Finely ribbed shell clams

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Finely ribbed shell clams
Finely ribbed mussel mussel (Corbicula fluminalis)

Finely ribbed mussel mussel ( Corbicula fluminalis )

Systematics
Order : Veneroid
Superfamily : Sphaerioidea
Family : Cupcake clams (Corbiculidae)
Subfamily : Corbiculinae
Genre : Cupcake clams ( corbicula )
Type : Finely ribbed shell clams
Scientific name
Corbicula fluminalis
( OV Müller , 1774)

The finely ribbed cup mussel ( Corbicula fluminalis ) is a freshwater mussel - a species of the family of cup mussels (Corbiculidae). It is a neozoon in Europe that was introduced from the Middle East or Central Asia . The finely ribbed cup mussel and the coarsely ribbed cup mussel ( Corbicula fluminea ) introduced from East Asia are difficult to distinguish on the basis of their housing; they are therefore often referred to collectively as Asian mussel mussels .

features

The evenly folded, moderately expanded housing is up to 24 mm long (30 mm). The lectotype has a ratio of length to height to thickness of 30:30:11 mm (values ​​rounded in each case). Skuza et al. however, give values ​​of 19:19:16 mm as a much more inflated case. In the adult stage it is clearly unequal, the vertebrae are located behind the midline. The vertebrae are thickly arched and lean forward. It is somewhat rounded and triangular in outline. The posterior dorsal margin is slightly convexly rounded and slopes very steeply. The anterior dorsal margin is slightly concavely rounded and falls significantly flatter (than the posterior dorsal margin). The rear end is very rounded, as is the front end. However, there is a slight kink in the anterior margin between the dorsal margin and the ventral margin. The lock plate is wide and has side teeth. In the left valve there are three main teeth and one thick front and one rear posterior tooth. There are also three main teeth in the right flap, but the two posterior teeth are doubled. The two sphincters are about the same size (isomyar). The jacket line is without jacket bay.

The aragonitic shell is comparatively very thick and also has a firm shell. The color of the outside is ocher and sometimes has a faint green tint. The inside can vary between pale blue and purple. The ornamentation consists of parallel, sharp, fine ribs, about 14 to 15 ribs on a centimeter at regular intervals. The periostracum is shiny olive green.

A second morphotype, which differed statistically but not significantly from the lectotype, had a slightly lower housing (in relation to the length) and a centrally located vertebra. The lock plate was a bit narrower, but the ornamentation matches that of the lectotype.

The siphons are thin with rounded openings. Approx. 40 papillae are placed in one or two rows around the inflow siphon, and 12 to 20 papillae around the inflow siphon.

Similar Art

The two types of cup mussels ( Corbicula ) occurring in Central Europe , the finely ribbed cup mussel ( Corbicula fluminalis ) and the coarsely ribbed cup mussel ( Corbicula fluminea ) differ in adult size and in the fineness of the ribs. The finely ribbed shell clam also grows more slowly and remains smaller despite a higher average life expectancy. However, the features mentioned are somewhat variable and there are obviously mixed forms. Molecular genetic evidence has confirmed the two different species, but also found hybrids; that is, the two species can hybridize. However, the two species remain stable overall.

Geographical distribution

Original spread

The original distribution area of ​​the finely ribbed cup mussel includes the Middle East (the type material came from the Euphrates ), Central Asia ( Uzbekistan ) and the Caucasus ( Azerbaijan ) and North Africa. The animals prefer to live on sandy and muddy river bottoms.

Today's distribution

The finely ribbed cup mussel ( Corbicula fluminalis ) occurs today in almost all major Central European rivers, often sympatric with the coarsely ribbed cup mussel ( Corbicula fluminea ).

Reproduction and way of life

The finely ribbed cup mussel ( Corbicula fluminalis ) is a suspension filter that filters microorganisms (phytoplankton etc.) and organic detritus out of the water. Presumably, the main part consists of organic detritus and bacteria on the detritus, since the main weight gain was observed in the winter half of the year, when the proportion of phytoplankton is very low. The spawning times were accordingly in October and March. Sexual maturity can be reached after half a year and with a case length of 7 mm, but usually sexual maturity is only reached after a year.

According to studies made on specimens from the Rhine, the species is largely segregated, only a small part (3%) is hermaphroditic. In other populations, the proportion of hermaphrodite specimens could be higher. The spawning season begins in October when water temperatures drop below 15 ° C. In October / November about 50% of the individuals released their male sex products into the open water. A second spawning period was observed in March / April, after the water temperature rose from 6.5 ° C (February) to 9 ° C (March) and 11.5 ° C (April), respectively. Sexual maturity is reached at a length of about 7 mm. Rajagopal et al. found no larvae in the gills and therefore assumed that the larvae develop in free water. In France, four cohorts of finely ribbed cupola clams were found in the Midi canals, suggesting a life expectancy of four years.

Alexei V. Korniushin found contrary results for larval development in specimens of Corbicula fluminalis from Azerbaijan, Uzbekistan and Egypt. All animals examined were simultaneous hermaphrodites. Larvae with a D-shaped prodissoconch were found in the gills; the specimens measured 185 ± 11 µm. This suggests that the breeding season is relatively short. The contradictions to the observations of Rajagopal et al. He explains (no brood care) by the fact that brood care for Corbicula fluminalis is either optional or that Rajagopal specimens with larvae have not been found only because the incubation time of the larvae is probably very short.

