IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackGeomitra grabhami (Wollaston, 1878)

Geomitra grabhami (Wollaston, 1878)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
CR Critically Endangered
IUCN Red List Status:

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

Assessor/s:
Seddon, M.B.

Reviewer/s:
Cameron, R., Groh, K., Cuttelod, A. & Neubert, E.

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

Geomitra grabhami has not been recorded since the 1980s and its status is uncertain. At the time of description, the species was common on the north end of Deserta Grande according to Wollaston (1878). It is possible that the impact of grazing has modified the habitats in this area. Cameron and Cook (1999) surveyed ten sites on Deserta Grande, as well as making earlier collections in 1970 and 1981 and failed to find the species. Regnier et al. (2009) listed this species as Extinct, however, although there have been recent surveys that failed to find the species, given the amount of inaccessible slopes and the fact that the goats have been removed from Deserta Grande, which will allow the stabilisation of the vegetation and gradual return to past vegetation on the slopes, the species is still considered as Critically Endangered, Possibly Extinct, until further data shows the recovery of the vegetation has not lead to recovery of the species. Further work on rehabilitation of the plant communities on the islands are ongoing, and this may benefit the land-snail populations (D. Teixeira pers. comm. 2010).

Geographic Range:

This species is endemic to the Madeiran islands. It is known from the northern end of Deserta Grande, where it was recorded by Groh and Hemmen (1986), but not refound by Cameron and Cook (1999). The species has had a similar distribution for over 100 years (Wollaston 1878).

Regions:
Portugal - Madeira
Extent of Occurrence (EOO):
(km2)
Area of Occupancy (AOO):
(km2)
Elevation Lower Limit:
(m)
Elevation Upper Limit:
(m)
Biogeographic Realms:
Palearctic
Presence:
Extant
Origin:
Endemic Madeira
Seasonality:
Resident

Population:

There are no records for over 40 years.

Habitat and Ecology

This species was originally described as living amongst lichen growing on rocks (Seddon 2008).

Major Threat(s):

Currently overgrazing by introduced goats has been reduced, but it originally caused ground instability and erosion which covers the entire island. The vegetation is gradually recovering.

Conservation Actions

The goats have been removed from Deserta Grande, which will allow the stabilisation of the vegetation and gradual return to past vegetation on the slopes. Hence the species is still considered as possibly extinct, until further data shows the recovery of the vegetation has not lead to recovery of the species. Further work on rehabilitation of the plant communities on the islands are ongoing, and this may benefit the land-snail populations.