Fragile clam

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Fragile clam
Fragile clam (Cochlodesma praetenue) (from GB Sowerby II, 1859: Plate 2, Fig. 10. [1])

Fragile spoon-mussel ( Cochlodesma praetenue ) (from GB Sowerby II, 1859: Plate 2, Fig. 10.)

Systematics
Superordinate : Anomalodesmata
Order :
Superfamily : Thracioidea
Family : Spoon clams (Periplomatidae)
Genre : Cochlodesma
Type : Fragile clam
Scientific name
Cochlodesma praetenue
( Pulteney , 1799)

The fragile spoonbill ( Cochlodesma praetenue ) is a type of shell from the family of the spoon clams (Periplomatidae). It occurs in the North Atlantic .

features

The unevenly hinged housing reaches a length of up to 38 millimeters. The right flap is more arched and slightly larger. It is unequal, the inward opisthogyrene vertebrae sitting behind the midline in relation to the length of the case. It is egg-shaped in outline. The ratio of width to length is about 1: 1.4 to 1.5. The anterior dorsal margin is longer than the posterior dorsal margin and is also significantly higher. The anterior dorsal margin is clearly convexly rounded and merges into the broadly rounded anterior margin without any noticeable edge or kink. The posterior dorsal margin is straight, the transition to the slightly convex, somewhat truncated-looking posterior margin is slightly angled. The rear edge also merges with the broadly rounded ventral edge at a slight angle. The case gapes a bit at the rear end.

The external ligament is a thin band in front of and behind the vertebrae. The internal ligament sits on a spoon-like protruding process. The lock is toothless. The surface line is indented, the bay roughly reaches the area below the eddy. The ventral part of the mantle bay does not coincide with the mantle edge. The anterior sphincter is smaller than the posterior sphincter. The soft body is whitish. The foot is tongue-shaped.

The whitish shell is thin and fragile, which is what the common name fragile clam refers to. The ornamentation consists of fine dimples arranged in concentric lines. The grain is somewhat coarser at the rear end. The inside edge of the case is smooth. The very thin periostracum is beige to cream-colored; it is mostly limited to the posterior end up to a line that leads from the vertebra to the transition from the posterior end to the ventral margin. Otherwise it is almost completely rubbed off. There is a small crack in the vertebra, which is approximately perpendicular to the length of the case and leads over a short distance to the lower rear end.

Similar species

The fragile spoon-mussel differs from the white bean ( Thracia phaseolina ) in that its rear end, which is only slightly truncated, and the slit in the vertebra .

Geographical distribution and habitat

The species is distributed from Iceland and northern Norway to the Mediterranean . It is also found in the southern North Sea and the western Baltic Sea . It lives in silty sand, sand to sandy fine gravel from about seven meters to 100 meters water depth. The animal lies on one side or flap and buried flat in the sediment. The inflow siphon leads to the sediment surface, but the outflow siphon leads horizontally into the sediment.

Taxonomy

The species was first described by Richard Pulteney as Chama praetenuis . The species is also assigned to the genus Bontaea Brown, 1844 in the older literature . The genus Bontaea Brown, 1844 is a younger, subjective synonym of Cochlodesma Couthouy, 1839; Bontaea is based on Chama praetenuis Pulteney, 1799.

supporting documents

literature

  • Fritz Gosselck, Alexander Darr, Jürgen HJ Jungbluth, Michael Zettler: common names for mollusks of the sea and brackish water in Germany. Mollusca, 27 (1): 3–32, 2009 PDF (p. 29)
  • Rudolf Kilias: Lexicon marine mussels and snails. 2nd edition, 340 pages, Verlag Eugen Ulmer, Stuttgart 1997 ISBN 3-8001-7332-8 (p. 70)
  • 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. 162 as Bontaea praetenue )
  • Guido Poppe. Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 (p. 137)
  • Rainer Willmann: Mussels of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989 ISBN 3-7888-0555-2 (p. 200)

On-line

Individual evidence

  1. ↑ George Brettingham Sowerby II : Illustrated index of British shells. containing figures of all the recent species, with names and other information. XV S., XXIV plate. London, Simpkin, Marshall & Co., 1859 Online at www.biodiversitylibrary.org (plate 2)
  2. ^ Rainer Willmann: Mussels of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989 ISBN 3-7888-0555-2 (p. 200)
  3. ^ Richard Pulteney: Catalogs of the birds, shells, and some of the more rare plants, of Dorsetshire. From the new and enlarged edition of Mr. Hutchins's history of that county. Pp. 1-92, London, Nichols, 1799 (not seen).
  4. ↑ MolluscaBase: Cochlodesma praetenue (Pulteney, 1799)

Web links

Commons : Fragile Spoon Clam ( Cochlodesma praetenue )  - Collection of images, videos and audio files