Small wolverine snail
| Small wolverine snail | ||||||||||||
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Lesser wolverine snail ( Merdigera obscura ) |
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| Scientific name | ||||||||||||
| Merdigera obscura | ||||||||||||
| ( OV Müller , 1774) |
The small wolverine snail ( Merdigera obscura ), also referred to by some authors as the small tower snail , is a type of snail of the family wolverine snails (Enidae) from the subordination of land snails (Stylommatophora).
features
The right-hand wound, egg-shaped-conical cases are 8.5 to 10.5 mm high (6.5 to 11 mm) and 3 to 4 mm wide. There are six to seven turns. The first turns are moderately convex at the periphery, the last turns are very flat. Young animals still have a cone-shaped housing with edged turns at the base. The mouth is egg-shaped and pointed at the top; the egg shape is inclined to the longitudinal axis of the housing. The whitish to light reddish mouth edges are only slightly bent and only slightly thickened. The points of attachment of the mouth edge to the previous turn are not connected to one another by a callus. The mouth is toothless. The navel is shaped like a wide slit.
The housings are yellowish-horn-colored to chestnut brown. The shell is comparatively thin, the surface matt. The surface of the embryonic convolutions is smooth, the following convolutions have somewhat irregular radial folds or strips of growth. However, the housings are often coated with a dried slime film, especially in young animals, with soil and excrement residues.
The soft body of the animals is gray to dark gray in color. The sides of the body and the foot are a little lighter. The upper tentacles are comparatively long. The lower tentacles, however, only reach about a quarter of the length of the upper tentacles.
In the sexual apparatus, the spermatic duct (vas deferens) separates early from the egg duct (sperm duct). It is thin, wrapped around the stem of the spermathec and the vagina, and comparatively long. It opens apically into the very long epiphallus . A short conical blind sack (flagellum) is formed at the transition. The epiphallus is relatively thin, with a short caecum in the middle. The actual penis is very short and swollen at the epiphallus / penis junction. The epiphallus is about three times the length of the penis. This gradually decreases in thickness towards the opening into the atrium. Shortly in front of the mouth sits the very long penile appendix, with a comparatively very short and thick lower part (A-1), a spherically swollen part (A-2), a moderately long part with less thickness (A-3), a very thin middle part (A-4) and a club-shaped thickened end part (A-5). In the female genital tract, the free fallopian tube is very long and the vagina is very short. The stem of the spermathec is quite short, the small bladder comes to rest at about the lower end of the prostate. A moderately long diverticulum branches off just before the comparatively small bladder .
Similar species
The two types of Merdigera cannot be distinguished by the housing. However, there are significant differences in the anatomy of the genital apparatus. However, they cannot be confused in the terrain, as the two distribution areas are mutually exclusive.
The shell of the small wolverine snail is similar to the shell of the mountain wolverine snail ( Ena montana ), but it is significantly smaller. It also needs less moisture than this species.
Geographical distribution and habitat
The distribution area of the small wolverine snail stretches from northwest Africa over large parts of Europe to western Asia (Uzbekistan). In the north it extends to Ireland, Scotland and southern Finland and further to the east to the region around Moscow.
The small wolverine snail is rock indifferent and inhabits moderately moist, open habitats such as rows of hedges, walls and rocks, but also more shady locations such as deciduous forests. It is hidden there in wall and rock crevices, under dead wood, stones and leaves. In rainy weather, it crawls around and climbs up trees. In the Alps it rises up to 2200 m above sea level, in Bulgaria up to 2000 m.
Way of life
The 12 to 20 slightly elongated eggs (1.3 × 1.5 mm) are laid individually between May and October. The young hatch after about two weeks. The animals become sexually mature in the second year. The young animals in particular glue their housing to camouflage with a slime film made of earth and droppings. The animals are therefore very difficult to see on stones and wood. When crawling, the case is carried in a very upright position, inclined only slightly to the right.
Taxonomy
The taxon was first described by Otto Friedrich Müller in 1774 as the helix obscura . It is the type species of the genus Merdigera Held, 1838.
Danger
The species is widespread and common, but it is never found in large numbers. The species is not endangered in Germany.
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 .
- Rosina Fechter and Gerhard Falkner: molluscs. Mosaik-Verlag, Munich 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3 .
- Alexandru V. Grossu: Gastropoda Romaniae 2 Subclasa Pulmonata I Ordo Basommatophora II Ordo Stylommatophora Suprafamiliile: Succinacea, Cochlicopacea, Pupillacea. Bucharest 1987 (pp. 344-346).
- Jürgen H. Jungbluth and Dietrich von Knorre: Common names of land and freshwater mollusks in Germany (Gastropoda et Bivalvia). Mollusca, 26 (1): pp. 105-156, Dresden 2008 ISSN 1864-5127 PDF
- Michael P. Kerney, Robert AD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. Paul Parey, Hamburg & Berlin 1983, ISBN 3-490-17918-8 .
Individual evidence
- ↑ a b Vollrath Wiese: The land snails of Germany. Quelle & Meyer, Wiebelsheim 2014 ISBN 978-3-494-01551-4 (p. 115/116)
- ^ Anatolij A. Schileyko: Treatise on Recent Terrestrial Pulmonate Molluscs. Part 2. Gastrocoptidae, Hypselostomatidae, Vertiginidae, Truncatellinidae, Pachnodidae, Enidae, Sagdidae. Ruthenica, Supplement 2 (2): pp. 129-261, Moscow 1998 ISSN 0136-0027
- ↑ Otto Friedrich Müller: Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volume alterum. S. I-XXXVI, (1-214), Copenhagen & Leipzig, Heineck & Faber, 1774 Online at www.biodiversitylibrary.com (p. 101).
