Madagascan big-headed turtle

Photographed at Berenty Reserve
Conservation status
Critically Endangered (IUCN 3.1)^[1]
CITES Appendix II (CITES)^[2]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Testudines
Suborder:	Pleurodira
Family:	Podocnemididae
Genus:	Erymnochelys Baur, 1888
Species:	E. madagascariensis
Binomial name
*Erymnochelys madagascariensis* (Grandidier,1867)^[1]

The Madagascan big-headed turtle (Erymnochelys madagascariensis)^[1] is a turtle native to the waters of permanent slow moving rivers and lakes in western Madagascar. These turtles are critically endangered and have been evaluated to be the most endangered turtle in the world by a 2018 review.^[3] Due to its ancient origins and threatened status, it is ranked as #1 on the EDGE of Existence programme's list of priority reptiles.^[4]

Taxonomy

It is a highly evolutionary distinctive species, the only member of the ancient family Podocnemidae found outside of South America. It diverged from its closest relative, Podocnemis, during the Late Cretaceous, about 78 million years ago, possibly following the submergence of a land bridge connecting South America and Antarctica with Madagascar.^[5]

Despite Madagascar's long isolation and extensive number of endemic species, the Madagascan big-headed turtle is among the only terrestrial vertebrates whose isolation on Madagascar is thought to be due to Gondwanan vicariance during the Cretaceous; the only other extant Malagasy land vertebrates with this evolutionary history are two genera of blindsnakes (Madatyphlops and Xenotyphlops). All other Malagasy land vertebrates dispersed from the mainland to an already-isolated Madagascar from the latest Cretaceous to the present.^[6]

Description

The Madagascan big-headed turtle is one of the most endangered turtles in the world, and is also included in the Turtle Conservation Funds (TCF) top 25 endangered. It has a hard dark brown shell enclosing all the soft parts of the body and, as its name indicates, a very large head. Young turtles have a soft pattern of fine black lines on their shells, but they disappear with age.^[7]

Habitat

This species inhabits large areas with freshwater such as permanent slow streaming rivers, backwaters and lakes. Many of the hatching and juvenile turtles move into smaller rivers, where they can grow quickly and safely before going into deeper and larger bodies of water.

Range

It can be found in the western lowland areas of Madagascar.^[8]

Threats

The main threat for this species is that they are heavily exploited for food, caught in nets, fish traps and by hooks and lines. It is also hunted for illegal export to Asia for the traditional medicinal market. Another threat is land development as it destroys its natural habitat.

Despite their vulnerability to extinction, they are commonly eaten for food and they are still commonly shipped from Madagascar to Asia to help meet the demand of Asia's traditional medicine market. A captive breeding program has also been started to prevent the species from becoming extinct. The Turtle Conservation Fund (TCF) intends to raise US$5.6 million to cover a five-year 'Global Action Plan' which includes captive breeding and reintroduction projects, trade monitoring, new rescue centers, local conservation plans, and educational programs.

References

^ ^a ^b ^c Rhodin, Anders G.J.; van Dijk, Peter Paul; Inverson, John B.; Shaffer, H. Bradley (2010-12-14). "Turtles of the world, 2010 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status" (PDF). Chelonian Research Monographs. 5: 000.136. doi:10.3854/crm.5.000.checklist.v3.2010. ISBN 978-0965354097. Archived from the original (PDF) on 2011-07-17.
^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
^ Gumbs, Rikki; Gray, Claudia; Wearn, Oliver; Owen, Nisha (2018). "Tetrapods on the EDGE: Overcoming data limitations to identify phylogenetic conservation priorities" (PDF). PLOS ONE. 13 (4): e0194680. Bibcode:2018PLoSO..1394680G. doi:10.1371/journal.pone.0194680. PMC 5894989. PMID 29641585.
^ "Species". EDGE of Existence. Retrieved 2023-06-07.
^ Vargas-Ramírez, Mario; Castaño-Mora, Olga V.; Fritz, Uwe (2008-12-20). "Molecular phylogeny and divergence times of ancient South American and Malagasy river turtles (Testudines: Pleurodira: Podocnemididae)". Organisms Diversity & Evolution. 8 (5): 388–398. doi:10.1016/j.ode.2008.10.001. ISSN 1439-6092.
^ Ali, Jason R.; Hedges, S. Blair (2023-05-04). "The colonisation of Madagascar by land‐bound vertebrates". Biological Reviews. doi:10.1111/brv.12966. ISSN 1464-7931.
^ "Madagascar big-headed turtle videos, photos and facts - Erymnochelys madagascariensis". Arkive. Archived from the original on 2011-11-09. Retrieved 2012-08-20.
^ "Madagascar big-headed turtle videos, photos and facts - Erymnochelys madagascariensis". Arkive. Archived from the original on 2011-11-09. Retrieved 2012-08-20.

Side-necked turtle species

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

Acanthochelys

	Acanthochelys macrocephala Acanthochelys pallidipectoris Acanthochelys radiolata Acanthochelys spixii

Chelus

	Chelus fimbriata

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

Genus

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.

See also List of Testudines families

Taxon identifiers
Erymnochelys madagascariensis	Wikidata: Q862042 Wikispecies: Erymnochelys madagascariensis ADW: Erymnochelys ARKive: erymnochelys-madagascariensis BOLD: 171541 CoL: 6GQJ9 EoL: 794731 Fossilworks: 239573 GBIF: 2442800 iNaturalist: 40150 IRMNG: 10359217 ITIS: 551900 IUCN: 8070 NCBI: 44520 RD: madagascariensis Species+: 6722
Erymnochelys	Wikidata: Q14566149 Wikispecies: Erymnochelys BOLD: 171540 CoL: 62S43 EoL: 83815 Fossilworks: 239572 GBIF: 2442799 iNaturalist: 40149 IRMNG: 1198490 ITIS: 551739 NCBI: 44519