The forkshell or Lewis pearly mussel,

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''Epioblasma lewisii'', was a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

freshwater mussel Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails. The majority of bivalve molluscs are saltwater species that l ...

, an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Unionidae The Unionidae are a Family (biology), 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 a ...

, the river mussels. This species was

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the drainages of the

Cumberland River The Cumberland River is a major waterway of the Southern United States. The U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed June 8, 2011 river drains almost of southern Kentucky and ...

and the

Tennessee River The Tennessee River is a long river located in the Southern United States, southeastern United States in the Tennessee Valley. Flowing through the states of Tennessee, Alabama, Mississippi, and Kentucky, it begins at the confluence of Fren ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, with one specimen reported from the

Ohio River The Ohio River () is a river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its river mouth, mouth on the Mississippi Riv ...

near

Cincinnati Cincinnati ( ; colloquially nicknamed Cincy) is a city in Hamilton County, Ohio, United States, and its county seat. Settled in 1788, the city is located on the northern side of the confluence of the Licking River (Kentucky), Licking and Ohio Ri ...

, Ohio. Its natural

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

was shallow riffle-beds of large rivers. This habitat was largely destroyed by dam construction and

canalization River engineering is a discipline of civil engineering which studies human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit. People have intervened in the natural course and b ...

, and the last populations of this species died sometime during the middle of the 20th century. Only a single museum specimen was collected that preserved the internal soft tissues. It appears to be closely related to ''

Epioblasma flexuosa ''Epioblasma flexuosa'', the arcuate pearly mussel or leafshell, was a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. This species was endemic to the United States, where it was found in the m ...

'', which is also now extinct.

References

Epioblasma Molluscs described in 1910 Taxa named by Edmund Murton Walker Taxonomy articles created by Polbot {{Unionidae-stub