The Xingu River ray, River stingray, white-blotched river stingray, or polka-dot stingray (''Potamotrygon leopoldi'') is a species of

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

in the family

Potamotrygonidae River stingrays or freshwater stingrays are Neotropical freshwater fishes of the family (biology), family Potamotrygonidae in the Order (biology), order Myliobatiformes, one of the four orders of Batoidea, batoids, cartilaginous fishes related to ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Xingu River The Xingu River ( ; ; ) is a river in north Brazil. It is a southeast tributary of the Amazon River and one of the largest clearwater rivers in the Amazon basin, accounting for about 5% of its water. __TOC__ Description and history The fir ...

basin in

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

and as such prefers clear waters with rocky bottoms. It is sometimes kept in aquaria, like its more common relative the

Motoro Motoro is a god in Polynesian mythology, the tribal god of the Ngariki of Mangaia. He is the son of Tangiia and the brother of Ruanuku, Kereteki and Utakea. While travelling to Mangaia he argued with his two eldest brothers, was thrown into th ...

Etymology

The fish is named in honor of King Leopold III (1901–1983) of

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

, who sponsored many scientific studies at the Institut Royal des Sciences Naturelles de Belgique.

Description

''Potamotrygon leopoldi'' reaches up to in disc width, in total length and in weight. Females grow larger than males. It is closely related to the similar '' P. henlei'' from the

Tocantins River The Tocantins River ( , Parkatêjê dialect, Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan" and ''Ti'' for "beak"). It ...

basin and '' P. albimaculata'' from the

Tapajós River The Tapajós ( ) is a river in Brazil. It runs through the Amazon Rainforest and is a major tributary of the Amazon River. When combined with the Juruena River, the Tapajós is approximately long. Prior to a drastic increase in illegal gold mi ...

basin. Compared to ''P. henlei'', ''P. leopoldi'' is deeper black above and its underparts are mostly brownish-dusky (large white center to underparts of ''P. henlei''). Compared to ''P. albimaculata'', ''P. leopoldi'' has fewer and larger yellowish-white spots above. The River stingray is a venomous stingray that contains venom localized at its dentine spine in its tail. While the ray's venom composition does not change with maturation, the venom toxicity decreases as rays get older. On the other hand, rays' jaw shape, stiffness, and mineralization are strengthened with age, which allows mature rays the ability to consume hard-shelled invertebrates. These changes in traits with maturation reflect the different pressures rays experience in terms of functions such as feeding and avoiding predation during different maturity stages.

References

* leopoldi Freshwater stingrays of Brazil Endemic fish of Brazil Taxa named by Mariano N. Castex Taxa named by Hugo P. Castello Fish described in 1970 Articles containing video clips Taxonomy articles created by Polbot {{batoid-stub