Species

BackCaseolus abjectus (Lowe, 1831)

Caseolus abjectus (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., Cuttelod, A. & Neubert, E.

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

This species is considered as Least Concern (LC), as it is widespread and common where it occurs.

Seddon (2008) suggests the subspecies C. abjectus abjectus is Least Concern (LC), as although the species meets the range restriction criteria for Vulnerable B, the widely scattered sites (23) and availability of habitat suggests this species is not at present at risk. Nevertheless, land management is required to ensure the species continues to prosper. 

The subspecies on the Desertas, C. abjectus nesiotes is suggested as Endangered (EN) B1ab(iii), as it is restricted to Bugio and one site on Deserta Grande where the habitats have been much impacted by the goats. However the pest species has been actively reduced as part of conservation management plans reduced the degree of habitat change and soil erosion which should benefit C. abjectus nesiotes in the longer term (Seddon 2008). 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.

The species assessment has changed from Near Threatened to Least Concern, as there is new information on the extent of the range and the relative abundance of the species with detailed quantitative surveys reported in 1999.

Geographic Range:

This species is endemic to Madeiran Islands, where there are two subspecies, one from Porto Santo and the other from Bugio (Desertas) (Cameron and Cook 1999, Seddon 2008). On Porto Santo this species has a restricted distribution and it is present in four areas, mainly at the western end of Porto Santo, but extending to two hills of eastern Porto Santo (Seddon 2008). On Porto Santo, these sites are widely scattered sites and the species is abundant where found. C. abjectus nesiotes is restricted to Bugio and one site on Deserta Grande (Cameron and Cook 1999).

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 data on the population trends from the Desertas subspecies, but the Porto Santo subspecies was once very abundant (Seddon 2008).

Habitat and Ecology

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

Major Threat(s):

Disturbance of the habitat and changes in land-use management, for example, over-grazing by livestock, trampling, and loss of land through touristic and urban developments are threatening this species. The spread of Theba pisana and rodents is also a problem.

Conservation Actions

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.