Anisus calculiformis
Enggewundene plate screw
The Enggewundene plate screw ( Anisus calculiformis ) ( under Anisus semptemgyratus formerly often wrongly ) is a water lung worm ( Basommatophora ) from the family of the plate screw ( Planorbidae ).
Features
The housing is very flat disc-shaped and enggewunden. It measures 6-7 mm in diameter, is about 1 mm high and has 7.5 to 8 turns, which are only increasing slowly and regularly. The surface is finely striated and horn brown. In the last turn of the handle at the top is rounded obtuse, rounded uniformly at the bottom. The mouth is oval and slightly crooked. The mouth is closed by a calcareous septum in dry traps.
Life, the occurrence and distribution
The species lives in ponds, pools and swamps and endures prolonged dry traps. The species is widespread in Eastern Europe. In the north, the westernmost occurrence sufficient to Mecklenburg in the south reaches the westernmost area of distribution to the Po Valley.
Similar Species
The species forms from to 8 whorls, significantly more than any other Anisus species.
Endangering
The species is endangered in Germany and is on the red list. Also, in some Eastern European countries, it is very rare and threatened.
System
The genus Anisus is a part of the authors divided into two subgenera. Anisus ( Anisus ) Studer, 1820 and Anisus ( Disculifer ) C. Boettger, 1944 In this subgenus Outline Anisus calculiformis is placed in the Nominatuntergattung Anisus. The enggewundene plate screw was formerly usually referred to as Anisus septemgyratus Rossmaessler, 1835. In the examination of animals from the type locality ( Adige in Bolzano ), however, it turned out that these were identical with Anisus leucostoma. Anisus septemgyratus Rossmaessler 1835 is therefore a junior synonym of Anisus leucostoma Millet, 1813 In the literature the name Anisus septemgyratus but was misinterpreted and applied to Anisus calculiformis ( Sandberger, 1875). ; Anisus septemgyratus auct. must therefore be denoted by Anisus calculiformis ( Sandberger, 1875).