First of all, the study by Renard et al. Is interesting, who found three taxa of the genus Corbicula in French rivers with the help of morphometric and molecular biological methods . However, morphometric and molecular biological data did not agree. The third taxon that was found in the Rhone agrees morphologically with Corbicula fluminea , but is molecularly biologically as far as Corbicula fluminea and Corbicula fluminalis as these two taxa are from each other. Pigneur et al. continued these investigations and came to the conclusion that the third fluminea -like taxon can be identified with Corbicula leana , originally from Japan .

Taxonomy

The taxon was set up in 1774 by Otto Friedrich Müller as Tellina fluminalis . It is considered a valid taxon today. The lectotype of Tellina fluminalis Müller, 1774 is kept in the Zoological Museum of the University of Copenhagen (ZMUK). However, the size of the taxon is hotly debated. Some researchers have identified some African Corbicula species as subspecies of Corbicula fluminalis . This would extend the geographic distribution of the species to large parts of Africa.

paleontology

The occurrence of Corbicula fluminalis in various river terraces of the middle Elbe and Saale areas during the Middle Pleistocene is significant . The finely ribbed cup mussel was first detected here in 1911 in terrace gravel of the Unstrut , known as the Körbisdorfer terrace and belonging to the Holstein warm period . In the further course, evidence was also found in terraces of the same age in the Saale, the Salzke and the Wipper ; in the latter, the occurrence of Corbicula fluminalis correlates with the terrace level of the Homo erectus site in Bilzingsleben . Possibly the occurrence of the mussel species in the Middle Pleistocene of the middle Elbe and Saale region is related to the rising salt brines of the Zechstein saline, which caused a general salinization of the rivers. Since there is no evidence from river terrace gravel in the subsequent warm periods of the Pleistocene, it can be assumed that this was a one-off event. Corbicula fluminalis is an important stratigraphic indicator in the region.

Individual evidence

  1. ↑ a b c Alexei V. Korniushin: A revision of some Asian and African freshwater clams assigned to Corbicula fluminalis (Müller, 1774) (Mollusca: Bivalvia: Corbiculidae), with a review of anatomical characters and reproductive features based on museum collections. Hydrobiologia, 529: 251-270, 2004.
  2. ↑ Lidia Skuza, Anna Maria Łabęcka, Józef Domagała: Cytogenetic and Morphological Characterization of Corbicula fluminalis (OF Müller, 1774) (Bivalvia: Veneroida: Corbiculidae): Taxonomic Status Assessment of a Freshwater Clam. Folia biologica, 57 (3-4): 177-185, 2009 doi : 10.3409 / fb57_3-4.177-185
  3. ↑ Markus Pfenninger, F. Reinhardt, B. Streit: Evidence for cryptic hybridization between different evolutionary lineages of the invasive clam genus Corbicula (Veneroida, Bivalvia). Journal of Evolutionary Biology, 15: 818-829, 2002 doi: 10.1046 / j.1420-9101.2002.00440.x .
  4. ^ A b S. Rajagopal, G. van der Velde, A. bij de Vaate: Reproductive biology of the Asiatic clams Corbicula fluminalis and Corbicula fluminea in the river Rhine. Archives for Hydrobiology, 149: 403-420, 2000 ResearchGate .
  5. ^ E. Renard, V. Bachmann, ML Cariou: Morphological and molecular differentiation of invasive freshwater species of the genus Corbicula (Bivalvia, Corbiculidea) suggest the presence of three taxa in French rivers. Molecular Ecology, 9 (12): 2009-2016, 2000 doi: 10.1046 / j.1365-294X.2000.01104.x
  6. ↑ Lise-Marie Pigneur, Jonathan Marescaux, Kathleen Roland, Emilie Etoundi, Jean-Pierre Descy, Karine Van Doninck: Phylogeny and androgenesis in the invasive Corbicula clams (Bivalvia, Corbiculidae) in Western Europe. BMC Evolutionary Biology, 11: 147, 15 pp., 2011 Abstract
  7. ↑ Otto Friedrich Müller: Vermium terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaecorum, non marinorum, succincta historia. vol. 2, pp. I-XXVI, 1-214 , Havniæ / Copenhagen & Lipsiæ / Leipzig, Heineck & Faber, 1774 Online at www.biodiversitylibrary.org (p. 205)
  8. ↑ MolluscaBase: Corbicula fluminalis (OF Müller, 1776)
  9. ↑ L. Siegert and W. Weißermel: The Diluvium between Halle ad S. and Weissenfels. Treatises of the Prussian Geological State Institute NF 60: Berlin, 1911
  10. ↑ R. Lehmann: The Diluvium of the lower Unstrut valley from Sömmerda to the mouth. Yearbook of the Halle Association for the Exploration of Central German Mineral Resources and Their Exploitation 3: 89–123, 1922
  11. ↑ D. Mania, M. Altermann, G. Böhme, K. Erd, K. Fischer, W.-D. Heinrich, C. Kremenetzki, J. van der Made, D.-H. May, R. Musil, E. Pietrzeniuk, T. Schüler, E. Vlcek and W. Steiner: The travertines in Thuringia and in the Harz foreland. Hallesches Jahrbuch für Geoswissenschaften, Series B, Supplement 17: 1–83, 2003
  12. ↑ T. Laurat and E. Brühl: Old Palaeolithic finds from the Körbisdorfer gravel in the Geiseltal (Neumark-Nord 3/2) - report on the excavations in 2003 and 2004. In: D. Mania and work group (ed.): Neumark -Nord - An interglacial ecosystem of the Middle Paleolithic man. Publications of the State Office for Monument Preservation and Archeology Saxony-Anhalt 62: 121–134, 2010