Gray slug
| Gray slug | ||||||||||||
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Gray slug ( Arion circumscriptus ) |
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| Scientific name | ||||||||||||
| Arion circumscriptus | ||||||||||||
| ( Johnston , 1828) |
The gray slug ( Arion circumscriptus ) is a slug from the family of slugs (Arionidae), which is subordinated to the land snails (Stylommatophora). The species is difficult to distinguish from two closely related species because the coloration of the species is very variable. Newer investigations doubt the independence of the species.
description
The gray slug measures about 3 to 5 cm when stretched out. The back is steel gray to bluish gray. The side stripes (bandages) are relatively wide and usually a little darker in color than the back. They are set off from the back by a light strip. However, this can almost be missing. Another light stripe follows towards the sole. The sole is whitish. The same pattern can be seen on the coat shield, but the stripes are offset from the stripes on the foot. The breathing hole is usually completely or partially enclosed by the hard shoulder.
Occurrence, way of life and distribution
The species often lives on fallen wood in deciduous forests. It feeds mainly on mushrooms and mushroom mycelia. It is common in Central and Western Europe. In the north it occurs in southern Scandinavia. Like many other originally European nudibranch species, the gray slug has now also been introduced to North America.
Systematics
The independence of the species was questioned in 2006 by Sofie Geenen and co-authors. They found in the three species Arion fasciatus (Nilsson, 1823) ( yellow-striped slug ), Arion silvaticus Lohmander, 1937 ( forest slug ) and Arion circumscriptus Johnston, 1828 (gray slug) neither consistent features in the genital anatomy nor sufficient differences in DNA Investigations. They attribute the differences in color to the establishment of color variants through longer phases of self-fertilization. Rowson et al. (2014) also found no differences between Arion silvaticus Lohmander, 1937 and Arion circumscriptus Johnston, 1828, but they stick to Arion fasciatus (Nilsson, 1823) as a separate species.
Should the interpretation of these results be further confirmed, Arion silvaticus Lohmander, 1937 and Arion circumscriptus Johnston, 1828 must be combined into one species ( i.e. Arion circumscriptus Johnston, 1828), while Arion fasciatus (Nilsson, 1823) can be retained as an independent species. All three (or probably only two) species are placed in the subgenus Arion (Carinarion) Hesse, 1926, which is not used by some authors . In the original conception as an independent species, Arion circumscriptus had the following synonyms: Arion ambiguus Pollonera, 1889, Arion bourguignati Mabille, 1868, Arion miser Pollonera, 1887 and Arion subcarinatus Pollonera, 1885.
literature
- Rosina Fechter and Gerhard Falkner: molluscs. 287 pp., Munich, Mosaik-Verlag 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3
- Michael P. Kerney, RAD Cameron, Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg and Berlin 1983, ISBN 3-490-17918-8
- Sofie Geenen, Kurt Jordaens, Thierry Backeljau: Molecular systematics of the Carinarion complex (Mollusca: Gastropoda: Pulmonata): a taxonomic riddle caused by a mixed breeding system. Biological Journal of the Linnean Society, 89 (4): 589-604, London 2006 doi : 10.1111 / j.1095-8312.2006.00693.x
- Ben Rowson, Roy Anderson, James A. Turner, William OC Symondson: The Slugs of Britain and Ireland: Undetected and Undescribed Species Increase a Well-Studied, Economically Important Fauna by More Than 20%. PLOS ONE, 2014 doi : 10.1371 / journal.pone.0091907
