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
[edit]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
[edit]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
[edit]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
[edit]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
[edit]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
[edit]- ^ 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
[edit]- 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.