The Southern Acornshell (Epioblasma othcaloogensis) and Upland Combshell (Epioblasma metastriata) Declared Extinct

Written by Andrew Nagy

On September 30, 2021, the U.S. Fish and Wildlife Service removed 23 species from the Federal Lists of Endangered and Threatened Wildlife and Plants. They determined that these species are extinct, and consequently no longer need managed under the ESA. Eight of these species were mussels, two of which were historically found in Georgia waterways.

Both the Southern Acornshell (Epioblasma othcaloogensis) and the Upland Combshell (Epioblasma metastriata) are endemic to the Mobile River Basin and were historically present in the Upper Coosa River system in northeast Georgia. Impoundments and water quality degradation led to declines in both species.

Southern Acornshell (Epioblasma othcaloogensis). Photo by Jason Wisniewski (Georgia DNR – Wildlife Resources).

The last Southern Acornshell individuals were found in the Upper Coosa drainage in 1974 and the last Upland Combshell individual was found in the Conasauga River in 1988.  Despite intensive survey efforts since, scientists have failed to find live individuals or shells of either species.

Upland Combshell (Epioblasma metastriata). Photo by Jason Wisniewski (Georgia DNR – Wildlife Resources).

Mussels are important members of aquatic ecosystems. As filter feeders, they assist in nutrient cycling and can help remove harmful substances from the water. In addition, they stabilize the substrate and their shells provide habitat for algae and insects. Unfortunately, they are also among the most imperiled taxa on earth. Approximately 72 percent of mussel species have protection designation by the states in which they exist.

For the full report, see