''Atrina'' is a cosmopolitan

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 ...

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 ...

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

s belonging to the family

Pinnidae The pinnidae are a taxonomic family of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order Pteriida. Shell description The shells of bivalves in this family are fragile and have a long and triang ...

. A typical species is '' A. fragilis'', found in British waters. '' A. rigida'' ( Lightfoot, 1786) is found on the southeast coast of North America and in the West Indies. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''A. nigra'' ( Dillwyn, 1817, originally ''P. nigra''). ''Atrina'' is considered to represent the more primitive form within the Pinnidae; however, both genera '' Pinna'' and ''Atrina'' are very ancient. The genus ''Atrina'' is represented within the fossil record from the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

period to the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

period (age range: 242.0 to 0.0 million years ago). These fossils have been found all over the world.

Description

Molluscs within this genus are characterized by elongated, wedge-shaped shells, distinguished from the genus '' Pinna'' by the lack of any grooves in the

nacre Nacre ( , ), also known as mother-of-pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

ous lining of the shell, and by the central positioning of the adductor scar. As with other pen shells (

) they commonly stand point-first in the sea bottom in which they live, anchored by net of

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells ( Pinnidae), true mussels (Mytili ...

threads.

Species

Species within the genus ''Atrina'' include:Fossilworks
/ref> * '' Atrina affinis '' Sowerby, 1821† * '' Atrina argentea'' Conrad, 1848† * '' Atrina assimilis'' (Reeve, 1858) * '' Atrina chautardi'' (Nicklès, 1953) * '' Atrina chinensis'' (Deshayes, 1841) * '' Atrina cumingii'' (Reeve, 1858) * '' Atrina exusta'' (Gmelin, 1791) * ''

Atrina fragilis ''Atrina fragilis'', the fan mussel, is a species of large saltwater clam, a marine bivalve mollusc in the family Pinnidae, the pen shells. The fan mussel, ''Atrina fragilis'' is one of the largest (30 to 48 cm long) and rarest bivalve mollusc ...

'' ( Pennant, 1777) — fan mussel * '' Atrina harrisii'' Dall, 1898† * '' Atrina hystrix'' (Hanley, 1858) * '' Atrina inflata'' (Dillwyn, 1817) * '' Atrina jacksoniana'' Dall, 1898† * '' Atrina japonica'' (Reeve, 1858) * '' Atrina kinoshitai'' Habe, 1953 * '' Atrina lischkeana'' (Clessin, 1891) * '' Atrina magellanica'' Ihering, 1907† * '' Atrina marquesana'' P. W. Schultz & M. Huber, 2013 * '' Atrina maura'' (G. B. Sowerby I, 1835) * '' Atrina nigra'' (Dillwyn, 1817) * '' Atrina oldroydii'' Dall, 1901 * ''

Atrina pectinata ''Atrina pectinata'' is a species of bivalves belonging to the family Pinnidae. The species is found in the Old World. They are important in commercial fishing in Asia. They have the common name of ''kijogae'' 'pen shells'' ''A. pectinata'' is ...

'' (Linnaeus, 1767) * '' Atrina penna'' (Reeve, 1858) * '' Atrina pini'' P. W. Schultz & M. Huber, 2013 * '' Atrina piscatoria'' Glenn, 1904† * '' Atrina recta'' Dall, Bartsch & Rehder, 1938 * ''

Atrina rigida ''Atrina rigida'', commonly called the rigid pen shell, is a species of bivalve mollusc in the family (biology), family Pinnidae. Description The rigid shell has a pair of thick spiny valves held together by ligaments that run along the entire ...

'' ( Lightfoot, 1786) — stiff pen shell * '' Atrina rosenkrantzi'' Schnetler & M. S. Nielsen, 2018 † * '' Atrina seminuda'' (

Lamarck Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...

, 1819) — half-naked pen shell * '' Atrina serra'' (Reeve, 1858) * '' Atrina serrata'' (Sowerby, 1825) — saw-toothed pen shell * '' Atrina squamifera'' (Sowerby, 1835) * '' Atrina stephensi'' Hanna, 1926† * '' Atrina strangei'' (Reeve, 1858) * '' Atrina talarensis'' Olsson, 1928† * '' Atrina tasmanica'' (Tenison Woods, 1876) * '' Atrina teramachii'' Habe, 1953 * '' Atrina texta'' Hertlein, Hanna & A. M. Strong, 1943 * '' Atrina tuberculosa'' (G. B. Sowerby I, 1835) * '' Atrina vexillum'' (

Born Born may refer to: * Childbirth * Born (surname), a surname (see also for a list of people with the name) * ''Born'' (comics), a comic book limited series Places * Born, Belgium, a village in the German-speaking Community of Belgium * Born, Luxe ...

, 1778) — flag pen shell * '' Atrina zelandica'' (Gray in Yate, 1835) — the horse mussel

References

* * *

External links

idscaro.net
— images Pinnidae Bivalve genera Taxa named by John Edward Gray {{bivalve-stub