IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackCaseolus consors (Lowe, 1831)

Caseolus consors (Lowe, 1831)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
LC Least Concern
IUCN Red List Status:

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

Assessor/s:
Seddon, M.B.

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

Contributor/s:
Killeen, I. & Teixeira, D.

Facilitators / Compilers/s:


Assessment Rationale:

On Porto Santo, this species has an restricted extent of occurrence ( EOO of 100 km2), with 10 localities (and more than 20 sites), however although habitat has declined over last 30 years, it does not meet the small number of localities for a higher threat category, or the Vulnerable D2 category following the changes to the criteria since 2000. The present population abundance and habitat, suggests that it is not highly threatened as it is fairly widespread at the eastern end of the island. However these mainland populations are most susceptible, given the multiple threats causing habitat degradation and impact of non-native species. Hence, the species would move to a more threatened category should habitat degradation accelerate. The species should be monitored for future declines, as if significant development took place it would merit a higher listing. The IUCN Red List criteria have changed since 2000, hence this species is now considered as Least Concern (LC).

Geographic Range:

This species is endemic to Madeiran islands; it is only known from the small island of Porto Santo, where it is widespread at the eastern end of the island.

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 is frequent in samples from the 10 locations, so the species is viewed as stable.

Habitat and Ecology

This species is found on the underside of stones on scree slopes and at the base of crags within grassland.

Major Threat(s):

The population on the mainland are most susceptible from habitat loss from tourist development or habitat degradation due to invasive species (plants), fire or tipping or loss of populations due to introduced rodents.

Conservation Actions

This species is listed on the Council of Europe Berne Convention Appendix 2, and later on the EUHSD annexes II/IV.  It was originally listed by IUCN 1990 as Rare, the species was not assessed for the 1996 list and placed as Near Threatened in 2000. The placement on the EUHSD annexes means an SAC should have been created for this species. Part of Porto Santo is now a protected area.