''Theba macandrewiana'' is a species of land snail of the family

Helicidae Helicidae is a large, diverse family (biology), family of small to large, air-breathing land snails, sometimes called the "typical snails." A number of species in this family are valued as food items, including ''Cornu aspersum'' (formerly ''Heli ...

endemic Endemism is the state of a species being found 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 found elsew ...

to the

Savage Islands The Savage Islands or Selvagens Islands ( pt, Ilhas Selvagens ; also known as the Salvage Islands) are a small Portuguese archipelago in the North Atlantic Ocean, south of Madeira, and north of the Canary Islands.

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 ...

. Its shell is around in length.

Distribution and habitat

It is present in the three islands (

Selvagem Grande Selvagem Grande Island is part of the Savage Islands archipelago, which themselves are part of the Portuguese Autonomous Region of Madeira in the North Atlantic Ocean. The island () belongs to the northeast group of the Savage Islands, which com ...

Selvagem Pequena Selvagem Pequena Island () is an island in the southeast group of the Savage Islands, Madeira, Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Ibe ...

and Fora Islet) where it occurs on rocky and sandy soils, beneath rocks or associated to grasses from in altitude. It is the only non-marine gastropod species known from the archipelago.

Threats

The species was threatened by previous introduction of rabbits (''

Oryctolagus cuniculus The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (including Spain, Portugal, and southwestern France), western France, and the northern Atlas Mountains in northwest Africa. It has b ...

''), mice (''

Mus musculus Mus or MUS may refer to: Abbreviations * MUS, the NATO country code for Mauritius * MUS, the IATA airport code for Minami Torishima Airport * MUS, abbreviation for the Centre for Modern Urban Studies on Campus The Hague, Leiden University, Neth ...

'') and the tobacco tree (''

Nicotiana glauca ''Nicotiana glauca'' is a species of flowering plant in the tobacco genus Nicotiana of the nightshade family Solanaceae. It is known by the common name tree tobacco. Its leaves are attached to the stalk by Petiole (botany), petioles (many other ' ...

'') to the Selvagem Grande which were effectively eradicated in the early 2000's. Today, the species is susceptible to soil erosion and consequent landslides from rainstorms that affect the arid archipelago and also native lizards that may predate on eggs. In the longer term the species could be threatened by increased frequency of droughts and sea level changes due to climate change. It represents about 35% of the diet of

yellow-legged gull The yellow-legged gull (''Larus michahellis'') is a large gull found in Europe, the Middle East and North Africa, which has only recently achieved wide recognition as a distinct species. It was formerly treated as a subspecies of either the Cas ...

s that breed on the islands.

References

{{Taxonbar, from=Q14752136 Helicidae Molluscs of Africa Savage Islands Taxa named by Ludwig Karl Georg Pfeiffer Gastropods described in 1853