Pupilla sterrii is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of minute air-breathing land snail

Land snail

A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells, It is not always an easy matter to say which species are terrestrial, because some are more or less...

, a terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 pulmonate gastropod mollusk or micromollusk

Micromollusk

A micromollusk is a descriptive term for a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also reach adult size at very small...

 in the family Pupillidae

Pupillidae

Pupillidae is a family of mostly minute, air-breathing, land snails, terrestrial pulmonate gastropod mollusks or micromollusks in the clade Stylommatophora....

.

Distribution

This species has scattered distribution and occurs in countries including Eurasia: Alps and Carpathians to Turkey and NW China

• endangered in Germany
• lower concern in Austria
• lower concern in Switzerland
• Italy
• vulnerable in the Czech Republic
• Slovakia
• Poland

In lower altitudes threatened by continuous habitat destruction

Habitat destruction

Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

s.

Description

The shell

Gastropod shell

The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 is light horny coloured, weathering grey, finely ribbed. Whorls

Whorl (mollusc)

A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...

 are strongly convex with deep suture. The aperture

Aperture (mollusc)

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....

 is with 2 teeth.

The height of the shell is 2.8-3.5 mm. The width of the shell is 1.6 mm.

Ecology

Pupilla sterrii occur in grass of very dry and sunny limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 rocks, between stones, on dry meadow

Meadow

A meadow is a field vegetated primarily by grass and other non-woody plants . The term is from Old English mædwe. In agriculture a meadow is grassland which is not grazed by domestic livestock but rather allowed to grow unchecked in order to make hay...

s on calcareous substrate. In north Italy up to 2800 m.

Ovoviviparous.