Species

BackDiscula lyelliana (R.T. Lowe, 1852)

Discula lyelliana (R.T. Lowe, 1852)

  • 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.

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

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

Seddon (2008) suggested this species should be considered as Critically Endangered B1ab(iii) (version 3.1). The extent of occurrence is under 100 km2 and it is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of the slopes in last 150 years. There is concern for the survival of this species, as there are no known sites for the species, the island has been subject to much change in vegetation as the result of overgrazing and the species was not recorded in recent surveys by Ripken and Oliver in 1994 or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct. The species is therefore considered as Critically Endangered, Possibly Extinct.

Geographic Range:

This species is endemic to the Madeiran islands where it was reported to be restricted to Deserta Grande (Wollaston 1878). Cameron and Cook (1999) did not record this species in their survey work in 1994-8 and it was not recorded by Oliver in his surveys in 1994 (M. Seddon pers. comm. 2010).

Regions:
Portugal - Madeira
Extent of Occurrence (EOO):
100 (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:

The species was not recorded in recent surveys by Ripken and Oliver in 1994 (Oliver pers. comm. 1995) or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct.

Habitat and Ecology

The habitat is uncertain, but likely to be amongst rocks on grassy slopes or within scree.

Major Threat(s):

The species is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of slopes in the last 150 years.

Conservation Actions

Surveys are needed to determine if the species is still extant.