Swabian grass snail
| Swabian grass snail | ||||||||||||
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Vallonia suevica |
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| Scientific name | ||||||||||||
| Vallonia suevica | ||||||||||||
| Geyer , 1908 |
The Swabian grass snail ( Vallonia suevica ) is a species of land living snail from the family of grass snails (Valloniidae); the family belongs to the subordination of land snails (Stylommatophora).
features
The disk-shaped shell of the Swabian grass snail is 1.2 to 1.5 mm high and 2.1 to 2.7 mm wide. It has 2 7/8 to 3 3/8 turns, 1 1/8 of which are on the embryonic housing. The turns increase rapidly and regularly and are well rounded on the periphery. Seen in cross-section, however, they embrace only a little. The last passage descends in the last quarter or eighth towards the mouth, often even below the periphery of the previous passage. The seams between the turns are comparatively deep. The umbilicus is wide open and takes up about 3/10 the diameter of the case. The mouth plane is very oblique to the coil axis. The mouth is rounded, the points of attachment to the previous passage are very close. They are connected by a thin, transparent callus, which is curved towards the inside of the mouth. The edge of the mouth is gradually bent outwards. The edge of the mouth itself is thin and fragile. Inside it is reinforced by a thick and wide, threshold-like lip, which is set off from the actual edge by a wide ring-shaped groove. However, it does not protrude above the level of the mouth.
The embryonic housing shows only very indistinct and very fine spiral stripes. The Teleoconch usually only has fine and regular growth strips. Only occasionally are they coarser and more irregular. Two or three ribs may also appear just before the mouth. The spaces between the ribs are closely striped. The shell is translucent, glossy and slightly yellowish or brownish in color.
Similar species
The Swabian grass snail is similar to the ribbed grass snail ( Vallonia costata ) in size, shell shape and mouth shape, the latter is ribbed.
Geographical distribution and habitat
The original distribution area had its focus in river valleys in southern Germany (Neckar, Ammer, Kocher, Tauber and Nagold) as well as in the upper Danube valley and the valleys of the Swabian Alb. But there are also isolated occurrences in the Bavarian Alpine foothills, in Rhineland-Palatinate (Moselle and Sauer area), North Rhine-Westphalia and in Lower Austria. Surprisingly, it was also found near Arco in the Sarca Valley north of Lake Garda. It may have already died out in Austria.
It lives in the area of distribution on moderately dry and moist meadows in the river plains, in southern Germany mostly sage and oat meadows (Arrhenateretum salvietosum), with real clover ( Anthyllis vulneraria ), upright trespe ( Bromus erectus ), meadow sage ( Salvia pratensis ), small weasenkopf ( Sanguisorba minor ) and scabiosa knapweed ( Centaurea scabiosa ), which are extensively farmed. It was therefore often found in river genists.
Taxonomy
The taxon was established by David Geyer in 1908. It has always been recognized as a valid species ever since. The second "Swabian" species of the genus Vallonia , the Alamannic grass snail ( Vallonia alamannica ) is partly regarded as a synonym for Vallonia suevica , but partly also (again) recognized as an independent species. Especially Wolfgang Rähle (1939-2019), the (likely) the self emphasizes that taxon.
Danger
The Swabian grass snail is threatened with extinction in Germany. In Baden-Württemberg it is currently still classified as “only” endangered, in Bavaria, however, it is threatened with extinction. In Austria it is probably already extinct. The IUCN also classifies the species as endangered.
The main reasons for the rapid decline in populations are the measures to regulate the river, to protect against floods and to convert the poorly digested, non-fertilized sage and oat meadows into intensively used arable land or into heavily fertilized and often mowed intensive farm meadows.
supporting documents
literature
- Jochen Gerber: Revision of the genus Vallonia Risso 1826 (Mollusca: Gastropoda: Valloniidae). Schriften zur Malakozoologie, 8: 1-227, Cismar, 1996 (pp. 169–176)
- Michael P. Kerney, Robert AD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg & Berlin 1983, ISBN 3-490-17918-8 (p. 126)
- 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., Planet Poster Ed., Göttingen 2012, ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (S. 207) (im Following, Welter-Schultes, identification book, with corresponding page number)
Individual evidence
- ↑ Mollusks in and around Rhineland-Palatinate: Vallonia suevica (Swabian grass snail) ( Memento of the original from July 26, 2014 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ H. Kobialka, Karl-Heinz Beckmann, E. Schröder: Work checklist Mollusken NRW 6th updated edition (status: January 15, 2006). 11 pages. Unpublished manuscript. Höxter, Ascheberg-Herbern and Bonn PDF .
- ↑ a b c Welter-Schultes, Identification Book, p. 207.
- ^ Dietrich Geyer: Contributions to the mollusc fauna of Swabia II. Vallonia. Annual books of the Association for Patriotic Natural History in Württemberg, 64: 305–330, Stuttgart 1908. Online at www.biodiversitylibrary.org (pp. 324–325)
- ↑ a b Fauna Europaea
- ↑ a b Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 (pp. 94/5)
- ↑ Wolfgang Rähle: Notable Vallonien discoveries in the nature reserve "value fields" in Horb am Neckar (Freudenstadt district, Baden-Wuerttemberg). Announcements of the German Malacoological Society, 86: 1-5, Frankfurt / M. PDF ( Memento of the original from July 25, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Manfred Colling, Gerhard Falkner, Klaus Groh,; Jürgen H. Jungbluth, Matthias Klemm, Hans-Jörg Niederhöfer, Wolfgang Rähle, Günter Schmid: Red list and list of species of snails and mussels in Baden-Württemberg. State Institute for the Environment, Measurements and Nature Conservation Baden-Württemberg PDF
- ^ Bavarian State Ministry for the Environment, Health and Consumer Protection; Red list of endangered animals and vascular plants in Bavaria. Abstract, 186 pp., Munich 2005 PDF (p. 147)
- ↑ Vallonia suevica in the Red List of Threatened Species of the IUCN 2013. Posted by: Falkner, M., von Proschwitz, T. & Rüetschi, J., 2010. Accessed July 15, 2014.
