Balea perversa
| Balea perversa | |
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| live Balea perversa | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Heterobranchia |
| Order: | Stylommatophora |
| Family: | Clausiliidae |
| Genus: | Balea |
| Species: | B. perversa
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| Binomial name | |
| Balea perversa | |
| Synonyms | |
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Balea perversa, also known as the wall snail or tree snail,[1] is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Clausiliidae, the door snails. The shell of this species is left-handed in coiling and it looks like a juvenile of a clausiliid.
Balea perversa (as its synonymous name Pupa fragilis) is the type species of the genus Balea.
Distribution[edit]
Balea perversa is widely distributed in western and central Europe east to Ukraine and westernmost Russia:[1]
- British Isles:[3] Great Britain and Ireland
- Western Europe[3]
- Switzerland – lower concern in Switzerland[3]
- Portugal[3]
- Germany – vulnerable in Germany, endangered in Bavaria [3]
- Austria – vulnerable in Austria[3]
- Czech Republic[4]
- Slovakia[4]
- on an islet near Estonia[5]
- Sicilia[3]
- Sardinia[3]
- Iceland[3]
- in Scandinavia only coastal above 62° N[3]
It was referred from Crimea,[3] but it was probably Mentissa gracilicosta.[5]
Description[edit]
The shell is small and resembles that of a juvenile clausilid. The color is pale brownish and the surface is often silky shiny. The shell often has distinct riblets. The apical whorls are cylindrical. The shell has 8-9 whorls and (unlike many clausiliids) the last whorl has the largest diameter. It is densely ribbed. The cervix is almost without keel. Apart from a rudimentary parietal fold, there are no folds in the aperture. This species has no clausilium.[3]
The width of the shell is 2.5–2.7 mm; the height of the shell is 7–10 mm.[3]
Balea perversa differs from Balea sarsii in that it is a less slender and brownish rather than yellowish shell; the first whorl increases in diameter less rapidly, and the sculpture is more prominently striated (with what are usually distinct riblets rather than coarse growth lines).[3]
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Ecology[edit]
Balea perversa lives on mosses and at the bark of trees, also near roads, at walls and rocky slopes, at rocks, less commonly in ground litter.[3] It lives often on surfaces encrusted with lichens and other epiphytes.[3] It prefers trees with rough bark.[3] It prefers shady habitats in Portugal.[3] It may tolerate non-calcareous soils.[3] In Bulgaria it lives up to 1,600 m or perhaps to 2,400 m; in Switzerland up to 2,000 m.[3]
It is easily dispersed by birds.[3]
It feeds on mosses, algae, lichens, and cyanobacteria.[3]
It is ovoviviparous, self-fertilization predominates, even in laboratories when snails are kept in pairs.[3] Animals can reach maturity after 3–4 months under favourable conditions, one adult can give birth to 10-20 juveniles per year.[3] Animals can also be active in mild winters.[3]
It is locally threatened by too thorough and too frequent restorations of old buildings, acid rains, air pollution and cutting of old trees.[3] It has largely disappeared from inside cities.[3] Remains frequent in Ireland, but many colonies in lowland England have certainly disappeared, extinct around London since the 1920s.[3]
References[edit]
This article incorporates public domain text from the reference [3]
- ^ a b c Seddon, M.B. (2017). "Balea perversa". IUCN Red List of Threatened Species. 2017: e.T171730A1330560. doi:10.2305/IUCN.UK.2017-3.RLTS.T171730A1330560.en. Retrieved 20 November 2021.
- ^ Linnaeus C. (1758). Systema naturae per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. - pp. [1-4], 1-824. Holmiæ. (Salvius). page 767.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac "Species summary for Balea perversa". AnimalBase, last modified 12 April 2011, accessed 17 April 2011.
- ^ a b (in Czech) Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). "Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]". Malacologica Bohemoslovaca, Suppl. 1: 1-37. PDF.
- ^ a b Kantor Yu I., Vinarski M. V., Schileyko A. A. & Sysoev A. V. (published online on March 2, 2010). "Catalogue of the continental mollusks of Russia and adjacent territories". Version 2.3.1.
External links[edit]
- Balea perversa at Animalbase
- Balea perversa images at Encyclopedia of Life