3]

Morphology

The genus Potamotrygon consists of freshwater stingrays that can be found in the rivers of South America. Potamotrygon rex is a large stingray species with a circular, almost oval-shaped disc. The top of the disc is very dark brown with yellow-orange spots in round clusters across the entirety of the disc. However, the density of these spots can vary from individual to individual and some exhibit one or two larger spots at the center of the clusters. The bottom of the disc can be dark grey to dark brown with yellowish-white spots. The density of these spots can also vary heavily based on the individual. The largest adult female was found to be 111 cm (3.6 ft) from anterior edge of the disc to the end of the tail, 75 cm (2.5 ft) from the anterior edge to the posterior edge of the disc, and 69 cm (2.3 ft) wide. Adult males are much smaller at around 82.5 cm (2.7 ft) from anterior edge of the disc to the end of the tail, 52.6 cm (1.7 ft) from the anterior edge to the posterior edge of the disc, and 47.5 cm (1.6 ft) wide. [3] Individuals larger than 100 cm can weigh up to 20 kg (44lbs). Like the rest of the species in the genus, Potamotrygon rex has venomous barbs at the end of its tail. Beginning at the base of the tail there are two rows of irregularly placed, semi-erect, sharp thorns that go down the length of the tail ending at the venomous barb. The stingray has a venom that causes painful inflammation at the site of the sting. The venom has been found to be more concentrated in females and more effective as the stingray ages. [4]

Conservation

Due to lack of knowledge and research on the species, there is limited information regarding the widespread distribution and population of Potamotrygon rex. Because of this, there are no current conservation efforts regarding the specific species of Potamotrygon rex. However, all species of freshwater stingray belonging to the genus Potamotrygon are listed in CITES Appendix III, which combats the illegal international trade of such animals. [5] The widespread protection of all Potamotrygon species is a basic step in the conservation of freshwater stingrays. Currently, other species of the Potamotrygon genus, Potamotrygon motoro and Potamotrygon falkneri, have been genetically analyzed to suggest the hybridization of such species in conservation efforts. [6] Considering the close morphological, geographic, and genetic similarities regarding Potamotrygon genus, similar studies may be applied to Potamotrygon rex.

Related Research Articles

<span class="mw-page-title-main">Stingray</span> Suborder of fishes

Stingrays are a group of sea rays, a type of cartilaginous fish. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae, Plesiobatidae, Urolophidae (stingarees), Urotrygonidae, Dasyatidae, Potamotrygonidae, Gymnuridae and Myliobatidae . There are about 220 known stingray species organized into 29 genera.

<span class="mw-page-title-main">Potamotrygonidae</span> Family of cartilaginous fishes

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. 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 31 to 200 centimetres (1.0–6.6 ft) 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.

<span class="mw-page-title-main">Long-tailed river stingray</span> Species of cartilaginous fish

The long-tailed river stingray or antenna ray is a species of freshwater stingray in the family Potamotrygonidae. It is found in the Amazon basin in South America, ranging from Ecuador to Belém. It lives in the main channel of the Amazon River and lower parts of its major tributaries.

<span class="mw-page-title-main">Ocellate river stingray</span> Species of cartilaginous fish

The ocellate river stingray, also known as the peacock-eye stingray or black river stingray, is a species of freshwater stingray in the family Potamotrygonidae. It was the first species to be described in the family and is also the most widespread, ranging throughout much of the Río de la Plata, Amazon, Mearim and Orinoco basins in tropical and subtropical South America. It is sometimes kept in aquaria.

<i>Potamotrygon</i> Genus of cartilaginous fishes

Potamotrygon is a genus of freshwater stingrays in the family Potamotrygonidae native to the rivers of South America, and sometimes seen in the aquarium trade. It inhabits rivers of tropical and subtropical climates, especially those of the Amazon basin and is virtually present in all South American countries, except for Chile.

<span class="mw-page-title-main">White-edge freshwater whipray</span> Species of cartilaginous fish

The white-edge freshwater whipray is an extremely rare species of stingray in the family Dasyatidae, native to four river systems in Southeast Asia. Measuring up to 60 cm (24 in) across, this ray has an oval pectoral fin disc and a very long, whip-like tail without fin folds. It can be identified by the presence of a sharply delineated white band running around the margin of its otherwise brown disc, as well as by its white tail and a band of dermal denticles along the middle of its back. This species feeds on benthic invertebrates and is aplacental viviparous. Its two long tail spines are potentially dangerous to humans. The International Union for Conservation of Nature (IUCN) has assessed the white-edge freshwater whipray as Endangered, as it is under heavy pressure from fishing and habitat loss, degradation, and fragmentation.

<span class="mw-page-title-main">Bigtooth river stingray</span> Species of cartilaginous fish

The bigtooth river stingray or Tocantins River ray is a species of freshwater fish in the family Potamotrygonidae. It is endemic to the lower Tocantins basin and Araguaia basin in Brazil, and prefers muddy bottoms. It is sometimes kept in aquaria. This stingray is generally common and its population increased after the Tucuruí Dam was completed, unlike many other species in its range.

<span class="mw-page-title-main">Xingu River ray</span> Species of cartilaginous fish

The Xingu River ray, River stingray, white-blotched river stingray, or polka-dot stingray is a species of freshwater fish in the family Potamotrygonidae. It is endemic to the Xingu River basin in Brazil and as such prefers clear waters with rocky bottoms. It is sometimes kept in aquaria, like its more common relative the Motoro.

