Fragile rock drill
| Fragile rock drill | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Saxicavella Jeffreysi | ||||||||||||
| Winckworth , 1930 |
The Fragile rock drill ( Saxicavella jeffreysi ) is a shell - type from the family of Basterotiidae . It also occurs in the North Sea .
features
The equally-hinged to slightly uneven-hinged, non-inflated housing is up to about 10 mm long. It is clearly unequal, the protruding vertebrae are shifted towards the front end (at about 25% of the length of the case). The shape of the casing is crooked and rhomboidal, with gaps at both ends. However, the housing outline is somewhat variable and often somewhat twisted. The dorsal margin is almost straight and rises towards the rear end. The posterior margin is high and sloping downward, the ventral margin is almost straight to slightly convex. The front end is tightly rounded. A weak keel emanating from the vortex and pulling towards the rear lower end of the housing separates the rear housing field from the rest of the housing. The keel is very strong in juvenile cases and weakens in adult cases. Another, but very weak, keel pulls from the vertebra to the lower front end of the housing.
The ligament is a narrow external ligament behind the vertebrae. It sits in the right flap on a triangular plate. The right valve has a central extension that is reminiscent of a weak main tooth. This extension corresponds to a pit in the left flap. According to research on Saxicavella jeffreysi for the development of the castle by Graham Oliver, this extension cannot be called the main tooth, as happened in earlier publications. The surface line is entire.
The dirty white thin shell is slightly translucent and looks fragile. The surface shows rather coarser concentric growth strips and somewhat irregular growth interruptions. The inner edge is smooth. The periostracum is yellowish to pale brown and persists even in adult specimens.
Geographical distribution and habitat
The distribution area of the species extends from southern Iceland and northern Norway to the Mediterranean and the Canary Islands .
The animals live buried in muddy, sandy and gravelly soils from about 7 to 240 meters water depth. The species is a commensal of species of the genus Maxmuelleria .
Taxonomy
The taxon was founded in 1930 by Ronald Winckworth . It is not a noun novum (new name) in the sense of a substitute name, but a new scientific name based on an earlier description and illustration of " Panopaea plicata Montagu" by John Gwyn Jeffreys . The species Mytilus plicatus described by George Montagu , which Jeffreys then placed in the genus Panopaea , is not a species established by Montagu, but a misidentification of Mytilus plicatus Gmelin, 1791. A misidentification, so " Mytilus plicatus Montagu" is not an available name in In the sense of the nomenclature rules, it is a nomen nullum and therefore cannot be replaced by a substitute name. Ronald Winckworth only referred to the description and illustration in Jeffreys when he proposed the new species Saxicavella jeffreysi . Therefore, only this description can be used to justify the species, and only the material used by Jeffreys is the type material.
The species is considered to be the type species of the genus Saxicavella P. Fischer, 1878.
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. 147)
- 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. 131)
- Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 (p. 179)
On-line
Individual evidence
- ^ A b P. Graham Oliver: Description of Atopomya dolobrata gen. Et sp. nov .: First record of bacterial symbiosis in the Saxicavellinae (Bivalvia). Journal of Conchology, 41 (§): 359-367, 2013 PDF
- ^ Ronald Winckworth: Notes on Nomenclature. Proceedings of the Malacological Society of London, 19: 14-16, London 1930.
- ^ John Gwyn Jeffreys: British conchology, or, An account of the Mollusca which now inhabit the British Isles and the surrounding seas. Vol. 3. John Van Voorst, London 1865 Online at www.biodiversitylibrary.org (p. 75), plate 3
- ^ Georg Montagu: Supplement to Testacea Britannica. SI-V, 1-183, London, White 1808. Online at www.biodiversitylibrary.org (p. 70)
- ↑ MolluscaBase: Saxicavella jeffreysi Winckworth, 1930