Glycymeris arabica
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Glycymeris arabica |
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| ( H. Adams , 1871) |
The sea almond , also common velvet clam ( Glycymeris glycymeris ) is a species of clam living in the sea from the family of velvet clams (Glycymerididae, order of the Arcida ). It is native to the western Indian Ocean including the Red Sea. In 1939 it was detected in the Suez Canal , and from 1966 there is also evidence for the Israeli coast, but the species does not seem to have established itself there as a Lessepsian immigrant .
features
The evenly folded, moderately expanded case is roughly triangular in outline; the rear edge is somewhat truncated and slightly elongated. It is almost equilateral, with the vertebrae just slightly in front of the midline. It reaches a maximum case length of 2 cm (3 cm: Zenetos et al.), With about the same case height and a thickness that is about two thirds of the case length and height. Henry Adams gives a ratio of length to height to thickness of 18:18:12 mm. The anterior margin is very slightly arched and drops off steeply, the posterior dorsal margin is almost straight and falls flat. The posterior margin is slightly truncated, the transition from the dorsal margin to the posterior margin almost angled. The front edge is well rounded. The moderately high and prominent vertebrae are slightly curled backwards. The ligament lies externally in front of and behind the vertebra.
The taxodontic lock rim is strongly curved, up to 12 teeth of the same size are present in front of the vertebra, and up to 14 teeth in the back. The surface line is not indented. The two sphincters are rounded, square and the same size.
The ornamentation consists of up to 30 low, flattened ribs with narrower spaces. The ribs have very fine, recessed radial striae. The inner edge of the case is notched. The base color of the shell is whitish to beige with brown to reddish brown spots or zigzag lines running roughly parallel to the edge. On the inside there is usually a brown-black field in the rear ventral part of the housing.
Similar species
Glycymeris arabica differs from Glycymeris glycymeris in its slightly oblique-triangular outline with a truncated rear edge and a slightly angled transition from the dorsal edge and the rear edge. In addition, the species remains significantly smaller.
Geographical distribution, habitat and way of life
The species is found in the western Indian Ocean including the Red Sea and the Gulf of Suez . It has so far been detected once off the Israeli coast, but has not established itself there. The proof is also still a bit uncertain as the copy was damaged.
The species lives in shallow water on sandy bottoms where it actively moves. The specimen off the Israeli coast was dredged from a water depth of 46 meters. The animals are suspension filter feeders .
Taxonomy
The taxon was introduced into the literature in 1871 by Henry Adams under the original binomial Axinaea (Pectunculus) arabica . It is now placed in the genus Glycymeris da Costa, 1778.
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. 131)
- 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. 278/79)
Individual evidence
- ^ A b Henry Adams: Descriptions of twenty-six new species of shells collected by Robert M'Andrew, Esq., In the Red Sea. Proceedings of the Zoological Society of London, 1870: 788-793, London 1871 Online at www.biodiversitylibrary.org .
- ↑ Theodoros Tzomos, Miltiadis-Spyridon Kitsos, Drosos Koutsoubas, Athanasios Koukouras: Evolution of the entrance rate and of the spatio-temporal distribution of Lessepsian Mollusca in the Mediterranean Sea. Journal of Biological Research-Thessaloniki, 17: 81–96, 2012 PDF
- ↑ MolluscaBase: Glycymeris arabica (H. Adams, 1871)