Chelus orinocensis

Species of turtle

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]

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]

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

^ ^a ^b 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.
^ ^a ^b ^c 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. doi:10.1016/j.ympev.2020.106823. PMID 32278863.
^ 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.

Side-necked turtle species

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Subclass: Anapsida
Order: Testudines
Suborder: Pleurodira

Family

Acanthochelys

	Acanthochelys macrocephala Acanthochelys pallidipectoris Acanthochelys radiolata Acanthochelys spixii

Chelus

	Chelus fimbriata Chelus orinocensis †Chelus colombiana

Mesoclemmys

	Mesoclemmys dahli Mesoclemmys gibba Mesoclemmys jurutiensis Mesoclemmys nasuta Mesoclemmys perplexa Mesoclemmys raniceps Mesoclemmys sabiniparaensis Mesoclemmys tuberculata Mesoclemmys vanderhaegei †Mesoclemmys vanegasorum Mesoclemmys zuliae

Phrynops

	Phrynops geoffroanus Phrynops hilarii †Phrynops paranaensis Phrynops tuberosus Phrynops williamsi

Platemys

	Platemys platycephala

Ranacephala

	Ranacephala hogei

Rhinemys

	Rhinemys rufipes

Chelodininae

Chelodina

Chelodina	Chelodina canni Chelodina gunaleni Chelodina longicollis Chelodina mccordi †Chelodina murrayi Chelodina novaeguineae Chelodina pritchardi Chelodina reimanni Chelodina steindachneri
Chelydera	†Chelodina alanrixi Chelodina burrungandjii Chelodina expansa Chelodina insculpta Chelodina kuchlingi Chelodina kurrichalpongo Chelodina parkeri Chelodina rugosa Chelodina walloyarrina
Macrochelodina	Chelodina oblonga

Elseya

Elseya	Elseya dentata Elseya branderhorsti Elseya flaviventralis
Pelocomastes	Elseya albagula Elseya irwini Elseya lavarackorum †Elseya nadibajagu †Elseya uberrima
Hanwarachelys	Elseya caelatus Elseya novaeguineae Elseya orestiad Elseya rhodini Elseya schultzei

Elusor

	Elusor macrurus

Emydura

	Emydura australis Emydura gunaleni Emydura macquarii Emydura subglobosa Emydura tanybaraga Emydura victoriae

Myuchelys

	Myuchelys belli Myuchelys georgesi Myuchelys latisternum Myuchelys purvisi

Rheodytes

	Rheodytes leukops †Rheodytes devisi

Hydromedusinae

Hydromedusa

	Hydromedusa maximiliani Hydromedusa tectifera

Pseudemydurinae

Pseudemydura

	Pseudemydura umbrina

Pelomedusidae

Pelomedusa

	Pelomedusa subrufa

Pelusios

	Pelusios adansonii Pelusios bechuanicus Pelusios broadleyi Pelusios carinatus Pelusios castaneus Pelusios castanoides Pelusios chapini Pelusios cupulatta Pelusios gabonensis Pelusios marani Pelusios nanus Pelusios niger Pelusios rhodesianus Pelusios sinuatus Pelusios subniger Pelusios upembae Pelusios williamsi

Podocnemididae

Erymnochelys

	Erymnochelys madagascariensis

Peltocephalus

	Peltocephalus dumerilianus

Podocnemis

	Podocnemis erythrocephala Podocnemis expansa Podocnemis lewyana Podocnemis sextuberculata Podocnemis unifilis Podocnemis vogli

Phylogenetic arrangement of turtles based on Turtles of the World 2021 Update: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status. Key: †=extinct.

