Spotted bowl snail

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Spotted bowl snail
Spotted bowl snail (Discus rotundatus)

Spotted bowl snail ( Discus rotundatus )

Systematics
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Punctoidea
Family : Bowl snails (Patulidae)
Genre : Discus
Type : Spotted bowl snail
Scientific name
Discus rotundatus
( OV Müller , 1774)

The spotted bowl snail ( Discus rotundatus ), also known as spotted button snail , spotted key snail or spotted discus snail, is a species of snail in the family of bowl snails (Patulidae) from the suborder of land snails (Stylommatophora).

features

The housing is very flat-conical to almost disk-shaped and measures 5.5 to 7 mm in diameter and 2.4 to 2.8 mm in height in the adult stage. The 5.5 to 6 whorls (6½) increase slowly and have a blunt-rounded clear edge on the periphery. The navel is relatively wide and deep and takes up more than a third of the total diameter. The mouth is inclined to the winding axis and is regularly elliptical in outline. The edge of the mouth is straight, sharp or only slightly blunt.

The housings are yellowish-brown in color. There are reddish-brown spots on the perimeter at more or less regular intervals. The surface is strong and regularly ribbed across. There are seldom forms with a whitish or light greenish casing, even specimens without spots.

The sexual apparatus is simply structured. The spermatic duct penetrates the penis distally, the penile retractor muscle attaches to the side of the penis, well away from the penile apex. The free fallopian tube is short and the vagina relatively loose. The sperm library is small and rounded, and has a long, thin stem. The protein gland is moderately long and finger-shaped.

In animals from Central Europe, the soft body is bluish on the upper side, the foot below the tentacles gray-white. In southern Europe, however, the animals are more blue-black.

Similar species

The keeled bowl snail ( Discus perspectivus ) is much more clearly keeled, and the umbilicus is even wider in relation to the width of the shell. In addition, the housing of this type is even flatter. The brown bowl snail ( Discus ruderatus ) has significantly fewer turns with 4 to 4½ turns, the mouth is rounded, and the pattern of spots is missing.

Distribution area of ​​the species (in Europe)

Geographical distribution and habitat

The spotted bowl snail occurs in almost all of Europe. In Scandinavia it is restricted to the south and the coastal areas. In Finland, too, the species is restricted to the coastal areas of the extreme south. It is missing in the extreme south of the Iberian Peninsula. It is also found on the Mid-Atlantic Islands. In 2003 a record was also published in Turkey. Evidence is explained by human procrastination. It also occurs in the Crimea. There is already evidence of the species from the USA and Canada that can safely be traced back to trafficking.

The spotted bowl snail lives in damp, shady and protected places in the forest, under litter, dead wood or stones, but also in gardens, walls, cemeteries, rubbish heaps and meadows, even in caves. In Switzerland it was found at altitudes up to 2700 m. The animals feed on humus, mushrooms, algae, but also on fresh plants and, more rarely, carrion (dead insects). The species is rock indifferent.

Taxonomy

The species was first described as Helix rotundata in 1774 by the Danish mollusk researcher Otto Friedrich Müller . There are some synonyms : Helix abietina Bourguignat, 1864, Patula azorica Mousson, 1858 and Helix machadoi Milne-Edwards, 1885. The spotted bowl snail is also classified by some authors as a subgenus Discus (Gonyodiscus) Fitzinger, 1833. The two sub-genera differ in details in the genital apparatus. In the discus , the spermatic duct penetrates the penis distally, the penile retractor muscle attaches to the side of the penis. In Discus (Gonyodiscus) it is the other way round, the spermatic duct penetrates the penis laterally, and the penile retractor muscle attaches distally.

The Fauna Europaea also divides the taxon into two subspecies:

  • Discus rotundatus subsp. rotundatus (OF Müller, 1774) (the nominate subspecies)
  • Discus rotundatus subsp. omalisma (Fagot, 1879) (orig. binomials: Helix omalisma ), the Global Biodiversity Information Facility leads with
  • Discus rotundatus subsp. abietina (Bourguignat, 1864)

a third subspecies.

Wiese (2014) and Welter-Schultes (2012) neither use the sub-genus classification nor the subspecies.

Danger

The species is considered to be harmless in Germany. The populations are also stable and not endangered in the entire distribution area.

literature

  • 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 .
  • Ewald Frömming: Biology of the Central European Landgastropods. 404 p., Duncker & Humblot, Berlin 1954.

Individual evidence

  1. ↑ Jürgen H. Jungbluth and Dietrich von Knorre: Trivial names of land and freshwater mollusks in Germany (Gastropoda et Bivalvia). Mollusca, 26 (1): 105-156, Dresden 2008 ISSN  1864-5127 , p. 121.
  2. ↑ Klaus Bogon: Landschnecken biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 , p. 157/58.
  3. ^ A b Václav Pfleger: Mollusks. Artia, Prague, 1984, p. 76.
  4. ^ Alexandru V. Grossu: Gastropoda Romaniae 4 Ordo Stylommatophora Suprafam: Arionacea, Zonitacea, Ariophantacea şi Helicacea. 564 S., Bucharest 1983, pp. 33-35.
  5. ↑ Aydin Örstan: The first record of Discus rotundatus from Turkey. Triton (Journal of the Israel Malacological Society), 7:27, Rehovot 2003. (PDF) ( Memento of the original from May 11, 2008 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. @1@ 2Template: Webachiv / IABot / home.earthlink.net
  6. ^ A b Robert G. Forsyth, RG Land Snails of British Columbia. Royal BC Museum Handbook Royal British Columbia Museum, Victoria. 188 + [8] S., 2004
  7. ↑ Aydin Örstan: The first record of the European country snail Discus rotundatus (Müller, 1774) from Montreal, Canada (Discidae: Pulmonata Checklist 8 (3):. 537-539, 2012 PDF
  8. ^ Robert G. Forsyth, P. Williston: Terrestrial snails from an urban park in Vancouver, British Columbia. The Festivus, 44 (7): 77-80, 2012. PDF
  9. ↑ Otto Friedrich Müller, Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volume alterum. S. I-XXXVI (= 1-36), pp. 1-214. Havniae / Copenhagen & Lipsiae / Leipzig. Heineck & Faber, 1774 Online at www.biodiversitylibrary.org , p. 29/30.
  10. ^ Molluscs of Central Europe
  11. ↑ a b Fauna Europaea
  12. ↑ Tomas Uminski: Revision of the Palearctic forms of the genus Discus FITZINGER, 1833 (Gastropoda, endodontidae). Annales Zoologici, 20 (16): 299-329, 1962 PDF
  13. ^ Paul Fagot: Mollusques quaternaires des environs de Toulouse et de Villefranche. Bulletin de la Societé d'Histoire naturelle Toulouse, 13: 282-304, 1879 Online at www.biodiversitylibrary.org , p. 289.
  14. ↑ Global Biodiversity Information Facility (BGIF): Discus rotundatus subsp. abietina (Bourguignat, 1864)
  15. ↑ 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 (S. 215)
  16. ↑ a b Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 (p. 162)
  17. ^ AnimalBase
  18. ↑ The IUCN Red List of Threatened Species: Discus rotundatus