Widely bifurcated crystal snail

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Widely bifurcated crystal snail
Widely knotted crystal snail (Vitrea contracta)

Widely knotted crystal snail ( Vitrea contracta )

Systematics
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Gastrodontoidea
Family : Crystal snails (Pristilomatidae)
Genre : Vitrea
Type : Widely bifurcated crystal snail
Scientific name
Vitrea contracta
( Westerlund , 1871)

The wide-barked crystal snail ( Vitrea contracta ) is a land living snail - a species of the crystal snail (Pristilomatidae) in the suborder of the land snail (Stylommatophora).

features

The right-hand wound, quite small case is strongly flattened-conical, almost thick-disk-shaped. In the adult state, the housing measures 1.8 to 3.0 (usually around 2 mm) in width (diameter) and 1.0 to 1.4 mm in height. In the side view, the thread is only slightly raised. There are 4 to 5 adult turns that increase slowly and regularly. The last turn is comparatively narrow. Seen from above, it is only 1.4 to 1.6 times the previous turn. The top of the windings is flat, so the seams are very flat. The periphery is well rounded, the underside relatively flat. The mouth would be flattened-elliptical in its complete outline, oblique-crescent-shaped due to the deep cut of the previous turn. The edge of the mouth is straight and sharp, not thickened by a lip. The navel is deep and wide and widens with the last turn. All passages are visible in the navel.

The skin is colorless and translucent to slightly milky. The surface is shiny. There are very fine, irregular growth stripes and some hint of spiral lines.

In the hermaphroditic genitalia, the spermatic duct is quite short. It penetrates the penis apically through a simple pore. The penis is slim and fusiform. The penile retractor muscle attaches apically to the penis. The free fallopian tube is very short, the vagina relatively long, about as long as the penis. The distal part of the vagina is surrounded by a weak perivaginal gland. The spermathec is reduced to a finger-shaped, small process or is even absent entirely. The atrium into which the penis and vagina open is comparatively long.

Similar species

The shell of the widely-napped crystal snail is slightly less thick (high) than that of the common crystal snail ( Vitrea crystallina ), and on average slightly smaller. The last turn is narrower and the underside is flatter. The navel is a little wider and not eccentric. The mouth seam not thickened. In contrast to the common crystal snail, however, the widely-bifurcated crystal snail prefers somewhat drier and more calcareous biotopes. But it also tolerates somewhat more humid habitats. Therefore, both types occasionally appear together. The Ungenabelte crystal screw ( Vitrea diaphana ) and the Enggenabelte crystal screw ( Vitrea subrimata ) differ in the closed or almost closed navel.

Distribution area de Art (according to Welter-Schultes)

Geographical distribution and habitat

The distribution area extends over large areas of western, central and southern Europe. In the north it extends to southern Scandinavia and the coastal area of ​​southern Finland. In the east to the Baltic states, Belarus, western Russia and western Ukraine. It is absent in most of central and northern Scandinavia, but occurs in Iceland. The species can also be found in Madeira and the Azores . In the east the distribution extends to Asia Minor, the Caucasus region, the Middle East (Israel) and Cyprus. In the south the distribution area extends to North Africa. The species is also widespread in Germany, but more locally than the common crystal snail. In Switzerland it rises up to 1400 m, in Bulgaria up to 1600 m above sea level. The species is anthropogenic to other parts of the world, such as B. to British Columbia and Washington .

The animals live very hidden in the litter, in loose soil, at the foot of rocks or between scree, on meadows with scree, forests with rocks and scree, but also in cool ravines and swampy alder quarries, even in holes and crevices. In protected biotopes, they remain active even in winter. The species occurs in moist to dry habitats on calcareous soils.

Taxonomy

The taxon was established in 1871 by Carl Agardh Westerlund in the original form Zonites (Vitrea) crystallina contracta . It is now generally recognized as a valid species and is placed in the genus Vitrea . Vitrea zakynthia (P. Hesse, 1882) is treated by some authors as a subspecies of Vitrea contracta . In contrast, the fauna Europaea and the MolluscaBase Vitrea zakynthia as an independent species. Welter-Schultes writes, however, that they are interconnected by intermediate forms, so that zakinthia can not be an independent species.

Danger

In Scandinavia, stocks have fallen sharply due to acid rain. The species is threatened with extinction in Switzerland and Bavaria. The species is endangered in Rhineland-Palatinate and Austria. In Germany as a whole, however, the species is not endangered. In some places it is even extremely common. The species is even very common in Greece. The IUCN does not rate the species.

literature

  • Klaus Bogon: Land snails biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 , p. 190/91.
  • MP Kerney, RAD Cameron, Jürgen H. Jungbluth: The land snails of Northern and Central Europe . Parey-Verlag, Hamburg and Berlin 1983, 384 pp., ISBN 3-490-17918-8 , p. 163

Individual evidence

  1. ↑ Jürgen H. Jungbluth, Dietrich von Knorre: Trivial names of land and fresh water mollusks in Germany (Gastropoda et Bivalvia). Mollusca, 26 (1): 105-156, Dresden 2008 ISSN  1864-5127 , p. 122.
  2. ^ Adolf Riedel: Revision of the zonitides of Poland (Gastropoda). Annales Zoologici, 16 (23): 362-464, Posen 1957 PDF , pp. 429-430.
  3. ↑ Adolf Riedel: Zonitidae (excl. Daudebardiinae) of the Caucasus countries (Gastropoda). Annales Zoologici, 24 (1): 2-303, Posen 1966. PDF pp. 51-54.
  4. ↑ a b c d e Francisco W. Welter-Schultes: European non-marine molluscs, a guide for species identification = identification book for European land and freshwater mollusks. A1-A3 S., 679 S., Q1-Q78 S., Göttingen, Planet Poster Ed., 2012 ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (p. 359)
  5. Jump up ↑ Lothar Forcart: Vitrea contracta (Westerlund, 1873) (Zonitidae, Vitreinae) in Palestine. Argamon, Israel Journal of Malacology, 4 (1): 7-8, 1973.
  6. ^ Robert G. Forsyth: Land Snails of British Columbia. Royal BC Museum, 2004, ISBN 0774809140 , p. 175
  7. ↑ Barry Roth, Timothy A. Pearce: Vitrea contracta (Westerlund) and Other Introduced Land Mollusks in Lynnwood, Washington. The Veliger, 27 (1): 90-92, 1984 PDF (ResearchGate)
  8. ^ Carl Agardh Westerlund: Fauna molluscorum terrestrium et fluviatilium Sveciae, Norvegiae et Daniae. Sveriges, Norges och Danmarks land och sötvatten-mollusker. I. Land molluskerna. 296 pp., Bonnier, Stockholm, 1871 Online at Biodiversity Heritage Library , p. 56.
  9. ↑ Vitrea contracta (Westerlund, 1871)
  10. ↑ Fauna Europaea: Vitrea contracta (Westerlund, 1871)
  11. ^ Rosina Fechter, Gerhard Falkner: Molluscs. Mosaik-Verlag, Munich 1990 (Steinbach's Nature Guide 10), 287 pages, ISBN 3-570-03414-3 , page 174.
  12. ^ Alexandru V. Grossu: Gastropoda Romaniae 4 Ordo Stylommatophora Suprafam: Arionacea, Zonitacea, Ariophantacea şi Helicacea. 564 S., Bucharest 1983, pp. 101-102.
  13. ↑ MolluscaBase: Vitrea contracta (Westerlund, 1871)
  14. ↑ a b Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 (p. 194)