Wide-mouthed glass snail

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Wide-mouthed glass snail
Wide mouthed glass snail (Semilimax semilimax)

Wide mouthed glass snail ( Semilimax semilimax )

Systematics
Subordination : Land snails (Stylommatophora)
Superfamily : Limacoidea
Family : Glass snails (Vitrinidae)
Subfamily : Vitrininae
Genre : Semimilax
Type : Wide-mouthed glass snail
Scientific name
Semilimax semilimax
( J. Férussac , 1802)

The wide mouthed glass snail ( Semilimax semilimax ) is a "half- nudibranch " from the family of glass snails (Vitrinidae), which is counted among the land snails (Stylommatophora). The animals can no longer completely withdraw into the small housing.

features

The right-hand wound case is very flat with a very crooked muzzle. The thread can hardly be seen in the side view. The body can no longer be withdrawn into the housing. It has a width of 4 to 5 mm. The case has 1.75 turns increasing very rapidly. The end turn is very much widened and takes up almost 75% of the total diameter in the apical view. The very crooked turn, the very flat thread and the strong widening of the end turn result in an elongated, ear-shaped overall habit.

The skin seam at the base of the mouth is very wide, but it narrows from the spindle to the outer edge and fades out. The upper edge of the mouth up to the approach to the previous turn is straight to slightly concave. A navel is not developed. The edge of the spindle extends so far around the housing axis that all the windings are visible through the skin seam.

The shell is very thin and fragile. It is translucent and slightly green in color. With the living animal, however, the shell looks slightly horn-colored or even slightly reddish. The surface is very finely striped and high-gloss. The protoconch has small dimples arranged in spiral rows.

The soft body is dark gray on the back and becomes lighter on the sides. When stretched out, the animal measures 12 to 15 mm. The coat is very large and covers almost the entire back down to the neck and even a little on the sides. The mantle lobe, on the other hand, is relatively narrow, it extends to the apex and covers it. The radula is dichoglossal.

In the hermaphroditic genitalia, the protein gland (albumin gland) is clustered, not compact. The egg ladder (spermoviduct) is long and slender. The free fallopian tube is very short, but the vagina is much longer. The spermathec has a short stalk and a spherical to elongated bladder.

The spermatic duct (vas deferens) is short and winding and penetrates the penis apically. The penis is short and baggy. One retractor muscle is missing. The blind sac-like sarcobelum is about three to four times as long as the penis. The apical part of the penis is glandular, the lower part is surrounded by a tissue covering. There is a pilaster-like structure inside the penis. The penis, sarcobelum and vagina flow into the long, muscular atrium at roughly the same height.

The sarcobelum or copulation arm consists of a front papilla and a long, fold-out, tube-like part. This ends on the inside with a thorn-like structure with a thin conchin coating which, after the protuberance, lies at the tip of the mating arm.

Distribution of the species (according to Welter-Schultes, 2012)

Geographical distribution and habitat

The distribution area extends in Germany to the northern low mountain ranges, in the west to the Rhine, in the south to the Alps (Switzerland, Austria, northern Italy, Slovenia; the western border runs through eastern Switzerland), in the east to the Czech Republic, Southern Poland, Slovakia, Hungary, Northern Croatia, Western Ukraine and Romania. An isolated occurrence was also found west of the Rhine in Alsace.

The species prefers moist, shady locations in ravines and mountain forests under stones and litter. But it also occurs above the tree line in open habitats that are exposed to high levels of precipitation; in Switzerland up to 1800 m above sea level.

Way of life

The species has an annual cycle. Copulation and the subsequent oviposition take place between October and January. In about 6 to 9 clutches, 50 to 90 egg-shaped eggs (1–1.5 mm long) are laid in moist moss. The young hatch after 3 to 8 weeks and become sexually mature after 4 to 6 months. The animals die between April and June; they reach an age of 12 to 14 months.

During copulation, the two partners suck on each other with the everted copulation arm. The penises are inserted into each other's atria, where the sperm transfer takes place.

Taxonomy

The taxon was first described in 1802 by Jean Baptiste Louis d'Audebert de Férussac as Helix semilimax . Type locality is Billafingen . The taxon is generally recognized and is the type species of the genus Semilimax Stabile, 1859.

Danger

The species is considered endangered in Germany. In the opinion of the IUCN, however, the species is not endangered across the entire range .

literature

  • Rosina Fechter and Gerhard Falkner: molluscs. 287 pp., Munich, Mosaik-Verlag 1990 (Steinbach's Nature Guide 10) ISBN 3-570-03414-3 , p. 172
  • Michael P. Kerney, RAD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg, p. 152.

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. 124.
  2. ↑ Lothar Forcart: Monograph of the Swiss Vitrinidae (Moll. Pulm.). Revue Suisee des Zoologie, 51: 629-678, 1944 Online at Biodiversity Heritage Library , pp. 664-666.
  3. ↑ Folco Giusti, Viviana Fiorentino, Andrea Benocci, Giuseppe Manganelli: A Survey of Vitrinid Land Snails (Gastropoda: Pulmonata: Limacoidea). Malacologia, 53 (2): 279-363, 2011 Academia.edu , pp. 344/45.
  4. ↑ Anatolij A. Schileyko: Treatise on Recent Terrestrial Pulmonate Molluscs Part 11 Trigonochlamydidae, Papillodermidae, Vitrinidae, Limacidae, Bielziidae, Agriolimacidae, Boettgerillidae, Camaenidae. Ruthenica, Supplement 2 (11): 1467-1626, Moscow 2003 ISSN  0136-0027 , p. 1484.
  5. ^ 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., Planet Poster Ed., Göttingen 2012, ISBN 3-933922-75-5 , ISBN 978-3-933922-75-5 (p. 429)
  6. ^ Ewald Frömming: Biology of the Central European Landgastropods. 404 S., Duncker & Humblot, Berlin, 1954, pp. 117-119.
  7. ↑ a b Jean Baptiste Louis d'Audebert de Férussac: About a new species of animal that unites the genera Limax and Helix, Helix Semilimax. Der Naturforscher 29: 236-241, Halle, 1802 Digital Collections Bielefeld University .
  8. ↑ AnimalBase: Semilimax semilimax (J. Ferussac, 1802)
  9. ↑ Fauna Europaea: Semilimax semilimax (J. Ferussac, 1802)
  10. ↑ MolluscaBase: Semilimax semilimax (J. Férussac, 1802)
  11. ↑ a b Vollrath Wiese: The land snails of Germany. 352 pp., Quelle & Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 (p. 232).
  12. ↑ The IUCN Red List of Threatened Species: Semilimax semilimax