Asperarca

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Asperarca
Asperarca nodulosa

Asperarca nodulosa

Systematics
Subclass : Pteriomorphia
Order : Arcida
Superfamily : Arcoidea
Family : Ark clams (Arcidae)
Subfamily : Bathyarcinae
Genre : Asperarca
Scientific name
Asperarca
Sacco , 1896

Asperarca is a shell - genus from the family of ark shells (Arcidae).

features

The housings, which can be equally or slightly differently folded, are roughly elongated-rhombic, rectangular to wedge-shaped. They are moderately bloated (thick), small and reach a maximum length of 1.5 cm. The rear part of the housing is very strongly drawn out; Overall, the case is about twice as long as it is high. The vertebrae sit about a quarter (the total length of the dorsal margin) from the anterior end and are curled forward (prosogyr). The rear housing part is therefore more than twice as long as the front housing part. The dorsal margin is long and straight. The posterior dorsal margin merges at an obtuse angle into the posterior margin, the transition between the anterior dorsal margin and the anterior margin is rounded, angular and truncated. The front edge merges continuously into the ventral edge. The rear edge and ventral edge, on the other hand, form an acute angle, the transition between the rear edge and the ventral edge is tightly rounded. The dorsal field is comparatively wide. The recess for the byssus is only indicated to moderately wide.

The ligament lies outside in front of and behind the vertebrae (opisthodet). The lock edge is narrow and slightly curved. The short, upright or slightly tilted teeth are divided into two groups, interrupted by a short toothless area under the vertebrae. The back teeth are usually a little longer and more tilted.

The shell is firm and not translucent. The ornamentation consists of distinct concentric ribs that z. T. are like tiles on top of each other. The intersection areas with finer, closely spaced radial ribs are knotty to prickly. The periostracum is thin and can be drawn out into bristles. There are two sphincters of different sizes, the anterior sphincter being slightly smaller than the posterior sphincter. The muscle attachment points are slightly raised.

Geographical distribution and habitat

The distribution area of ​​the genus Asperarca is limited to the eastern Atlantic up to the level of the Mediterranean and the Mediterranean itself.

The animals attach themselves to deep-sea corals, stones and other hard grounds with byssus. They occur from about 200 meters water depth to about 4000 meters water depth. They are rarely found in shallower water.

Taxonomy

The genre was established in 1896 by Federico Sacco . Type species is Arca nodulosa Müller, 1776. While older works mostly understand the genus as a synonym of Acar Gray, the taxon is rated as an independent genus in more recent publications and in the World Register of Marine Species .

The species Asperarca xenophoricola (Kuroda, 1929), which was placed in the genus Asperarca before 2010, was identified by Markus Huber as a type of a new genus Xenophorarca Huber, 2010.

supporting documents

literature

  • Jonata de A. Francisco, José Carlos N. de Barros, Silvio Felipe B. de Lima: Five new species of Arcidae from Brazil with description of new genus: Paranadara (Mollusca: Bivalvia). Journal of the Marine Biological Association of the United Kingdom, 92 (5), 1139-1150, 2012 doi : 10.1017 / S0025315411000919
  • Raymond Cecil Moore (Ed.): Treatise on invertebrate paleontology. Mollusca, 6, Bivalvia 1. XXXVIII, 489 pp., New York, 1969 (pp. N254).
  • 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. 22)

Individual evidence

  1. ^ Luigi Bellardi (continued after 1889 by Federico Sacco): I molluschi dei terreni terziarii del Piemonte e della Liguria. 92 pp., Torino / Turin, Stamperia Reale, 1872–1904 (1896). Online at www.biodiversitylibrary.org (p. 10)
  2. ^ A b World Register of Marine Species: Asperarca Sacco, 1896
  3. ↑ Marine Bivalve Shells of the British Isles: Asperarca nodulosa (Müller, 1776) (website of the National Museum Wales, Department of Natural Sciences, Cardiff)
  4. ^ Markus Huber: Compendium of Bivalves. 901 S., Hackenheim, ConchBooks, 2010 ISBN 978-3-939767-28-2

Web links

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