''Theliderma sparsa'', the Appalachian monkey-face pearly mussel or Appalachian monkeyface, is a species of freshwater mussel, an 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 in the family Unionidae, the river mussels. This species is endemic to western Virginia and eastern Tennessee in the

Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, Ca ...

region, in the Southeastern United States. It is critically endangered due to pollution of the rivers in which it lives. Being a

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

, the mussel absorbs the pollutants which contaminate the river as it feeds.

Distribution

There are two to three populations remaining. In the Clinch River of Virginia there is a small, isolated population. A population in the upper Powell River in Tennessee is nearly gone. These occurrences may not be viable. All other occurrences have been extirpated.

Reproduction

Like other unionid mussels, ''Theliderma sparsa'' uses fish as an intermediate host for its glonchidia larvae. Captive breeding experiments have demonstrated that the mussel larvae can develop on the gills of

blotched chub The blotched chub (''Erimystax insignis'') is a species of fish in the family Cyprinidae, the minnow and carp family. This fish species in native to the Southeastern region of the United States. Appearance The blotched chub is a slender, silve ...

(''Erimystax insignis'') and

streamline chub The streamline chub (''Erimystax dissimilis'') is one of the 324 fish species found in Tennessee. Geographic distribution Found in the Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwe ...

(''Erimystax dissimilis''). Water temperature and vibration prompt release of glonchidia, according to Virginia Department of Wildlife Resources Southwest Virginia Mussel Recovery Coordinator Tim Lane.

References

Molluscs of the United States Ecology of the Appalachian Mountains Endemic fauna of Tennessee Endemic fauna of Virginia Critically endangered fauna of the United States sparsa Bivalves described in 1841 Taxonomy articles created by Polbot {{Unionidae-stub