''Corbicula fluminalis'' is a

species In biology, a species is the basic unit of 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 the appropriate s ...

of freshwater

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...

, 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 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 e ...

in the family Cyrenidae. This species is distinct from, but often confused with, the rather similar species ''

Corbicula fluminea ''Corbicula fluminea'' is a species of freshwater clam native to eastern Asia which has become a successful invasive species throughout North America, South America, and Europe. ''Corbicula fluminea'' is commonly known in the west as the Asian cl ...

''. Even though both species are native to Asia, they are both present as

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

in the United States and Europe, and they are both commonly known as "Asian clams".

Discriminating the two species

Two species are present in introduced populations, ''C. fluminea'' and ''C. fluminalis''.It is not entirely clear that this is the correct name (Jueg & Zettler, 2004) However, the two species are often confused. The scientific names themselves are also sometimes confused in the literature (e.g. by being called "Corbicula fluminata"). Care needs to be taken in order to properly distinguish the two species. The ratio of width and height in ''C. fluminea'' is on average 1.1. In ''C. fluminalis'' it is smaller (0.97); still, there is much variation and considerable overlap in shape. Most easily, the two species can be distinguished by the density of the ribs on the shell; ''C. fluminea'' has 7 to 14 ribs per cm, ''C. fluminalis'' 13 to 28. (2004): Die Molluskenfauna der Elbe in Mecklenburg-Vorpommern mit Erstnachweis der Grobgerippten Körbchenmuschel ''Corbicula fluminea'' (O. F. Müller 1756). ''Mitteilungen der NGM'' 4(1): 85-89
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This character is already clearly recognizable (albeit only by direct comparison) in very small (5 mm diameter) specimens. In addition, when viewed from the side (looking at the opening between the shells), ''C. fluminalis'' is rounder, almost heart-shaped, while ''C. fluminea'' has a slightly flatter shape, like a teardrop with a notched broad end. Small specimens of ''C. fluminalis'' are almost spherical, while those of ''C. fluminea'' are decidedly flattened. All these differences except the rib number are a consequence of ''C. fluminalis'' having a markedly more swollen, pointed and protruding umbo.

References

{{DEFAULTSORT:Corbicula Fluminalis Cyrenidae Molluscs described in 1774 Taxa named by Otto Friedrich Müller

Discriminating the two species

See also

References