Didacna parallella
From Wikipedia, the free encyclopedia
| Didacna parallella | |
|---|---|
 | |
| Shell from the Late Pleistocene deposits of the Caspian Sea (Dagestan, Russia)[1] | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Order: | Cardiida |
| Family: | Cardiidae |
| Genus: | Didacna |
| Species: | D. parallella |
| Binomial name | |
| Didacna parallella Bogachev, 1932 | |
| Synonyms | |
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Didacna parallella is a brackish-water bivalve mollusc of the family Cardiidae, the cockles. It has an oval, rounded-trapezoidal or trapezoidal, thin, cream or tan shell, up to 30–55 mm (1.2–2.2 in) in length, with an off-centered umbo and flattened ribs. The species is endemic to the Caspian Sea. It lives in the Southern Caspian and along the western coast of the Middle Caspian at depths between 50 and 85 m (164–279 ft).
Didacna parallella has an oval, rounded-trapezoidal or trapezoidal, thin, moderately convex shell, with an anteriorly displaced umbo, 29–42 flattened radial ribs and a posterior ridge, which is marked by a thickened rib.[2][3][4][5] The shell length is up to 30–55 mm (1.2–2.2 in).[4][5] The external coloration is cream or tan. The interior is cream, with a reddish brown stain on the posterior margin.[5] The hinge consists of two cardinal teeth in the right valve and one cardinal tooth in the left valve.[4][6]
Distribution and ecology
Didacna parallella is endemic to the Caspian Sea. It lives in the Southern Caspian and along the western coast of the Middle Caspian at depths between 50 and 85 m (164–279 ft).[7][8] Records from depths of 200–300 m (660–980 ft) in the southern Caspian Sea off Azerbaijan are uncertain.[9]
J. J. ter Poorten (2024) noted that D. parallella could be extinct due to the lack of recent records of living specimens.[5] F. P. Wesselingh and co-authors (2019) have stated that live records are known at least until 1986 and the species is unlikely to be extinct.[9]
Fossil record
Didacna parallella occurs in the Late Pleistocene (Hyrcanian and Khvalynian)[1] and Holocene (Neocaspian) deposits of the Caspian Sea.[10]