The raspy river stingray, mosaic stingray or arraia is a species of freshwater fish in the family Potamotrygonidae. This stingray is endemic to the Amazon basin in Brazil, where known from the Amazon–Pará River, the Madeira River basin, Uatumã River and lower Tocantins River.

<span class="mw-page-title-main">Porcupine river stingray</span> Species of cartilaginous fish

The porcupine river stingray is a species of river stingray in the family Potamotrygonidae, the type of the Potamotrygon genus. It is found in the basins of the Paraná and Paraguay River basins in South America. Most chemical weathering of minerals seems to take place in the upland drainage basins rather than on the floodplains, and most major solutes display conservative mixing in the river-floodplain system. The population in the Rio Negro basin was described as a separated species, P. wallacei, in 2016.

<span class="mw-page-title-main">Short-tailed river stingray</span> Species of cartilaginous fish

The short-tailed river stingray is a species of river stingray native to the Río de la Plata Basin in South America. It is sometimes known as the giant freshwater stingray, but this name is typically used for Urogymnus polylepis.

Heliotrygon is a genus of freshwater stingrays in the family Potamotrygonidae. The genus is endemic to the Amazon basin in South America. Despite being discovered decades earlier, the genus was only scientifically described in 2011. They mainly live in deep river channels, but approach the shore at night to feed on fish.

Heliotrygon rosai, or Rosa's round ray, is a species of freshwater fish in the family Potamotrygonidae. It is native to the Amazon basin in South America. Its maximum disc width is 80 cm (2.6 ft) and the stinger is greatly reduced, rendering it virtually harmless. It has not been evaluated by the IUCN red list.

Potamotrygon tatianae, the Tatiana's river stingray, is a species of river stingray (Potamotrygonidae) endemic to the Madre de Dios River and upper Madeira River basins in Peru.

Heliotrygon gomesi, or Gomes's round ray, is a species of freshwater stingray native to the western Amazon basin in South America, specifically Brazil. It is the type species of its genus. It spends the day in deep river channels, but moves closer to the shore at night to feed.

<i>Potamotrygon falkneri</i> Species of cartilaginous fish

Potamotrygon falkneri, the largespot river stingray or reticulated freshwater stingray, is a species of freshwater stingray in the family Potamotrygonidae from tropical and subtropical South America. It is sometimes seen in the aquarium trade, but requires a very large tank.

<i>Potamotrygon tigrina</i> Species of cartilaginous fish

Potamotrygon tigrina, also known as the tiger river stingray, is a species of freshwater ray in the family Potamotrygonidae. This endangered species is endemic to black- and whitewater rivers in the upper Amazon basin in northeastern Peru. It is sometimes kept in aquariums and has been bred in captivity, but it is generally a sensitive species.

Rhinebothriidea is an order of Cestoda (tapeworms). Members of this order are gut parasites of stingrays.

Plesiotrygon nana, the black-tailed antenna ray, is a species of freshwater stingray in the family Potamotrygonidae. It is native to the western Amazon basin in northeastern Peru, western Brazil, southeastern Colombia, and possibly eastern Ecuador. It is found both in the mainstream of the Amazon and Putumayo Rivers and in smaller tributaries such as the Itaya and Pachitea Rivers. It is occasionally kept in aquariums and has been bred in captivity, but it is sensitive and the tail is easily damaged.

<span class="mw-page-title-main">Animal attacks in Latin America</span>

List of reported attacks and species involved in Latin America.

References

  1. "Potamotrygon rex". www.gbif.org. GBIF . Retrieved 2020-11-04.
  2. Monteiro Dos Santos, Juliane; Cardoso Dos Santos, Janaína; Marques, Elineide Eugênio; Araújo, Gessi Carvalho de; Seibert, Carla Simone; Lopes-Ferreira, Mônica; Lima, Carla (May 2019). "Stingray (Potamotrygon rex) maturity is associated with inflammatory capacity of the venom". Toxicon: Official Journal of the International Society on Toxinology. pp. 74–83. doi:10.1016/j.toxicon.2019.03.013. PMID   30898532 . Retrieved 2020-11-04.
  3. 1 2 3 De Carvalho, Marcelo R., 2016: 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). Zootaxa 4150 (5): 537-565
  4. Dos Santos, J.M., Dos Santos J.C., Marques, E.E., De Araujo, G.C., Seibert, C.S., Lopes-Ferreira, M.,Carla, L., 2019. Stingray (Potamotrygon rex) maturity is associated with inflammatory capacity of the venom. Toxicon Vol. 163, pg 74-83
  5. Morales-Gamba, Caldas. “Sperm Characterization of the Amazonian Freshwater Cururu Stingray Potamotrygon wallacei (Potamotryogonidae): Basic Knowledge for Reproduction and Conservation Plans.” Zygote (Cambridge), vol. 27, no. 4, Cambridge University Press, Aug. 2019, pp. 259–61, doi:10.1017/S096719941900039X.
  6. Cruz, Cruz. “First Identification of Interspecies Hybridization in the Freshwater Stingrays Potamotrygon Motoro and P. Falkneri (Myliobatiformes, Potamotrygonidae).” Conservation Genetics, vol. 16, no. 1, Springer Netherlands, Feb. 2015, pp. 241–45, doi:10.1007/s10592-014-0642-8.