Assessment Rationale:

The present species is restricted to the southern end of Bugio, one of the islands in the Madeiran archipelago. The species was found by Cameron and Cook (1999) at each survey site at the south end of Bugio. These records are confirmed by more recent surveys in 2008 and 2013, which also show that the population trend is stable at present. A remaining threat is the increased frequency of droughts, leading to possible disturbance of habitats as well as a population decline. The species is assessed as Vulnerable under criteria B2 a,b(iii), D2; based on its limited area of occupancy (AOO), number of locations and increased frequency of droughts, which may significantly affect the population of the species in the next few years.

Geographic Range:

This species is endemic to the Madeiran Islands, where it is restricted to Bugio in the Desertas Islands. In surveys in the 1990s, Cameron and Cook (1999) found it at each survey site. Teixeira (pers. comm. 2016) has found it in repeated surveys in 2001 and 2008 at five different sites at the southern tip of Bugio.

Population:

The survey data show that this species is never found in abundance. The population is stable, according to the last surveys made by Teixeira (2008, 2013). There has been a vegetation recovery on the last six years as a consequence of habitat restoration measures implemented during the LIFE "SOS Freira do Bugio" Project (2006 to 2009). The main predator for many species of land snails was also eradicated from Bugio (the house mouse, Mus musculus), as well as rabbits, which were causing a decline in the habitat quality.

Habitat and Ecology

The species is found on grassland on slopes, where it is rare amongst plants and stones (Wollaston 1878).

Major Threat(s):

The original threats which occurred over decades were disturbances of the habitats due to overgrazing, leading to soil erosion. Since the eradication of rabbits the habitat is improving. The mice (Mus musculus), a predator of the species, have been eradicated since 2009. A remaining threat is the increased frequency of droughts, leading to possible disturbance of habitats as well as population decline.

Conservation Actions

The eradication of goats and rabbits has already been undertaken, so it is a matter of continuing management to ensure that these species do not recolonize the habitats, and that soil erosion does not take place for other reasons (e.g. fire).