Anisus

Petite plate screw

Anisus is a genus of the family of the plate screw ( Planorbidae ) from the subordination of the water snails ( Basommatophora ). It is small forms with an almost planispiral rolled housing.

Features

The housing of the Anisus species are small (up to about 10 mm in width and 2 mm in height) and flat - disk-shaped, only the belly is slightly stronger than the sunk back side. The mouth is usually more or less oblique to the axis of coiling, the windings comprise only moderate to low. Take you to even moderately, and it will be formed about 4 to 8 whorls. Some species form on the first whorls or last whorls more or less distinct edges.

Life, the occurrence and distribution

The animals live in swamps, ponds and even in temporarily desiccating waters. They live on vegetable matter, and possibly also of detritus. The Palaearctic species of the genus are widespread.

System

The genus is considered by many authors in two subgenera Anisus ( Anisus ) and Anisus ( Disculifer ) C. Boettger, divided in 1944. The species occurring in Europe are:

• Enggewundene plate screw ( Anisus ( Anisus ) calculiformis ( Sandberger, 1875) )
• White Empowered plate screw ( Anisus ( Anisus ) leucostoma ( Millet, 1813) )
• Lipped plate screw ( Anisus ( Anisus ) Spirorbis (Linnaeus, 1758) )
• Anisus ( Anisus ) strauchianus ( Clessin, 1886)
• Hot plate screw ( Anisus ( Disculifer ) vortex (Linnaeus, 1758) )
• Petite plate screw ( Anisus ( Disculifer ) vorticulus ( Troschel, 1834) )