IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

Back • Caseolus commixtus (Lowe, 1854)

Caseolus commixtus (Lowe, 1854)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
LC Least Concern
IUCN Red List Status:
  • EX
  • EW
  • CR
  • EN
  • VU
  • NT
  • LC
  • DD
  • NE

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

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Assessor/s:
Seddon, M.B.

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

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

Facilitators / Compilers/s:

Assessment Rationale:

This species is endemic to Porto Santo (Madeira, Portugal), where it is widespread on the main island. It is found at 12 locations and about 30 sites, mainly on the eastern side, but also on three of the offshore islets and isolated sites at the west end of the island. Even though it has a restricted range (extent of occurrence of 100 km2), the population is thought to be stable and there are more than ten locations and the quality of the habitat is not declining enough to impact significantly the whole species. The species should be monitored for future declines, as if significant development took place it would merit a higher listing.

The species was previously listed as Vulnerable on the basis of its small restricted range. Further quantitative survey data shows the species to be present on three of the offshore islets, which are protected sites with minimal threats , and as such this species has a revised listing as Least Concern (LC).

Geographic Range:

This species is endemic to Madeiran islands where it is only found on Porto Santo, where it is widespread on the main island. It is found at 12 locations and about 30 sites, mainly on the eastern side, but also on three of the offshore islets and isolated sites at the west end of the island (Cameron and Cook 1998, Seddon 2008).

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 locally abundant and as such is thought to be stable.

Habitat and Ecology

This species occurs in grassland where it is found on the underside of stones, on scree slopes and at the base of crags.

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 EU Habitats and Species Directive Annex II and the Council of Europe Bern Convention Appendix 2.  This species is widely distributed on Porto Santo, so recommended conservation actions include management of the protected areas for maintenance of this species and monitoring of the protected areas to ensure no loss of further habitat and subpopulations.