Chelus orinocensis

Chelus orinocensis, the Orinoco mata mata, is a species of freshwater turtle found in northern South America in the Orinoco, upper Rio Negro–Branco and Essequibo basins, and in Trinidad.^[1] It was split off from the very similar Chelus fimbriata in 2020.^[2]

Chelus orinocensis
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Testudines
Suborder:	Pleurodira
Family:	Chelidae
Genus:	Chelus
Species:	C. orinocensis
Binomial name
Chelus orinocensis Vargas-Ramírez, et al. 2020[2]

Taxonomy

A genetic analysis of the mata mata was reported in 2020, which showed a deep split between two of its populations. The authors proposed that the mostly Orinoco population be assigned to a new species, Chelus orinocensis, with the Amazon population retaining the Chelus fimbriatus species designation. However, Chelus fimbriatus is absent from the upper Rio Negro–Branco system (the northernmost part of the Amazon basin), which instead is inhabited by Chelus orinocensis.^[2]

Prior to its description as a separate species, observations of distinctive morphological differences had already been noted among specimens in the populations of the Amazon and Orinoco basins.^[3]

References

1. Rhodin, Anders G.J.; Inverson, John B.; Roger, Bour; Fritz, Uwe; Georges, Arthur; Shaffer, H. Bradley; van Dijk, Peter Paul; et al. (Turtle Taxonomy Working Group) (2021). Rhodin A. G.J.; Iverson J.B.; van Dijk P.P.; Saumure R.A.; Buhlmann K.A.; Pritchard P.C.H.; Mittermeier R.A. (eds.). "Turtles of the world, 2021 update: Annotated checklist and atlas of taxonomy, synonymy, distribution, and conservation status (9th Ed.)". Chelonian Research Monographs. Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. 9 (8 ed.): 1–472. doi:10.3854/crm.8.checklist.atlas.v9.2021. ISBN 978-1-5323-5026-9.
2. Vargas-Ramírez, M.; Caballero, S.; Morales-Betancourt, M.A.; Lasso, C.A.; Amaya, L.; Gregorio Martínez, J.; das Neves Silva Viana, M.; Vogt, R.C.; Pires Farias, I.; Hrbek, T.; Campbell, P.D.; Fritz, U. (2020). "Genomic analyses reveal two species of the matamata (Testudines: Chelidae: Chelus spp.) and clarify their phylogeography". Molecular Phylogenetics and Evolution. 148: 106823. Bibcode:2020MolPE.14806823V. doi:10.1016/j.ympev.2020.106823. PMID 32278863.
3. Sanchez-Vilaga, Marcelo R.; Prichard, Peter C. H.; Paolillo, Alfredo; Linares, Omar J. (January 1995). "Geographic variation in the matamata turtle, Chelus fimbriatus, with observations on its shell morphology and morphometry" (PDF). Chelonian Conservation and Biology. 1: 292–300.