''Theliderma intermedia'', the Cumberland monkeyface pearly mussel or Cumberland 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 in the family Unionidae, the river mussels. This aquatic

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

is native to

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

and

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

in the United States. Historically widespread in the upper

Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names, ...

system, it populations have been reduced by

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 ...

and pollution. It now only occurs in two tributaries: the

Duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...

and Powell Rivers.''Quadrula intermedia''.
The Nature Conservancy.USFWS
''Quadrula intermedia'' Five-year Review.
July 2011. It is a federally listed

endangered species 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 inv ...

. This species is yellow-green or greenish yellow in color. It can reach at least 35 years old. Like other mussels, it has larvae called glochidia that lodge in the gills of fish to develop into juvenile mussels. Hosts for this species include the streamlined chub (''Erymystax dissimilis'') and blotched chub (''Erymystax insignis''). This mussel has been extirpated from the Elk River. There is still a population in the Powell River, and the population in the Duck River appears to be viable.

References

Natural history of Tennessee Natural history of Virginia intermedia Bivalves described in 1836 Taxonomy articles created by Polbot {{Unionidae-stub