Blue snails

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Blue snails
Blue snail (Bielzia coerulans)

Blue snail ( Bielzia coerulans )

Systematics
Subordination : Land snails (Stylommatophora)
Superfamily : Limacoidea
Family : Schnegel (Limacidae)
Subfamily : Limacopsinae
Genre : Bielzia
Type : Blue snails
Scientific name of the  subfamily
Limacopsinae
Gerhardt , 1935
Scientific name of the  genus
Bielzia
Clessin , 1877
Scientific name of the  species
Bielzia coerulans
( M. Bielz , 1851)

The blue snail ( Bielzia coerulans ) is a species of nudibranch from the Carpathian Mountains from the family of snails (Limacidae) in the subordination of land snails (Stylommatophora). In 2014 at least one introduced population was confirmed in the Westerwald. With its mostly intense blue color it is a very easily recognizable, albeit very rare, species. Bielzia coerulans is the type species and currently the only species of the genus Bielzia Clessin, 1887. This genus is in turn the only genus of the subfamily Limacopsinae Gerhardt, 1935. The Subfamily name is based on the younger synonym of Bielzia , Limacopsis Simroth, 1888.

features

The body of the blue cone reaches a length of 10 to 14 cm (up to 18 cm) when stretched out. The keel is clearly formed and reaches up to the rear edge of the mantle shield. The mantle shield takes up less than ⅓ the length of the body. The skin furrows are clearly developed. On the mantle shield, 16 to 17 folds can be counted between the midline and the breathing hole. The drawing and color change with the age of the animals. Adult animals are light gray with a bluish or slightly greenish tint, blue, green-blue, malachite green, violet-black to black and have no markings. The young animals show a light brown back, the sides of the body, the keel and the head are dark yellow. In the back of the body there is a dark, sharply defined side band on each side. The coat usually has a central welt and olive-tinted sides. During sexual maturity, the color change process takes place, beginning at the tail end and progressing to the front end. The sole of the foot is uniformly blue-black or with darker side panels. The body mucus is light yellow and transparent, the sole mucus is colorless.

In the genital system, the hermaphroditic gland is round, the size depends on the age of the animal. It is light gray and compact and is often further forward than the protein gland, the size of which also depends on the animal's degree of maturity. The hermaphrodite is short and strongly twisted. The Eisamenleiter (speroviduct) is long and narrow, and somewhat thickened in the middle part. At the branching of the male and female genital ducts, the spermatic duct is slightly swollen. It's thick, meaty, and almost straight. It opens directly into the atrium, there is no penis. The inside of the spermatic duct has weak longitudinal folds. Next to the mouth of the vas deferens in the atrium sits a club-shaped organ with weak longitudinal folds on the inside. The longitudinal folds are connected to one another by zigzag-like transverse structures. A retractor muscle attaches to the side and crosses with the right antennae retractor muscle. The tubular fallopian tube is significantly longer than the spermatic duct and forms a loop. It is connected to the spermatic duct by a tissue. The seed pouch is long-oval with a short, strong stem. Three intestinal loops are formed in the digestive tract, the first of which is the largest; the other two intestinal loops are approximately the same size. The chalky bowl in the mantle is elongated-oval and measures about 10 mm in length and 5.5 mm in width.

Blue snails copulating

Similar species

Typical specimens are unmistakable due to their color.

Within the Limacidae, the blue snail is completely isolated due to its anatomy and copulation. In contrast to the other species of Limacidae, they do not transfer the sperm from penis to penis, but have a cylindrical copulatory organ, about 1.5 cm long and 3.5 mm in diameter, which is inserted into the genital opening of the other animal. It is of course also referred to as "penis" in the literature, but is not directly homologous with the penes of the other species of Limacidae. This organ keeps the animals close together when exchanging sperm. The sperm does not exit through this organ, but through the sperm duct directly next to it.

Geographical distribution and habitat

The blue snail lives mostly on the bottom of coniferous, deciduous and mixed forests in the eastern Carpathians, in southern Poland, in the eastern Czech Republic, Romania, Slovakia and the Ukraine. The species rises there up to an altitude of almost 2000 m in the subalpine and alpine vegetation level . Sightings in Germany are becoming more frequent.

Way of life

The animals hide under bark and in tree stumps during the day and only become active in the evening and at night. They don't crawl up trees, they live on the ground. They feed on mushrooms, lichens, and strawberries. In captivity, they were fed cucumber and lettuce.

Copulation and reproduction

The animals reach sexual maturity with a length of about 60 mm. They will then continue to grow until they have reached their adult size. Like all land snails, they are hermaphrodites . Mating usually takes place in June / July. Each animal mates several times. Ulrich Gerhardt described the individual phases of copulation in detail in 1934 and compared them with those of other Limax species.

