''Chilostoma achates'' is a species of medium-sized, air-breathing,

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

pulmonate Pulmonata or pulmonates is an informal group (previously an order, and before that, a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group inclu ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Helicidae Helicidae is a large, diverse family of western Palaearctic, medium to large-sized, air-breathing land snails, sometimes called the "typical snails." It includes some of the largest European land snails, several species are common in anthropoge ...

, the true snails.

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has defined the snail as

Near threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

, due to the development of tourism. The species inhabits high-altitude

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

environments in the eastern

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

, particularly in

South Tyrol South Tyrol ( , ; ; ), officially the Autonomous Province of Bolzano – South Tyrol, is an autonomous administrative division, autonomous provinces of Italy, province in northern Italy. Together with Trentino, South Tyrol forms the autonomo ...

and the

Carnic Alps The Carnic Alps (; ; ; ) are a range of the Southern Limestone Alps in Austria and northeastern Italy. They are within Austrian East Tyrol and Carinthia, and Italian Friuli (Province of Udine) and marginally in Veneto. Etymology They are ...

of northern Italy, where it grows on damp rock faces and ledges maintained by

seepage In soil mechanics, seepage is the movement of water through soil. If fluid pressures in a soil deposit are uniformly increasing with depth according to u = \rho_w g z_w, where z_w is the depth below the water table, then hydrostatic conditions wi ...

and

snowmelt In hydrology, snowmelt is surface runoff produced from melting snow. It can also be used to describe the period or season during which such runoff is produced. Water produced by snowmelt is an important part of the annual water cycle in many part ...

Taxonomy and nomenclature

''Chilostoma achates'' (Rossmässler, 1835) was first introduced as ''Helix foetens'' var. ''achates'', one of several varieties then included under a broadly defined ''H. foetens''. In 1933

Lothar Forcart Lothar Forcart, full name Lothar Hendrich Emil Wilhelm Forcart-Müller, abbreviated as Lothar H. E. W. Forcart, (1902-1990) was a zoologist, malacologist, and herpetologist from Switzerland Switzerland, officially the Swiss Confederation, ...

reclassified it as the

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

''Chilostoma zonatum achates'', before Carlo Alzona (1971) restored it to full species rank—a treatment still followed by modern checklists.

Description

The shell ranges from 17 to 29 mm across and 7 to 12 mm high. Its colour is a pale yellowish horn, usually bearing a single brown band around the periphery and a paler zone just beneath. There are five gently rounded spiral turns (

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). In nature File:Photograph and axial plane floral diagra ...

s), separated by a shallow groove called the suture. The final whorl widens markedly before the shell's opening, revealing a broad, slightly off-centre

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

(the hollow at the shell's base). The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

(opening) is set at an angle and bordered by a white lip that is turned back slightly.

Distribution and habitat

This snail occurs in the eastern

of northern Italy, with confirmed populations in

(Alto Adige) and the

. It inhabits high-altitude

environments—sheer or overhanging rock faces, narrow ledges and mixed

scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. The term ''scree'' is ap ...

—where continual

and residual

create the damp conditions it requires.

References

{{Taxonbar, from=Q14625306 Chilostoma Gastropods described in 1835