Ribbed grass snail
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Ribbed grass snail ( Vallonia costata ) |
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| Vallonia costata | ||||||||||||
| ( OV Müller , 1774) |
The finned grass snail ( Vallonia costata ) 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 almost disc-shaped case is about 1.1 to 1.6 mm high and 2.2 to 2.7 mm wide. The thread rises very little from the plane. There are up to 3 ¼ turns that are lightly shouldered; the periphery is slightly above the center of the turns. The embryonic housing takes 1 1/8 turns. The turns initially increase rapidly and regularly. The last turn descends from the turn axis and increases strongly, almost like a funnel. The passageways are strongly arched, but when viewed in cross-section, they encompass only a little. The navel is very wide open, almost bowl-shaped. The mostly round mouth is very crooked to the spiral axis. The points of attachment of the mouth seam to the previous turn are brought closer to one another and connected to one another by a thin callus. The edge of the mouth is strongly curved and forms a strong, white, brim-like lip, which is separated from the sharp edge of the mouth by a wide groove. The embryonic casing usually shows clear spiral lines, but these are almost exclusively limited to the peristracum. The surface of the Teleoconch has regularly arranged and quite sharp ribs. In addition to the ribs, there are also fine, often irregular strips of growth. The ribs have a high proportion of organic periostracum . In the case of heavily weathered housings in which the periostracum is already missing or organically degraded, the ribs are therefore difficult to see. The housing is gray-white, yellowish to brownish-gray. The case wall is thin to medium thick, the shell is a little translucent. The lip shines through as a wide white stripe around the mouth. The radula has 29 elements per transverse row, a total of about 70 transverse rows.
Most of the specimens are aphallic, i.e. H. have reduced the final male exit ducts in the hermaphroditic genital apparatus. They multiply through self-fertilization. In the few specimens in which the male final exit ducts are still present (euphallic), the sperm duct (vas deferens) branches off early from the egg duct (sperm duct). It gradually merges into the epiphallus, which is slightly shorter than the penis. A very long, thin appendix with an elongated, club-shaped end branches off at the epiphallus / penis transition. The retractor muscle splits at the end and inserts on the epiphallus and appendix, each near the penis. The free fallopian tube is shorter than the vagina. The stem of the spermathec is short and thin, the bladder oblong-egg-shaped and only moderately large.
Similar species
The ribbed grass snail resembles the Swabian grass snail ( Vallonia suevica ) in shape and size of the shell. But the latter has no ribs. In the other Vallonia species, the mouth rim is not as wide and strongly curved outwards. In addition, the ribs are missing. Only Vallonia enniensis is ribbed, but finer and denser.
Geographical distribution and habitat
The finned grass snail occurs all over Europe, in Northern Europe up to about 70 ° north latitude (here only along the coasts), from the Iberian Peninsula in the west to the Russian Far East. It is very likely also found in North America. This would have a Holarctic distribution. According to Gerber (1996), however, this evidence is probably based on confusion with other ribbed Vallonia species. In the south of the distribution area it has been found in Turkey and Northwest Africa. In Central Asia, the species has been found in Iran, Afghanistan, Kashmir and Mongolia. The species is also found in the Canary Islands, Madeira and the Azores. In the Alps, it rises to 2200 m above sea level. It has also been anthropogenic to South Africa.
It prefers moderately moist to rather dry, open habitats such as scree, stone walls, semi-arid lawns, sand dunes, rarely also in dry, light forests, very rarely in swamps.
Way of life
Under laboratory conditions, the animals liked to eat withered leaves of the felt hornwort ( Cerastium tomentosum ) and began to lay eggs as early as the beginning of March. Only one egg was laid per day, but often for several days in a row, but also at intervals of up to four days. The egg-laying ended in March. The eggs are whitish and opaque. They are flattened, 0.5 mm wide and 0.7 to 0.8 mm long. The hatched young have a milky white color. The casing is yellowish and transparent. It is 0.47 to 0.52 mm wide and not yet ribbed. With a diameter of 0.9 to 1 mm, however, ten ribs are already formed.
Taxonomy
The taxon was first described by Otto Friedrich Müller in 1774 as Helix costata . The type locality is Frederiksdal near Copenhagen (Denmark). Today it is made consistent with the genus Vallonia Risso, 1826. Some authors also exclude two subspecies Vallonia costata costata and Vallonia costata helvetica (Sterki, 1890). However, the Fauna Europaea rejects this subspecies.
Danger
The species is not endangered in Germany.
supporting documents
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 , (p. 138).
- Rosina Fechter and Gerhard Falkner: molluscs. 287 pp., Mosaik-Verlag, Munich 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3 , (p. 150).
- Jochen Gerber: Revision of the genus Vallonia Risso 1826 (Mollusca: Gastropoda: Valloniidae). Schriften zur Malakozoologie 8: 1-227, Cismar, 1996, (pp. 156-169).
- Michael P. Kerney, RAD 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. 125/6).
- 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 , (p. 206).
Individual evidence
- ^ Hugh Watson: The affinities of Pyramidula, Patulastra, Acanthinula, and Vallonia. 14: 6-30, London 1920 Online at www.biodiversitylibrary.org (p. 11)
- ↑ Alexandru V. Grossu: Gastropoda Romaniae 2 Subclasa Pulmonata I Ordo Basommatophora II Ordo Stylommatophora Suprafamiliile: Succinacea, Cochlicopacea, Pupillacea. 443 S., Bucharest 1987, (pp. 255, 258-260).
- ^ Yuri I. Kantor, Anatoly A. Schileyko, Maxim V. Vinarski, Alexander V. Sysoev: Catalog of the continental mollusks of Russia and adjacent territories. Version 1.0, February 15, 2009, PDF
- ↑ Hartwig Schütt: "Turkish land snails." 432 p., Verlag Christa Hemmen, Wiesbaden 1993 ISBN 3-925919-15-5 .
- ↑ MB Seddon, DT Holyoak: Land gastropoda of NW. Africa. New distributional data and nomenclature. Journal of Conchology, 34: 311-323, 1993 abstract
- ^ David G. Herbert: The introduced terrestrial Mollusca of South Africa. SANBI Biodiversity series, 15, South African National Biodiversity Institute, Pretoria 2010 ISBN 978-1-919976-56-3 PDF .
- ↑ Otto Friedrich Müller: Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volume alterum. SI-XXXVI, 1-214, Heineck & Faber, Copenhagen & Leipzig, 1774, online at www.biodiversitylibrary.org (p. 31)
- ↑ a b [1] Fauna Europaea: Vallonia costata (OF Müller 1774)
- ↑ Christa Frank: About gastropod communities in central Styria cave portals. Scientific reports from the Lower Austrian State Museum, 10: 191-213, Vienna 1997 PDF
- ^ Vollrath Wiese: The land snails of Germany. Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 , (p. 93/4)
