Arca navicularis
| Arca navicularis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Arca navicularis |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Arca navicularis | ||||||||||||
| Bruguière , 1789 |
Arca navicular is a shell - type from the family of ark shells (Arcidae) in the order of Arcida .
features
The evenly folded, moderately expanded housing is up to about 5 cm long and up to about 2.5 cm high. In outline, it is rounded, rectangular to inverted trapezoidal, with an almost straight upper edge (longest stretch) and a very clearly pronounced central sine, which causes a more or less distinct indentation on the only slightly curved ventral edge. The rear edge forms an acute to obtuse angle with the dorsal edge and is more or less indented. The anterior edge, on the other hand, forms an obtuse to rectangular angle with the dorsal edge and is straight to slightly curved. The valves are clearly inaequilateral (unequal-sided), that is, they are clearly extended backwards in relation to the vertebra . The vertebrae are thus in the front half of the housing, but closer to the center, and are twisted towards the front. They are relatively far apart.
From the vertebrae extend up to 27 (up to 50) radial, slightly curved ribs, which are cut by lines of growth. In the area of the central sinus, the ribs are slightly narrower and straight. The ribs and growth lines give the surface a rough appearance or the ribs can become knotty in the cut area. The surface is covered by a thick, leafy (or hairy) periostracum , which is mostly only preserved at the edge. The basic color is usually white to cream-colored, with irregular, sloping brown bands in different intensely brown tones. The inside of the shell is bluish-purple with a narrow, dark, not indented edge.
The lock edge is long and straight. The lock is taxodont (same-toothed), which means it consists of many, small, approximately equal-sized teeth. The external ligament is usually short and diamond-shaped. It lies symmetrically between the vertebrae. Markus Huber also includes shapes with asymmetrical rhombuses or even two rhombic ligament fields.
The sphincters are about the same size, the surface line is indented. The byssus opening is relatively large, so the byssus retractor muscle or the muscle insertion mark is also very large. The two flaps open a little at the front edge to allow the byssus to pass through.
Geographical distribution and habitat
The species has an Indo-Pacific distribution and is also found in the Red Sea . The depth distribution ranges from the intertidal area to about 70 meters water depth.
The animals are attached to rocks or corals with byssus threads. They filter microorganisms out of the water.
Taxonomy
The taxon is said to have been founded in 1789 by Jean-Guillaume Bruguière . So far only the (later?) Publication from 1792 could be found. When listing the new taxon, Bruguière referred to Figure 533 on Plate 54 of the seventh volume by Johann Hieronymus Chemnitz New Systematic Conchylia Cabinet. The specimen from Chemnitz is said to have come from the West Indies, according to him. Bruguière gives Sainte-Domingue ( Santo Domingo , Dominican Republic?) As type locality; possibly he had more copies available. Markus Huber, on the other hand, writes that the specimen depicted by Chemnitz comes from the Indo-Pacific. He probably considers the information from Chemnitz and Bruguière to be erroneous. The taxon is (still today) placed in the genus Arca Linnaeus, 1758. The genus Arca has been split into several genera since the times of Bruguière.
Markus Huber regards the species as very variable and also includes Navicula subnavicularis Iredale, 1939, as a synonym in the taxon. Further synonyms are: Arca cumingi H. Adams & A. Adams, 1858, Arca fuscomarginata Dunker, 1871, Arca linter Jonas, 1845, Arca subquadrangula Dunker in Philippi, 1847, Arca symphenacis PG Oliver & Chesney, 1994 and Bentharca excavata Hayami & Kase , 1993.
literature
- Peter Graham Oliver, Kevin Thomas (pictures): Bivalved seashells of the Red Sea. 330 pp., Wiesbaden, Hemmen et al. a., 1992, p. 33.
- Markus Huber: Compendium of bivalves. 901 S., Hackenheim, ConchBooks, 2010, ISBN 978-3-939767-28-2 (hereinafter abbreviated to Huber, Compendium of Bivalves with corresponding page number)
- Wilhelm Kobelt: The genus Arca L. In illustrations according to nature with descriptions. Systematic Conchylia Cabinet by Martini and Chemnitz, 8 (2): 1-238, Nuremberg 1891 Online at www.biodiversitylibrary.org (p. 51/52), plate 4, Fig . 7 .
Individual evidence
- ^ A b Johann Hieronymus Chemnitz: New systematic Conchylien-Cabinet. Seventh band. With three and thirty copper panels painted from nature and illuminated by vivid colors. S. 1-356, Tab. 37-69, Raspe, Nürnberg 1789 Online at Biodiversity Heritage Library , S. 184 ,.
- ^ Lovell Augustus Reeve: Conchologia Iconica, or, Illustrations of the Shells of Molluscous Animals. Vol. 2, London, Reeve Brothers, 1843-1844 online at www.biodiversitylibrary.org (Plate 11 Fig. 70).
- ↑ a b c d Huber, Compendium of Bivalves, p. 129 (left fig., 2nd row from above), p. 559.
- ^ Jean-Guillaume Bruguière: Encyclopédie méthodique. Histoire naturelle des vers. Tome premier. (ABE-CON). I-XVIII (= 1-18), pp. 1-757, Panckoucke, Paris 1792 [127 ,% 22panX% 22: 0.5,% 22panY% 22: 0.591,% 22view% 22:% 22info% 22,% 22zoom% 22: 1.037} Göttingen Digitization Center], here p. 99.
- ↑ a b MolluscaBase: Arca navicularis Bruguière, 1789