The Nazas slider (''Trachemys hartwegi'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked tu ...

in the family

Emydidae Emydidae (Latin ''emys'' (freshwater tortoise) + Ancient Greek εἶδος (''eîdos'', “appearance, resemblance”)) is a family of testudines (turtles) that includes close to 50 species in 10 genera. Members of this family are commonly calle ...

. It is

endemic Endemism is the state of a species being found 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 found elsew ...

to northern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Taxonomy

It was formerly considered a subspecies of the

Big Bend slider The Big Bend slider (''Trachemys gaigeae''), also called the Mexican Plateau slider, is a species of aquatic turtle in the family Emydidae. The species is endemic to the Southwestern United States and northern Mexico. Taxonomy The species ''Tr ...

(''T. gaigeae''), but in 2021 it was reclassified as a distinct species by the

Turtle Taxonomy Working Group The Turtle Taxonomy Working Group (TTWG) is an informal working group of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group (TFTSG). It is composed of a number of leading turtle taxonomists, with varying participation by individual partici ...

and the

Reptile Database The Reptile Database is a scientific database that collects taxonomic information on all living reptile species (i.e. no fossil species such as dinosaurs). The database focuses on species (as opposed to higher ranks such as families) and has entrie ...

. Both ''hartwegi'' and ''gaigeae'' may have originally evolved in

endorheic basins An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...

until their respective basins were captured by the Pecos- Grande system.

Distribution

It is endemic to Mexico, where it is only found in the main channel of the

Nazas River The Nazas River is a river located in northern Mexico, in the states of Coahuila and Durango. It is part of the endorheic Bolsón de Mapimí. It is only long, but irrigates an area of in the middle of the desert. The Nazas is also nurtured by t ...

in northeastern

Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in ...

and southwestern

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

Status

Although presently considered conspecific with ''T. gaigeae'' on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

, with ''T. gaigeae'' as a whole classified as Vulnerable, ''T. hartwegi'' qualifies for

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

status due to widespread extirpation across its range. The population near

San Pedro de las Colonias San Pedro (formally: San Pedro de las Colonias) is a city located in the southwestern part of the state of Coahuila in Mexico. San Pedro lies east-northeast of the city of Torreón and serves as the seat of the surrounding municipality of the s ...

was thought to be nearing extinction as of 1990, and a population near Laguna Viesca in Coahuila is thought to have been extinct since 1960. Aridity and increased use of water for irrigation is thought to pose a risk to all populations of ''T. hartwegi'' aside from those near Presa El Palmito in Durango.

References

{{Taxonbar, from=Q9360658 Trachemys Turtles of North America Endemic reptiles of Mexico Mexican Plateau Reptiles described in 1990