''Rotundaria couchiana'', the Rio Grande monkeyface, 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 ...

of freshwater mussel. It is native to Chihuahua, Mexico and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

and

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

in the United States. This species experienced a tremendous decline due to

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

in the 1800s. The last confirmed living individual was seen near Brackettville, Texas in 1898. This species is likely extinct, although there is the slim possibility that it could persist in poorly surveyed regions on the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

drainage.NatureServe
/ref> It was formerly classified under ''

Quadrula ''Quadrula'' is a genus of freshwater mussels, aquatic bivalve mollusks in the family Unionidae native to rivers of the American Midwest and mid-south. All have thick nacreous shells with well-developed hinge teeth, many also with external she ...

'', but in 2012 it was moved to ''Rotundaria'' based on genetic evidence.

References

Critically endangered fauna of the United States couchiana Bivalves described in 1860 Taxonomy articles created by Polbot {{Unionidae-stub