Testudines

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Diapsida
Order: Testudines

Suborder

Superfamily

Family

Genus

Cryptodira

Chelonioidea
(Sea turtles)

Cheloniidae	†Allopleuron Caretta †Carolinochelys Chelonia †Eochelone Eretmochelys †Gigantatypus †Glarichelys †Itilochelys Lepidochelys †Mexichelys †Miocaretta Natator †Pacifichelys †Syllomus †Tasbacka
Dermochelyidae	†Arabemys †Corsochelys †Cosmochelys Dermochelys †Eosphargis †Mesodermochelys †Psephophorus
	†Euclastes †Peritresius †Procolpochelys †Protosphargis †Puppigerus

Kinosternoidea

Dermatemydidae	Dermatemys
Kinosternidae	Claudius †Hoplochelys Kinosternon Staurotypus Sternotherus

Testudinoidea

Emydidae	†Acherontemys Chrysemys Clemmys Deirochelys Emys Actinemys Emydoidea Glyptemys Graptemys Malaclemys Pseudemys Terrapene Trachemys †Wilburemys
Geoemydidae	Batagur †Banhxeochelys Cuora Cyclemys Geoclemys Geoemyda Hardella Heosemys Leucocephalon Malayemys Mauremys Melanochelys Morenia Notochelys Orlitia Pangshura Rhinoclemmys Sacalia Siebenrockiella Vijayachelys
Platysternidae	Platysternon
Testudinidae	Aldabrachelys Astrochelys Centrochelys Chelonoidis Chersina Cylindraspis †Cymatholcus †Floridemys Geochelone Gopherus †Hadrianus †Hesperotestudo Homopus Indotestudo Kinixys Malacochersus Manouria †Megalochelys †Oligopherus Psammobates Pyxis †Solitudo Stigmochelys †Stylemys Testudo

Trionychia

Carettochelyidae	†Allaeochelys †Anosteira Carettochelys
Trionychidae	Amyda Apalone †Axestemys Chitra Cyclanorbis Cycloderma †Drazinderetes Dogania †Gilmoremys †Hutchemys †Khunnuchelys Lissemys Nilssonia Palea †Palaeoamyda Pelochelys Pelodiscus Rafetus Trionyx
	†Basilochelys †Sinaspideretes

Chelydridae	Chelydra †Chelydrops †Chelydropsis †Emarginachelys †Macrocephalochelys Macrochelys †Planiplastron †Protochelydra
†Nanhsiungchelyidae	†Anomalochelys †Basilemys †Jiangxichelys
†Protostegidae	†Alienochelys †Archelon †Atlantochelys †Bouliachelys †Calcarichelys †Cratochelone †Desmatochelys †Iserosaurus †Notochelone †Ocepechelon †Pneumatoarthrus †Protostega †Rhinochelys †Santanachelys †Terlinguachelys
	†Adocus †Argillochelys †Bashuchelys †Ctenochelys †Prionochelys †Toxochelys

Pleurodira

†Araripemydidae	†Araripemys
†Bothremydidae	†Araiochelys †Arenila †Azabbaremys †Bothremys †Cearachelys †Chedighaii †Chupacabrachelys †Eotaphrosphys †Foxemys †Galianemys †Ilatardia †Inaechelys †Itapecuruemys †Jainemys †Kinkonychelys †Kurmademys †Labrostochelys †Nigeremys †Phosphatochelys †Polysternon †Puentemys †Rosasia †Rhothonemys †Sankuchemys †Taphrosphys †Ummulisani †Zolhafah
Chelidae	Acanthochelys Chelodina Chelus Elseya Elusor Emydura Hydromedusa †Lomalatachelys Mesoclemmys Myuchelys Phrynops Platemys †Prochelidella Pseudemydura Rheodytes Rhinemys †Yaminuechelys
Pelomedusidae	Pelomedusa Pelusios
Podocnemididae	†Albertwoodemys †Bauruemys †Brontochelys †Caninemys †Carbonemys †Cerrejonemys †Cordichelys Erymnochelys †Lapparentemys †Latentemys Peltocephalus Podocnemis †Stupendemys
†Sahonachelyidae	†Sahonachelys †Sokatra

	†Caribemys †Caririemys †Tacuarembemys

Phylogenetic arrangement of turtles based on Turtles of the World 2017 Update: Annotated Checklist and Atlas of Taxonomy, Synonymy, Distribution, and Conservation Status. † = extinct.