Schmidt's dwarf snail
| Schmidt's dwarf snail | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sadleriana schmidtii from Slovenia |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Sadleriana schmidtii | ||||||||||||
| ( Menke , 1850) |
Schmidt's dwarf snail ( Sadleriana schmidtii ) is a rare species of the genus dwarf snail ( Sadleriana ) from the family of water snail (Hydrobiidae).
features
The very small, right-hand wound case is approx. 3.2 mm high and 3 mm wide and almost spherical in shape. The last deal increases very strongly. The mouth is egg-shaped and rounded at the top. The mouth edge is thin and hardly thickened. Only the edge of the spindle is slightly thicker. At the top it is a little different from the previous deal. The navel is wide open and very deep. The case itself is brown. It is often covered with a green coating of algae, especially when it is found in a bright environment.
distribution and habitat
Schmidt's dwarf snail ( Sadleriana schmidtii ) occurs according to current knowledge in caves, springs and streams in Slovenia , Croatia and Bosnia-Herzegovina .
Dwarf snails live almost exclusively in cold streams or rivers and are so-called pointer species for pure water. They need largely constant temperatures in their habitat and feed on algae and bacteria films that graze on the surface of stones in the water.
Way of life
Schmidt's dwarf snail is highly specialized and therefore very well adapted to the nutrient-poor habitat. Due to the low ecological amplitude, it reacts to changes in its habitat within a short period of time with a decreasing number of individuals or even local extinction. It is spread by larger animals, on which snails or their eggs are transported from one body of water to the next.
Taxonomy
The species was set up in 1849 by Karl Theodor Menke as Valvata Schmidtii . In the subsequent literature it often appears in the spelling schmidti , which is to be assessed as an incorrect secondary spelling. The Fauna Europaea recognizes the taxon as valid.
The type locality is near Sušica, near Novo mesto in Slovenia. According to Bole & Velkovrh (1986) and Radoman (1985), many older reports from Slovenia, Croatia and Bosnia-Herzegovina do not refer to this species, which according to these information only occurs in a small area in south-east Slovenia and the immediately adjacent Croatia. Further research is required to clarify this.
The pygmy snails can only be anatomically determined with certainty on the basis of the sexual organs . Also sequencing of DNA must often be used. Older information based on empty shells can therefore be problematic, as some species are very similar to one another.
Danger
Dwarf snails are endangered by water barriers and water use (especially in dry regions where excessive water use in summer causes many brooks to dry out) as well as construction work in the vicinity of the water body. Entry of nitrogen from the air, from sewage or from adjacent agricultural areas lead to eutrophication . In particular, the occurrences in caves are difficult to access, the actual population sizes and their condition or damage from sewage etc. are therefore largely unknown.
The IUCN currently classifies Sadleriana schmidtii as "Least Concern" due to the assumed wide distribution area. Should further investigations confirm that the species only occurs in a very small area, the endangerment assessment would have to be revised.
supporting documents
literature
- Stephan Clessin: The mollusc fauna of Central Europe. 2. The mollusc fauna of Austria-Hungary and Switzerland. II + 860 S., Bauer & Raspe, Nuremberg, 1887. Online at www.biodiversity.org (p. 664, genus Sadleriana )
- J. Bole, F. Velkovrh: Mollusca from continental subterranean aquatic habits . In: Botosaneanu, V .: Stygofauna mundi : 177-208; Leiden 1986.
- Pavle Radoman: Hydrobioidea a Superfamily of Prosobranchia (Gastropoda) I Systematics. Serbian Academy of Sciences and Arts, Monographs, 547: 256 pp., Belgrade 1983.
- Pavle Radoman: Hydrobioidea, a superfamily of Prosobranchia (Gastropoda) II. Origin, zoogeography, evolution in the Balkans and Asia Minor . Monographs, Institute of Zoology (Faculty of Science) 1 (1): 1-173. Beograd 1985.
Individual evidence
- ^ Karl Theodor Menke: Literature. Zeitschrift für Malakozoologie, 6: p. 161–167, Frankfurt / M., 1850 Online at www.biodiversitylibrary.org (p. 166/7)
- ↑ Fauna Europaea: Sadleriana schmidtii (Menke 1849)
- ↑ Sadleriana schmidtii in the IUCN Red List of Threatened Species 2012.2. Posted by: Seddon, M. & Slapnik, R., 2010. Retrieved January 23, 2013.