Whitish cockle
| Whitish cockle | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Parvicardium scabrum | ||||||||||||
| ( Philippi , 1844) |
The whitish cockle ( Parvicardium scabrum , syn. Parvicardium nodosum ) is a shell - type from the family of cockles (Cardiidae) in order Cardiida . It is also found in the North Sea and the Mediterranean .
features
The equal-folding, inflated housing is broad-egg-shaped to rounded-triangular in outline. The dimensions given are: 8 mm wide, 7 mm high and 5.5 mm in cross-section (thickness). Exceptionally, the housing is up to 15 mm long. It is slightly unequal; the small vertebrae are just in front of the midline. The anterior and posterior dorsal edges are roughly the same length and sloping. The rear edge is slightly truncated, the front edge is well rounded, as is the ventral edge. A weak keel that pulls from the vertebra to the rear edge can easily separate the rear part of the case from the rest of the case. However, it is not developed or noticeable in all specimens. The lunula is small and narrow. The ligament, on the other hand, is strongly developed and sits on a short nymph . The lock is poorly developed. In the right valve there are two main teeth, two front posterior teeth and one posterior posterior tooth. The upper anterior posterior tooth is very small. The left valve has two main teeth and an anterior and posterior posterior tooth each; the anterior posterior tooth is significantly larger. The surface line is clear, it is not indented. There are two sphincters of roughly the same size.
The shell is comparatively thin and slightly translucent, but still very solid. The surface is ornamented with 25 to 28 radial ribs. The spaces between the ribs are narrower than the ribs, usually only about half as wide. The ribs on the front and rear housing section carry numerous small crossbars, which can develop into blunt, wide scales and small blunt, outwardly curved thorns, especially towards the edge of the housing. The ribs in the rear part of the case usually develop immediately blunt scales instead of the crossbeams, which also quickly become blunt thorns towards the edge of the case. The ribs are crossed by fine growth strips parallel to the edge. Specimens whose scales or thorns are weakly developed are given a grid-like pattern. Small, shallow pits can be formed in the mostly smooth spaces between the ribs. This is particularly the case with specimens from the northern North Atlantic. The inner edge of the housing is notched analogous to the ribs and spaces. The furrows of the ribs on the inside of the flaps extend to the approach of the surface line. The periostracum is a thin organic coating and is straw yellow in color, mostly only preserved on the ventral margin. The color varies from dirty-whitish to whitish-beige, on the vertebrae also with a light yellow or orange tint. Inside it is tinted white or yellowish to orange.
The soft body of the animal is translucent. The edge of the mantle is drawn out into filaments that are colored whitish. The siphons are light yellow in color, the base is whitish.
Similar species
The oval carpet shell ( Timoclea ovata ) is clearly more triangular in outline and has a distinct jacket bay. The elements parallel to the edge are made much stronger, the ribs are briefly interrupted at the crossing points; A grid pattern is created in perception. In addition, the latter species has no thorns on its ribs. and owns. The triangular cockle ( Parvicardium exiguum ) is significantly more distended (thicker) and also more oblique and more triangular.
In Parvicardium minimum , the scales and thorns on the ribs are sharp or pointed. In addition, there are more ribs on average. The outline of the case of this type is much more rounded.
Geographical distribution and habitat
The distribution area of the species extends from Norway to Morocco , and into the Mediterranean . It is also found in the waters around Madeira and the Canary Islands .
The animals dig in muddy, sandy-muddy or muddy-gravelly soils, occasionally also between the roots of small algae ( Corallina ). They come from about 9 m water depth to about 100 m water depth. Occasionally, however, they also penetrate to greater depths (north triangle: 740 m).
Taxonomy
The taxon was introduced into scientific literature in 1844 by Rudolph Amandus Philippi in the original combination Cardium scabrum . The species also appears in older literature under the name Cardium nodosum or Parvicardium nodosum (Turton, 1822). Cardium nodosum Turton, 1822, however , was preoccupied by Cardium nodosum Montagu, 1803 and is therefore invalid.
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. 99 as Parvicardium nodosum )
- Guido Poppe. Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 (p. 98)
On-line
- Marine Bivalve Shells of the British Isles: 'Parvicardium scabrum (Philippi, 1844) (website of the National Museum Wales, Department of Natural Sciences, Cardiff) (accessed May 21, 2017).
- Marine Species Identification Portal: Parvicardium scabrum (Philippi, 1844) (accessed May 21, 2017).
- Parvicardium scabrum (Philippi, 1844) Conchological Society of Great Britain and Ireland (accessed May 21, 2017).
Individual evidence
- ↑ Rudolph Amandus Philippi: Enumeratio molluscorum Siciliae cum viventium tum in tellure tertiaria fossilium, quae in itinere suo observavit. Volume secundum continens addenda et emendanda, nec non comparationem faunae recentis Siciliae cum faunis aliarum terrarum et com fauna periodi tertiariae. IV + 303 S., Eduard Anton, Halis Saxorum / Halle, 1844. Online at www.biodiversitylibrary.org (p. 38) Taf, 14, Fig. 16
- ↑ MolluscaBase: Parvicardium scabrum (Philippi, 1844)