If an animal ready to mate meets another individual who is ready to mate, it follows him. The pursuit only lasts a few minutes. The pursued animal turns quickly to the right. Unlike other Limax species, a circle is not formed, but the pursuer remains stretched, while the pursued animal is strongly curved. Now the heads move towards each other and the “penes” appear in the genital orifices as hump-like, initially bluish-white, then whitish humps. If the genital orifices are directly opposite each other, the penes project to a length of about 1.5 cm; they measure about 3.5 millimeters in diameter. They cross each other, but do not wrap around each other and are inserted into the sexual opening of the other partner. In the further course of copulation nothing can be seen of the genitals, the process of sperm exchange can only be inferred. The bodies are pressed tightly together and the breathing holes are wide open. The feelers are drawn in and the sole of the foot is slightly pushed forward as a bulge. The animals now lie in this position for up to 40 minutes without moving. During this time, the exchange of the sperm must take place. Then the separation of the two partners begins. The penes are quickly everted. The actual copulation takes 35 to 52 minutes.

In July and August, 30 to 94 eggs are laid in a strand of mucus in a single clutch. The animals die after laying eggs. The eggs are 4 to 5 mm long and 3 to 4 mm wide. The young animals leave the egg shell after 17 to 25 days after oviposition. The animals live to be around one year old.

Taxonomy

The taxon was first described in 1851 by Michael Bielz as Limax coerulans . In 1887 Stephan Clessin proposed the new "Sectio" Bielzia for this species (and the var. Incompta Kimakowicz, 1884) , which was quickly accepted as a genus. Limax coerulans is the type species of the genus Bielzia Clessin, 1887. Due to the anatomy that is very different from the rest of the Limacids, the status of Bielzia as an independent genus is undisputed. Most authors even separate the genus at the subfamily level, Schileyko (2003) even places the genus in an independent family Bielziidae within the Limacoidea. Ulrich Gerhardt created the (sub) family Limacopsidae for this purpose. The name is based on Limacopsis Simroth, 1888, a younger, objective synonym of Bielzia . Bielziidae / Bielziinae Likharev & Wiktor, 1980 is again a synonym of Limacopsidae Gerhardt, 1935.

Danger

In the Czech Republic the species has the status "endangered" on the red list.

supporting documents

literature

  • Fechter, Rosina & Gerhard Falkner 1990: Mollusks. 287 pp., Mosaik-Verlag, Munich, ISBN 3-570-03414-3 , (Steinbach's natural guide 10).
  • Gerhardt, Ulrich 1934: On the biology of the copulation of the Limacids. II. Communication. Journal for Morphology and Ecology of Animals, 28: 229–258, Berlin. doi : 10.1007 / BF00412991
  • Kerney, Michael P., RAD Cameron & Jürgen H. Jungbluth 1983: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg & Berlin ISBN 3-490-17918-8
  • Wiktor, Andrzej 1973: The Polish Nudibranchs. 182 pp., Monograph Fauny Polski, Polska Akademia Nauk Zakład Zoologii Systematycznej i Doświadczalnej, Warsaw & Kraków (pp. 75-77).

Individual evidence

  1. ^ Wiese, Vollrath, 1962-: The land snails of Germany: Finding - recognizing - determining . 1st edition Quelle et Meyer, Wiebelsheim 2014, ISBN 978-3-494-01551-4 .
  2. ↑ Pelbárt, J. 2000: Data to the mollusc fauna of the Carpathian Biosphere Reserve, Ukraine (Mollusca). Miscellanea Zoologica Hungarica, 13: 85-90, Budapest. PDF
  3. ↑ Lisický MJ (1991). Mollusca Slovenska . Veda, Bratislava: 1-341.
  4. ↑ Kantor Yu I., Vinarski MV, Schileyko AA Sysoev AV: Catalog of the continental mollusks of Russia and Adjacent territories . Version 2.3. (PDF; 1.9 MB), December 22, 2009.
  5. ↑ a b Frömming Ewald 1954: Biology of the Central European Landgastropods. 404 pp., Duncker & Humblot, Berlin (pp. 167-183).
  6. ↑ Gerhardt (1934: pp. 249-254)
  7. ^ Bielz, Michael 1851: Directory of the land and freshwater mollusks of Transylvania. Negotiations and communications of the Transylvanian Society for Natural Sciences in Sibiu, 2: 14-16, 55-59, 62-65, Hermannstadt / Sibiu. Online at Biodiversity Heritage Library
  8. ↑ Kimakowicz, Mauritius (Moritz) Hieronymus from 1883-84: Contribution to the mollusc fauna of Transylvania. II. Part and addendum. Negotiations and communications of the Transylvanian Society for Natural Sciences, 24: 57-116, Hermannstadt / Sibiu Online at Biodiversity Heritage Library .
  9. ^ Clessin, Stephan 1887: The mollusc fauna of Austria-Hungary and Switzerland. Pp. 1-858, Nuremberg, Bauer & Raspe. Online at Biodiversity Heritage Library (p. 47)
  10. ^ Hesse, Paul 1926: The nudibranchs of the Palaearctic region. Treatises of the Archives for Molluscology, 2 (1): 1-152, Frankfurt / M.
  11. ↑ a b Fauna Europae - Bielzia coerulans
  12. ↑ AnimalBase - Bielzia coerulans
  13. ↑ 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
  14. ↑ Web pages of Czech and Slovak malacologists, Red List of the molluscs (Mollusca) of the Czech Republic , accessed November 17, 2012

Web links

Commons : Blauschnegel  album with pictures, videos and audio files