''Medionidus parvulus'', the Coosa moccasinshell, is a rare

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

freshwater mussel Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves. The majority of species of bivalve molluscs ...

in the family

Unionidae The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is at its most dive ...

, 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, biv ...

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 es ...

is native to

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to t ...

and

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 ...

in the United States, and has been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from the state of

Alabama (We dare defend our rights) , anthem = " Alabama" , image_map = Alabama in United States.svg , seat = Montgomery , LargestCity = Huntsville , LargestCounty = Baldwin County , LargestMetro = Greater Birmingham , area_total_km2 = 135,7 ...

.''Medionidus parvulus''.
The Nature Conservancy. It is a federally listed endangered species of the United States.USFWS
Endangered status for eight freshwater mussels and threatened status for three freshwater mussels in the Mobile River Drainage.
''Federal Register'' March 17, 1993. This mussel is up to 4 centimeters long or occasionally larger and has a thin, fragile, dark brown or yellow-brown shell. The nacre of the shell is blue, sometimes with pink areas. This mussel is native to the

Mobile River The Mobile River is located in southern Alabama in the United States. Formed out of the confluence of the Tombigbee and Alabama rivers, the approximately river drains an area of of Alabama, with a watershed extending into Mississippi, Georgia ...

drainage, where it was once sporadic but widespread. This species is rare except in

Polk County, Tennessee Polk County is a county located in the southeastern corner of the U.S. state of Tennessee. As of the 2020 United States census, its population was 17,544. Its county seat is Benton. The county was created on November 28, 1839, from parts of B ...

, where it is locally common in the

Conasauga River The Conasauga River is a river that runs through southeast Tennessee and northwest Georgia. The Conasauga River is longU.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 27, 2011 an ...

. It can also be found in the tributary Holly Creek, which extends into Georgia. It is in severe decline, having been extirpated from much of the

Coosa River The Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 27, 2011 ...

system and all of the waterways in Alabama where it once occurred.

References

Natural history of Tennessee Natural history of Georgia (U.S. state) parvulus Bivalves described in 1860 ESA endangered species Taxonomy articles created by Polbot {{Unionidae-stub