The Xingu River ray, white-blotched river stingray, or polka-dot stingray (Potamotrygon leopoldi) 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.[1] It is sometimes kept in aquaria, like its more common relative the Motoro.[1]
Potamotrygon leopoldi reaches up to 40 cm (16 in) in disc width,[4] 75 cm (30 in) in total length and 20 kg (44 lb) in weight.[5] Females grow larger than males.[6] It is closely related to the similar P. henlei from the Tocantins River basin and P. albimaculata from the Tapajós River basin.[7] 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).[7][8] Compared to P. albimaculata, P. leopoldi has fewer and larger yellowish-white spots above.[7][8]
The Xingu river ray is a venomous stingray that contains venom localized at its dentine spine in its tail.[9] While the ray's venom composition does not change with maturation, the venom toxicity decreases as rays get older.[9] 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.[10] 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.[9]
References
^ a b cCharvet, P., Torres, Y.T.P., Santana, F.M. & Sayer (2022). "Potamotrygon leopoldi". IUCN Red List of Threatened Species. 2022: e.T39403A2923696. doi:10.2305/IUCN.UK.2022-2.RLTS.T39403A2923696.en. Retrieved 9 December 2022.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Christopher Scharpf & Kenneth J. Lazara (22 September 2018). "Order MYLIOBATIFORMES (Stingrays)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Retrieved 11 November 2021.
^Froese, Rainer; Pauly, Daniel (eds.) (2017). "Potamotrygon leopoldi" in FishBase. February 2017 version.
^Fishing World-records: Potamotrygon leopoldi. Retrieved 22 February 2017.
^"Polka-dot stingray, Potamotrygon leopoldi". Animals. Dallas World Aquarium. Retrieved 25 January 2016.
^ a b cCarvalho, Marcelo R. de (2016). "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". Zootaxa. 4167 (1): 1–63. doi:10.11646/zootaxa.4167.1.1. PMID 27701358.
^ a b cKirchhoff, Kim N.; Klingelhöfer, Ines; Dahse, Hans-Martin; Morlock, Gertrud; Wilke, Thomas (December 2014). "Maturity-related changes in venom toxicity of the freshwater stingray Potamotrygon leopoldi". Toxicon. 92: 97–101. doi:10.1016/j.toxicon.2014.10.011. PMID 25449099.
^Rutledge, Kelsi M.; Summers, Adam P.; Kolmann, Matthew A. (June 2019). "Killing them softly: Ontogeny of jaw mechanics and stiffness in mollusk‐feeding freshwater stingrays". Journal of Morphology. 280 (6): 796–808. doi:10.1002/jmor.20984. ISSN 0362-2525. PMID 30950541. S2CID 96436321.
Media related to Potamotrygon leopoldi at Wikimedia Commons