Didacna pyramidata
| Didacna pyramidata | |
|---|---|
| Illustrations of Cardium pyramidatum from Oscar Grimm's publication (1877) | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Order: | Cardiida |
| Family: | Cardiidae |
| Genus: | Didacna |
| Species: | D. pyramidata
|
| Binomial name | |
| Didacna pyramidata (Grimm, 1877)
| |
Didacna pyramidata is a brackish-water bivalve mollusc of the family Cardiidae, the cockles. It has a high rounded-triangular, rather thick, cream shell, up to 30–45 mm (1.2–1.8 in) in length, with flattened ribs. The species is endemic to the Caspian Sea. It lives in the Southern Caspian sub-basin and in the southern part of the Middle Caspian sub-basin at depths between 30 and 100 m (98–328 ft), rarely down to 130 m (430 ft).
Description
Didacna pyramidata has a high rounded-triangular, rather thick, convex shell, with about 28–38 flattened radial ribs and a distinct posterior ridge which is sometimes marked by a stronger developed rib.[1][2][3] The shell length is up to 30–45 mm (1.2–1.8 in). The external coloration is cream, with thin brownish periostracum. The interior is whitish, with a yellow-brown stain on the posterior margin.[3]
Differences from similar species
Didacna trigonoides has a more inflated shell, with a stronger protruding umbo, less ribs and a weaker posterior lateral tooth in the right valve.[3][4]
The fossil species Didacna subpyramidata has fewer ribs, a less distinct posterior ridge, higher umbo and its shell is usually more convex.[3][4]
Didacna praetrigonoides is a possibly extinct species mostly known from the Late Pleistocene deposits of the Caspian Sea, although its shells sometimes wash up on beaches.[5] It differs from D. pyramidata by a more elongated and convex shell, with a more protruding umbo.[4]
Distribution and ecology
Didacna pyramidata is endemic to the Caspian Sea.[6] It lives in the Southern Caspian sub-basin and in the southern part of the Middle Caspian sub-basin at depths between 30 and 100 m (98–328 ft), rarely down to 130 m (430 ft).[1] It does not occur in waters with salinity of less than 10–12‰.[7]
Fossil record
Didacna pyramidata occurs in the Holocene (Neocaspian) deposits of the middle and southern parts of the Caspian Sea. Nevesskaja (2007) hypothesized that it descended from the Late Pleistocene D. praetrigonoides.[4]
Taxonomy
The species was first described as Cardium pyramidatum by Oscar Andreevich Grimm in 1877 from live individuals which were found in the southern part of the Caspian Sea off Azerbaijan[5] at depths of 42–130 m (140–430 ft).[8] These specimens are now stored in the Zoological Institute of the Russian Academy of Sciences and the one collected at a depth of 64 m (210 ft)[3] has been designated as the lectotype of D. pyramidata by Logvinenko and Starobogatov (1967). The coordinates of the type locality are 39°47'N 49°59'30"E.[9][10]
References
- ^ a b Logvinenko, B. M.; Starobogatov, Y. I. (1969). "Tip Mollyuski. Mollusca" [Phylum Molluscs. Mollusca]. In Birshteyn, Y. A.; Vinogradov, L. G.; Kondakov, N. N.; Kuhn, M. S.; Astakhova, T. V.; Romanova, N. N. (eds.). Atlas bespozvonochnykh Kaspiyskogo morya [Atlas of the Invertebrates of the Caspian Sea] (in Russian). Moscow: Pishchevaya Promyshlennost. p. 324.
- ^ Kijashko 2013, pp. 346–347.
- ^ a b c d e ter Poorten, J. J. (2024). A taxonomic iconography of living Cardiidae. Harxheim: ConchBooks. p. 156. ISBN 978-3-948603-48-9.
- ^ a b c d Nevesskaja, L. A. (2007). "History of the genus Didacna (Bivalvia: Cardiidae)". Paleontological Journal. 41 (9): 861–949. Bibcode:2007PalJ...41..861N. doi:10.1134/s0031030107090018.
- ^ a b Wesselingh, F. P.; Neubauer, T. A.; Anistratenko, V. V.; Vinarski, M.; Yanina, T.; ter Poorten, J. J.; Kijashko, P.; Albrecht, C.; Anistratenko, O. Y.; D'Hont, A.; Frolov, P.; Gándara, A. M.; Gittenberger, A.; Gogaladze, A.; Karpinsky, M.; Lattuada, M.; Popa, L.; Sands, A. F.; van de Velde, S.; Vandendorpe, J.; Wilke, T. (2019). "Mollusc species from the Pontocaspian region – an expert opinion list". ZooKeys (827): 31–124. Bibcode:2019ZooK..827...31W. doi:10.3897/zookeys.827.31365. PMC 6472301. PMID 31114425.
- ^ Kijashko 2013, p. 358.
- ^ Zhadin, V. I. (1952). Mollyuski presnykh i solonovatykh vod SSSR [Molluscs of Fresh and Brackish Waters of the USSR] (PDF). Opredeliteli po faune SSSR, izdavayemyye Zoologicheskim institutom AN (in Russian). Vol. 46. Moscow–Leningrad: The USSR Academy of Sciences Press. p. 347. Archived (PDF) from the original on 2 December 2024.
- ^ Grimm, O. A. (1877). Kaspijskoe more i ego fauna [The Caspian Sea and its Fauna]. Trudy Aralo-Kaspiiskoi Ekspeditsii (in Russian). Vol. 2 (2). St. Petersburg: St. Petersburg Society of Naturalists. pp. 46–49.
- ^ Logvinenko, B. M.; Starobogatov, Y. I. (1967). "K izucheniyu vidovogo sostava fauny dvustvorchatykh mollyuskov tanatotsenozov podvodnogo sklona Azerbaydzhanskogo poberezh'ya Kaspiya" [On the study of species composition of the fauna of bivalves in tanatocoenoses of underwater slope of Azerbaijan coast of the Caspian Sea.]. In Kudritsky, D. M. (ed.). Opyt geologo-geomorfologicheskikh i gidrobiologicheskikh issledovaniy beregovoy zony morya [An experience of geologo-geomorphological and hydrobiological studies of coastal zone of the sea] (in Russian). Leningrad: Nauka. pp. 225–235.
- ^ Kijashko 2013, p. 357.
Cited texts
- Kijashko, P. V. (2013). "Mollyuski Kaspiyskogo morya" [Molluscs of the Caspian sea]. In Bogutskaya, N. G.; Kijashko, P. V.; Naseka, A. M.; Orlova, M. I. (eds.). Identification keys for fish and invertebrates of the Caspian Sea (in Russian). Vol. 1. Fish and molluscs. St. Petersburg; Moscow: KMK Scientific Press Ltd. pp. 298–392. ISBN 978-5-87317-932-9.