Arca tetragona

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Arca tetragona
Arca teragona

Arca teragona

Systematics
Order : Arcida
Superfamily : Arcoidea
Family : Ark clams (Arcidae)
Subfamily : Arcinae
Genre : Arca
Type : Arca tetragona
Scientific name
Arca tetragona
Poli , 1795

Arca tetragona is a type of mussel from the family of ark mussels (Arcidae).

features

The strongly bulbous, equally-hinged case has an approximately elongated-rhombic outline with a maximum length of 4 cm. The rear part of the housing is strongly drawn out and significantly longer than it is high; Overall, the case is about twice as long as it is high. The vertebra sits about a quarter (the total dorsal length) from the anterior end. The vertebrae protrude over the almost straight, very long dorsal edge. The straight to slightly concave rear edge slopes downwards, the transition to the ventral edge is tightly rounded, usually even angled. The front edge is slightly to strongly convex and drops very steeply. The ventral margin is slightly arched, straight to slightly concave. In the anterior region of the ventral margin the valves gape very clearly, the passage of the byssus. Starting from the vertebra, a sharp back runs to the angle between the posterior and ventral edge. The middle of the case is flattened or even slightly sunk.

The lock edge is straight, the lock is taxodont . The duplivincular ligament extends over the entire width of the lock rim. The small teeth of the lock sit on a narrow plate, divided into two groups. The front teeth (approx. 30) are usually short, the rear teeth (approx. 15) are slightly longer and are usually tilted at an angle to the edge of the lock. The innermost teeth can be worn down and lost.

The skin is relatively thin, but not translucent. The ornamentation consists of dense, radial ribs that are interrupted by growth stops and are knotty. The rear housing section has only a few broad and knotty ribs. The periostracum is dark brown and has short bristles, only the bristles on the rear carina are significantly longer.

The two sphincters are not the same, the anterior sphincter is slightly smaller than the posterior sphincter.

Geographical distribution and habitat

The range of the species extends from Norway to Morocco and the Mediterranean . It has also been proven around the Cape Verde Islands , the Canary Islands , Madeira and the Azores .

The species occurs from just below the low water line to a depth of 120 meters. However, it was allegedly already brought from a water depth of 2664 meters (Nordsieck). Krylova gives 1557 meters as the maximum water depth.

Taxonomy

The first description of this species was made by Giuseppe Saverio Poli in 1795. It is the type species of the genus Tetrarca Nordsieck, 1969, which, however , is treated by the World Register of Marine Species as a synonym of Arca Linné, 1758. Some authors accept Tetrarca as a subgenus of Arca .

Synonyms of the species are: Arca argenvillea Risso, 1826, Arca britannica Reeve, 1844, Arca cardissa Lamarck, 1819, Arca fusca Lightfoot, 1786, Arca papillosa Petit de la Saussaye, 1869 and Tetrarca imbricata ibizenca Nordsieck, 1969.

supporting documents

literature

  • Fritz Nordsieck : The European sea shells (Bivalvia). From the Arctic Ocean to Cape Verde, the Mediterranean Sea and the Black Sea. 256 p., Gustav Fischer Verlag, Stuttgart 1969 (p. 20)
  • Guido Poppe and Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 (p. 42)

On-line

Individual evidence

  1. ^ P. Graham Oliver, Rudo von Cosel: Taxonomy of Tropical West African Bivalves. IV. Arcidae. Bulletin du Muséum national d'Histoire naturelle du Paris, 4th series, secion, 14A (2): 293–381, Paris 1992 PDF
  2. ^ EM Krylov: Bivalves of seamounts of the north-eastern Atlantic. Part I. In: AN Mironov, AV Gebruk and AJ Southward (Eds.): Biogeography of the North Atlantic seamounts. Pp. 76-95, Moscow 2006. PDF
  3. Jump up ↑ Giuseppe Saverio Poli: Testacea Vtrivsqve Siciliae Eorvmqve Historia Et Anatome Tabvlis Aeneis Illvstrata A Iosepho Xaverio Poli Serenissimi Regii Siciliarvm Principis Institvtore Tomvs Secvndvs. SI-XLIX, pp. 75–264, Parmae ​​/ Parma, Regio Typographeia, 1795 Online at www.gallica.bnf.fr (pp. 137/8)
  4. ^ A b World Register of Marine Species: Tetrarca Nordsieck, 1969
  5. ^ Markus Huber: Compendium of Bivalves. 901 S., Hackenheim, ConchBooks, 2010 ISBN 978-3-939767-28-2
  6. ↑ World Register of Marine Species: Arca tetragona Poli, 1795

Web links

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