Theliderma sparsa

Theliderma sparsa, the Appalachian Rockshell pearly mussel or Appalachian rockshell, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.
This species is endemic to western Virginia and eastern Tennessee in the Appalachia region, in the Southeastern United States.
It is critically endangered due to pollution of the rivers in which it lives. Being a detritivore, 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 glochidia. Captive breeding experiments have demonstrated that the mussel larvae can develop on the gills of blotched chub and streamline chub. Water temperature and vibration prompt release of glochidia, according to Virginia Department of Wildlife Resources Southwest Virginia Mussel Recovery Coordinator Tim Lane.

Conservation

Theliderma sparsa is a federally endangered species. It gained protection under the Endangered Species Act with this status in 1976.