''Caseolus calvus'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of small 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 gastropod mollusks that have shells (those without shells are known as ...

terrestrial Terrestrial refers to things related to land or the planet Earth. 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 or near the ground, as opposed to ...

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 includ ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Geomitridae Geomitridae is a Taxonomy (biology), taxonomic Family (biology), family of small to medium-sized air-breathing land snails, Terrestrial molluscs, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.MolluscaBase eds. (2021). M ...

, the hairy snails and their allies.

Subspecies

* ''Caseolus calvus calvus'' (R. T. Lowe, 1831) * ''Caseolus calvus galeatus'' (R. T. Lowe, 1862) The subspecies ''Caseolus calvus galeatus'' (R. T. Lowe, 1862) endemic to

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

is globally extinct.Fontaine B., Bouchet P., Van Achterberg K., Alonso-Zarazaga M. A., Araujo R. et al. (2007). "The European union’s 2010 target: Putting rare species in focus." ''Biological Conservation'' 139: 167-185. Table 2 on the page 173.
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Distribution

This species of land snail lives in

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

References

Endemic fauna of Madeira Molluscs of Europe calvus Gastropods described in 1831 Taxa named by Richard Thomas Lowe {{Geomitridae-stub