''Mercenaria'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of edible marine

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 ...

s in the family

Veneridae The Veneridae or venerids, common name: Venus (mythology), Venus clams, are a very large family of minute to large, saltwater clams, marine bivalve molluscs. Over 500 living species of venerid bivalves are known, most of which are edible, and m ...

, the Venus clams. The genus includes the quahogs, consisting of ''Mercenaria mercenaria'', the northern quahog or

hard clam The hard clam (''Mercenaria mercenaria''), also known as the round clam, hard-shell (or hard-shelled) clam, or the quahog, is an edible marine bivalve mollusk that is native to the eastern shores of North America and Central America from Prince ...

, and ''M. campechiensis'', the southern quahog, both important species for human consumption.

Species

The

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

accepts the following extant species as valid: * '' Mercenaria browni'' Petuch & Berschauer, 2019 * '' Mercenaria campechiensis'' (Gmelin, 1791) – Southern quahog * '' Mercenaria hartae'' Petuch, 2013 * '' Mercenaria mercenaria'' (Linnaeus, 1758) – Northern quahog * '' Mercenaria stimpsoni'' (Gould, 1861) – Stimpson's hard clam * '' Mercenaria texana'' (Dall, 1902) ''Mercenaria mercenaria'' and ''M. campechiensis'' can hybridise where their ranges overlap.

Fossils species

Several other species are known only from fossils. These mollusk are known since the

Upper Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

(28.1–23.03 Ma). Fossil shells have been found in the sediments of

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, and

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. At least the following species or subspecies are known from fossils: Tellus Mercenaria

*''† Mercenaria blakei'' Ward 1992 *'' Mercenaria campechiensis'' Gmelin, 1791 **''†Mercenaria campechiensis carolinensis'' Conrad 1875 **''†Mercenaria campechiensis rileyi'' Conrad 1838 **''†Mercenaria campechiensis tridacnoides'' Lamarck 1818 * ''† Mercenaria capax'' Conrad 1843 * ''† Mercenaria cuneata'' Conrad 1869 * ''† Mercenaria druidi'' Ward 1992 * ''† Mercenaria ducatelli'' Conrad 1838 * ''† Mercenaria erecta'' Kellum 1926 * ''† Mercenaria gardnerae'' Kellum 1926 * ''† Mercenaria langdoni'' Dall 1900 * '' Mercenaria mercenaria'' (Linnaeus, 1758) **''†Mercenaria mercenaria notata'' Say 1822 * ''† Mercenaria nannodes'' Gardner 1947 * ''† Mercenaria permagna'' Conrad 1838 * ''† Mercenaria plena'' Conrad 1869 **''†Mercenaria plena inflata'' Dall 1903 **''†Mercenaria plena nucea'' Dall 1903 * ''† Mercenaria problematica'' (K. Martin, 1883) * ''† Mercenaria prodroma'' Gardner 1947 * ''† Mercenaria tetrica'' Conrad 1838 * ''† Mercenaria yokoyamai'' (Makiyama, 1927) * ''† Mercenaria violacea'' Schumacher 1817 The World Register of Marine Species lists ''Mercenaria cuneata'' and ''M. violacea'' as synonyms of extant species.

Pearls

The northern quahog clam is known for producing very rare and collectible, non-nacreous pearls known for their purple color. Quahog pearls are often button-shaped, and can range in color from white to lavender, to purple.

Species

Fossils species

Pearls

References

Further reading