River mussels

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River mussels
Great river mussel (Unio tumidus)

Great river mussel ( Unio tumidus )

Systematics
Subclass : Autolamellibranchiata
Superordinate : Palaeoheterodonta
Order : Unionida
Superfamily : River mussel-like (Unionoidea)
Family : Common and pond mussels (Unionidae)
Genre : River mussels
Scientific name
Unio
Philipsson , 1788

The river mussels ( Unio ) are a genus within the family of river and pond mussels (Unionidae). It is widespread in running and still waters in Europe, North Africa and the Middle East; a species also occurs in East Asia.

features

The representatives of the Unio genus usually have large, single-sided cases over 40 millimeters in length. Most species have a rounded, short to elongated egg-shaped or somewhat trapezoidal, also wedge-shaped housing outline. The eddy does not protrude or only slightly. The outside of the housing is typically smooth or has fine grooves or folds, and more rarely it can also be coarsely ribbed. The thick to thin-walled shell consists of an inner aragonitic mother-of-pearl layer , a middle aragonitic prism layer and a thick organic periostracum . The vertebra sits in front of the center, the rear part of the housing longer than the front part. The vertebra is relatively low and carved with coarse, mostly concentric, but also interrupted folds. The area is more or less clearly defined. The lock consists of two main teeth and two posterior teeth in the left valve and one main tooth and one posterior tooth in the right valve ("schizodontes" lock). The brood pouch (Marsupium) occupies all four gill leaves. The development takes place via larvae ( glochidia ) that parasitize on fish gills.

Similar genera

The type of pond mussels ( Anodonta ) differs in the lock; here the "teeth" are missing.

Geographical distribution and habitat

The species of the genus Unio occur in Europe, North Africa and the Middle East. The river mussel is also found in the Amur region and Beringia ( Chukchi Peninsula , Kamchatka and Alaska ). Three species of the genus Unio are also native to Germany: the river mussel ( Unio crassus ), the painter's mussel ( Unio pictorum ) and the large river mussel ( Unio tumidus ). The mussels live in calm and flowing waters.

Taxonomy

The Taxon Unio was set up by Lorens Münter Philipson (also written Philipsson) in 1788 . Type species of the genus is Mya pictorum Linnæus, 1758 by a decision of the International Commission for Zoological Nomenclature. The gender of the genus was defined as masculine.

According to the latest survey by Graf & Cummings (2006) there are only seven species within the genus Unio (see str.). Since then, five species have been added, older taxa that are again considered valid taxa. There are certainly also some fossil species:

supporting documents

literature

  • Daniel L. Graf & Kevin S. Cummings: Paleoheterodont diversity (Mollusca, Trigonioida + Unionoida): what we know and what we wish we knew about freshwater mussel evolution. Zoological Journal of the Linnean Society, 148: 343-394, 2006.
  • Fritz Haas : Superfamilia Unionacea. In: Robert Mertens, Willi Hennig (eds.): Das Tierreich A compilation of recent animal forms, delivery 88, X + 663 S., Walter de Gruyter & Co., Berlin 1969 reading sample from Google Books
  • Jürgen H. Jungbluth and Dietrich von Knorre: Common names of land and freshwater mollusks in Germany (Gastropoda et Bivalvia). Mollusca, 26 (1): 105-156, Dresden 2008 ISSN  1864-5127

Individual evidence

  1. ^ Matthias Schäfer (Ed.): Brohmer - Fauna of Germany. A book of identification of our native fauna. 23rd, revised edition. Quelle & Meyer Verlag GmbH & Co., Wiebelsheim 2010, ISBN 978-3-494-01472-2 , p. 95.
  2. ↑ Anders Jahan Retzius : Dissertatio historico-naturalis sistens nova testaceorum genera. Quam præside DM Andr. J. Retzio (...) ad publicum examen defert Laurentius Münter Philipsson. 23 p., Lundæ / Lund. (Dissertatio Historico-Naturalis). (Berling) 1788. Online GDZ Göttingen Digitization Center (p. 16)
  3. ^ AE Ellis: Proposed use of the plenary powers to validate the currently accepted usage of the generic name "Unio" Philipsson , 1788 (Class Pelecypoda). Bulletin of Zoological Nomenclature , 11: 337, 1956 Online at www.biodiversitylibrary.org
  4. ↑ a b Rafael Araújo, Joaquim Reis, Annie Machordom, Carlos Toledo, María José Madeira, Ignacio Gómez, Juan Carlos Velasco, Javier Morales, José Miguel Barea, Paz Ondina, Iker Ayala: Las náyades de la península Ibérica. Iberus, 27 (2): 7-72, 2009 abstract .
  5. ↑ a b Noureddine Khalloufi, Carlos Toledo, Annie Machordom, Moncef Boumaïza, Rafael Araujo (2011): The unionids of Tunisia: taxonomy and phylogenetic relationships, with redescription of Unio ravoisieri Deshayes, 1847 and U. durieui Deshayes, 1847. Journal of molluscan Studies 77 (2): 103-115. doi : 10.1093 / mollus / eyq046
  6. ↑ Araujo, R., Toledo, C. & Machordom, A .: Redescription of Unio gibbus Spengler, 1793, a West Palaearctic freshwater mussel with hookless glochidia. Malacologia, 51 (1): 131-141, 2009 PDF (5.3 MB).

Web links

Commons : Unio  - collection of images, videos and audio files