''Atlantica calathoides'' is a species of land snail belonging to the family

Gastrodontidae Gastrodontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Gastrodontoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).MolluscaBase eds. (2020). MolluscaBas ...

Distribution

This species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Madeira Madeira ( ; ), officially the Autonomous Region of Madeira (), is an autonomous Regions of Portugal, autonomous region of Portugal. It is an archipelago situated in the North Atlantic Ocean, in the region of Macaronesia, just under north of ...

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

Description

(Original description) This species is very closely allied to the Madeiran '' Atlantica gueriniana'' (R. T. Lowe, 1852), but is assuredly a genuine species, and not a merely large fossil form of that shell. It is distinguished by its larger size, less discoidal shape, greater convexity beneath, more elevated spire, obsolete keel, deeply impressed suture, and much coarser, more abrupt, and prominent ribs above, resembling, in the latter respect and in the abrupt ending of the ribs at the obsolete keel or angle of the last

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 ...

, '' Janulus calathus'' (R. T. Lowe, 1852) (taxon inquirendum) or ''

Janulus bifrons ''Janulus'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Gastrodontidae. Species Species within the genus ''Janulus'' include:MolluscaBase eds. (2022). MolluscaBase. Janulus R. T. Lowe, 1852. ...

'' (R. T. Lowe, 1852).

Historical account

The species was first described by

Richard Thomas Lowe Richard Thomas Lowe (1802–1874) was an English botanist, ichthyologist, malacologist, and clergyman. In 1825 he graduated from Christ's College, Cambridge, and in the same year he took holy orders. In 1832 he became a clergyman in the Madeira ...

in 1863 as ''Helix calathoides''. In 2008, reserve warden Isamberto Silva and biologist Dinarte Teixeira rediscovered living populations of ''Atlantica calathoides'' on the island Deserta Grande. Specimens have since been found on two sites on Deserta Grande Island and

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

fossils have been found on the island Bugio.

Ecology

Habitat

''Atlantica calathoides'' are found in deep ravines on

Deserta Grande Island The Deserta Grande Island is the main island of the Desertas Islands archipelago, a small chain of three islands in the Portuguese Madeira Islands Archipelago of Macaronesia. It is located southeast of Madeira Island, off the western coast ...

. They can typically be seen at the base of common bracken or found underneath rocks.

Threats

The main cause of population decline is predation by

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

and

ground beetle Ground beetles are a large, cosmopolitan distribution, cosmopolitan family (biology), family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it ...

s. Habitat degradation from goat grazing,

droughts A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

and

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

s has also threatened the species.

Conservation

''Atlantica calathoides'' were one of the target species of the LIFE Recover Natura Project which ran from October 2013 to March 2019. It carried out a population study, monitoring scheme and species ecology study. During the project, new populations of ''Atlantica calathoides'' were identified and the species' conservation status was evaluated. Artificial shelters to assist in conservation were considered but it was concluded that this would not assist in conservation due to ''Atlantica calathoides'' spending extended periods of time underground. In recent decades, there has been a continued control programme for goat populations which should assist with habitat restoration. Authorities in the area introduced the programme in the 1990s and have also eradicated other introduced species such as rabbits.

References

External links

* {{Taxonbar, from=Q81850048 Gastrodontidae Taxa named by Richard Thomas Lowe Endemic fauna of Madeira Molluscs of Madeira Gastropods described in 1863