Large keel cone
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Great keel cone ( Tandonia rustica ) |
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| ( Millet , 1843) |
The large keel snail ( Tandonia rustica ), also called the large keel slug , is a nudibranch from the family of the keel slugs ( Milacidae) in the suborder of the land snails (Stylommatophora).
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features
The body of the great keel cone is 8 to 10 cm long when stretched out. In the preserved state, the body shrinks very strongly (45 × 12 mm). The color varies from whitish, cream-colored, pinkish-yellowish, yellowish-gray, brownish to slightly reddish and violet with numerous small black spots that appear particularly in the furrows between the wrinkles or are arranged in lines there. The body color becomes less intense on the sides towards the hem of the foot. The egg-shaped mantle is more broadly rounded at the back and takes up about 30 to 40% of the body length, it has a thin, dark side band and a horseshoe-shaped furrow around the rear mantle. The breathing opening in the right rear part of the mantle has a faint light border. The keel, which extends from the rear edge of the mantle to the tip of the tail, is usually a little lighter than the back. The head and antennae are sharply defined, distinctly darker than the body. The sole is uniformly yellowish-white, the secreted mucus is colorless, viscous and sticky. When the animal is irritated, the mucus is a little less tough, whitish, and opaque.
In the genital tract, the hermaphroditic gland is comparatively small, light and elongated. The long hermaphroditic duct is strongly twisted and entwined in the front part. The albumin gland is comparatively small. The long egg ladder (spermoviduct) shows strong swellings. The spermatic duct is long and thin, it opens apically into the epiphallus. The epiphallus and penis are not separated from one another by a constriction or change in thickness. The transition from the epiphallus to the penis is marked by the insertion of the penile retractor muscle. The epiphallus is about three to four times as long as the penis. The lower part of the penis is badly swollen. Inside is a heavily ornamented papilla. The spermathec is elongated with a swelling at the base and a large tapered bladder. The free fallopian tube is much longer than the vagina. The penis and vagina open into the short atrium. The tufted accessory glands are long and thin. They sit in the lower area of the vagina and open into it.
The aragonitic shell plate in the mantle is oblong-egg-shaped, approximately symmetrical in the longitudinal direction with a core protruding slightly from the plane in the rear part. It is up to 5 mm long and 3.5 mm wide.
Similar species
The large keel cone is lighter in color and more strongly contrasted by the black dots than Tandonia kusceri and Tandonia serbica .
Geographical distribution and habitat
The original distribution area was probably southern central Europe. Currently the species is expanding its range mainly to the north. It is in southern and central France, Belgium, the southern Netherlands, southern Ireland, south-east England, high areas in Germany (in the north to the Weser Uplands), Italy to the central Apennines, Switzerland, Austria, the Czech Republic, Slovakia, isolated in central Romania, Bulgaria, Poland and Hungary detected. The species is also likely to be found in North Africa ( Libya ).
The species lives in deciduous and mixed forests and on wasteland in hilly and mountainous areas with limestone rubble. It is also less common in open cultivated land such as gardens, bushes and cemeteries. In Poland, it was often found in medieval castle ruins. But there it needs a dry and warm microclimate. In Switzerland it rises to 1,800 meters above sea level, but is rarely found above 1,200 meters. The species is not necessarily bound to limestone soils, but prefers calcareous soils.
Way of life
The animals are mostly nocturnal. Occasionally they can only be observed during the day when it is raining or damp. Otherwise they hide under leaves, dead wood or under stones overgrown with moss. The species can cause damage to vegetable cultivation when multiplied in cultivated land.
The eggs are laid in three to seven clutches in a small cave in the ground in late spring and early autumn, in the Netherlands from June to September. Each clutch contains 10 to 25 (8 to 27 eggs) oval eggs with a length of 6.5 mm and a diameter of 5 mm. Depending on the temperature, the young hatch after 40-50 days, either in autumn or not until spring, when the eggs have been laid in autumn. The animals are sexually mature after 6 to 9 months. The animals can live up to three years. Each animal can have three laying periods. However, the clutches contain fewer eggs with increasing age. After the third laying period, the animals die. In total, an animal can produce 200 to 250 eggs over the three laying periods.
The animals feed mainly on fresh parts of plants and fungi, but also on rotting plant material. Occasionally worms and small snails are also eaten.
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Taxonomy
The taxon was established in 1843 as Limax rustica by Pierre-Aimé Millet . The species was previously placed in the genus Milax , but today it is uniformly in the genus Tandonia Lessona & Pollonera, 1882.
Danger
After Wiese, the species is endangered in Germany.
literature
- Rosina Fechter and Gerhard Falkner: molluscs. Mosaik, Munich 1990, ISBN 3-570-03414-3 (= Steinbach's natural guide , volume 10), p. 184.
- 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. 180.
- Harold E. Quick: British Slugs (Pulmonata, Testacellidae, Arionidae, Limacidae). Bulletin of the British Museum Natural History, Zoology, 6 (3): 103-226, 1960.
- Andrzej Wiktor: The Polish Nudibranchs. Monograph Fauny Polski, Polska Akademia Nauk Zakład Zoologii Systematycznej i Doświadczalnej, Warsaw / Kraków 1973.
- Andrzej Wiktor: The slugs of the former Yugoslavia (Gastropoda terrestria nuda - Arionidae, Milacidae, Limacidae, Agriolimacidae). Annales Zoologici 46 (1-2): 1-110, Warsaw 1996
Individual evidence
- ^ A b 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. 439)
- ↑ Jean-Louis Eulin: Tandonia rustica (Millet 1843) (Mollusca: Gastropoda), nouvelle espèce de limace pour la Vendée. Le Naturaliste Vendéen, 3: 119–120, 2003 PDF
- ↑ Ondřej Korábek, Tomáš Čejka, Lucie Juřičková: Tandonia kusceri (Pulmonata: Milacidae), a slug new for Slovakia. Malacologica Bohemoslovaca, 15: 3-8, 2016 PDF
- ↑ Achuthan Nair, Fatma F. El-Toumi, Kama! MA Eltayeb, Abdelmuhsen Abusneina, Keshab Chandra Bhuyan: Habitat, occurrence & density of the pulmonate slugs in north-east Libya Journal of African Zoology, 110: 252-256, 1996
- ^ Klaus Bogon: Landschnecken: Biology, Ecology, Biotope Protection. Natur-Verlag, Augsburg 1990, ISBN 3-89440-002-1 , p. 221/22.
- ↑ Paul-Aimé Millet: Description de plusieurs espèces nouvelles de mollusques de la France. Magasin de Zoologie (2) 5: 1-4, Paris Biodiversity Heritage Library , p. 1, plate 63
- ↑ MolluscaBase: Tandonia rustica (Millet, 1843)
- ^ Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014 ISBN 978-3-494-01551-4 (p. 201)