Acar plicata
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| ( Dillwyn , 1817) |
Acar plicata is a shell - type from the family of ark shells (Arcidae) in the order of Arcida . Originally native to the Pacific and Indian Oceans, including the Red Sea, the species immigrated to the eastern Mediterraneanthrough the Suez Canal as Lessepsian immigrants inthe 1970s. But it has not established itself there.
features
The equally flared, strongly expanded housing has a maximum length of 30 mm. It is strongly unequal to the vertebrae in the front third of the case. The vertebra is wide and curled forward. It is trapezoidal in outline with a straight to slightly arched dorsal edge and an obliquely truncated, slightly arched rear edge. The lower rear corner of the housing tapers or can even be drawn out to a point. The front margin is moderately arched and the ventral margin almost straight to slightly concave. In the anterior part of the ventral margin there is a small indentation for the byssus . The two flaps therefore gape slightly. A more or less pronounced keel runs from the vertebra to the rear lower end of the housing.
The external ligament lies behind the vertebrae. The lock is taxodont, the edge of the lock is slightly arched. The front teeth are separated from the back row of teeth by a toothless gap in the middle. The teeth become larger towards the outside and diverge more strongly towards the outside. The two sphincters are roughly the same size. The muscle scars are slightly raised.
The aragonitic shell is thick and tightly skinned. The ornamentation consists of lamellas parallel to the edge, which intersect with radial ribs. The spaces between the ribs are slightly wider than the ribs themselves. The ornamentation appears reticulate when the ribs and lamellas are slightly worn. Especially in the rear part of the housing, the slats stand out like roof tiles; the edge of the housing is therefore often very irregular. The inner edge of the case is notched. The color varies from whitish to beige, occasionally with an orange or pink tint.
Geographical distribution, habitat and way of life
The species has a very large range in the western Pacific and in the warmer parts of the Indian Ocean including the Red Sea . It was detected in the Suez Canal as early as 1939 and immigrated to the southeastern Mediterranean in the 1970s. However, it was unable to establish itself in the Mediterranean, because it was later no longer found there.
The animals live sessile with byssus threads attached to corals, stones and hard ground. They are suspension filter feeders.
Taxonomy
The taxon was first described in 1817 by Lewis Weston Dillwyn as Arca plicata . The species was generally recognized today as part of the genus Acar Gray, in 1857. It is de facto type species of the genus Acar , since the formal type species of the genus, Byssoarca divaricata GB Sowerby I, 1833 is a younger synonym of Arca plicata Dillwyn, 1817.
In older works, Chemnitz can still be found as the author of the taxon. The work Neues Systematisches Conchylien-Cabinet by Johann Hieronymus Chemnitz , in which the original illustration appeared, was rejected by the International Commission for Zoological Nomenclature as being used for nomenclature purposes and declared invalid because the work does not use binomial nomenclature.
literature
- Peter Graham Oliver, Kevin Thomas (pictures): Bivalved seashells of the Red Sea. 330 pp., Wiesbaden, Hemmen et al. a., 1992 ISBN 3-925919-08-2 (p. 34)
- Argyro Zenetos, Serge Gofas, Giovanni Russo, José Templado: CIESM Atlas of Exotic Species in the Mediterranean. Vol.3 Mollusca. CIESM (Frédéric Briand, ed.), Monaco, 2003 ISBN 92-990003-3-6 (p. 210/11)
Individual evidence
- ^ Wilhelm Kobelt: The genus Arca L. In illustrations after nature with descriptions. Systematic Conchylia Cabinet by Martini and Chemnitz, 8 (2): 1-238, Nuremberg 1891 Online at www.biodiversitylibrary.org (p. 195), plate 1 , plate 47 .
- ↑ Lewis Weston Dillwyn: A descriptive catalog of recent shells: arranged according to the Linnæan method; with particular attention to the synonymy. Vol. 1. pp. 1–580, Printed for J. and A. Arch, London 1817 Online at www.biodiversitylibrary.org (pp. 227/28)
- ↑ a b MolluscaBase: Acar plicata (Dillwyn, 1817)