IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackCaseolus calvus (Lowe, 1831)

Caseolus calvus (Lowe, 1831)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
EN 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:

This species is very rare and localised, although survey work in the 1990’s found new sites. Although much of its distribution falls within protected areas the impact of the fires in August 2010 may well have impacted this species, and as such surveys are urgently needed to review the status of this species. It is now considered as Endangered (EN) B1ab(iii)+2ab(iii).

The species was originally assessed under the name Lemniscia calva and was last assessed as Vulnerable, based on surveys in the late 1990's indicating a narrow range and potential threats. The species has been revised as a result of recent changes to the habitats.

Geographic Range:

This species is endemic to the Madeiran islands. It is only found in the central part of Madeira, usually at intermediate to high elevations (from 600 m asl).  It is found on the summit ridges around Pico Areiro and Pico Ruivo where it is uncommon (Seddon 2008).

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

Population:

There is no recent data on population trends.

Habitat and Ecology

The species is found under stones on steep grassy slopes, amongst Sempervivum on crags at high elevations and in the litter of ledges and at the base of perpendicular crags.

Major Threat(s):

As the habitats fall within protected areas, the threats in recent years have reduced, however the recent fires and storms  have lead to potential destabilisation of habitats.

Conservation Actions

Much of its distribution falls within protected areas however, the fires in August 2010 may well have impacted this species, and as such surveys are urgently needed to review the status of this species. Seddon (2008) suggested the status should be Endangered B2ab(iii) (version 3.1).