IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group


BackActinella arridens (R.T. Lowe, 1831)

Actinella arridens (R.T. Lowe, 1831)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
CR Critically Endangered
IUCN Red List Status:

Countries of Occurrence:
Portugal - Madeira


Seddon, M.B.

Cameron, R., Groh, K., Cuttelod, A. & Neubert, E.

Abreu, C.

Facilitators / Compilers/s:

Assessment Rationale:

The species was described by Wollaston (1878) as common in the intermediate elevations north of Funchal, but was rarely found by recent survey work between 1984-1999. The remaining known site is on the southern side of Madeira, where there are potential threats due to expanding urbanisation and associated infrastructure, as well as fires. The species could meet the criteria for Critically Endangered,Vulnerable and Near Threatened, based on the scale of the threats in this protected area. It was originally listed as Vulnerable in 1994, and reaffirmed as Vulnerable D2 in 2000 (M. Seddon pers. comm. 2009). Seddon (2008) proposed the species should be listed as Data Deficient (version 3.1), however in view of the threats including recent fires in the intermediate elevations north of Funchal, it is now considered Critically Endangered (CR) B2ab(iii).

Geographic Range:

This species is endemic to the Madeiran islands where it is found on Madeira mainly at intermediate elevations on rock crags (Wollaston 1878). It is rare in old records, and as such requires more survey work (Seddon 2008). At present there is only one confirmed location (Seddon 2008).

Portugal - Madeira
Extent of Occurrence (EOO):
Area of Occupancy (AOO):
Elevation Lower Limit:
Elevation Upper Limit:
Biogeographic Realms:
Endemic Madeira


There is insufficient data to establish population trends.

Habitat and Ecology

This species is found on rock crags, under and around the Sempervivum on the faces. Also found on rock ledges under leaves, around the roots of plants; under dead, loosened bark.

Major Threat(s):

This is a rare species which maybe underrecorded (Seddon 2008). The major threats lie in habitat disturbance, for example through intensive bushfires.

Conservation Actions

Conservation actions required for this species include review of the population distribution, as well as habitat monitoring, especially for highland areas vulnerable to fire. The likely area of distribution lies partly in  protected areas (Laurel forest protected area, and the Maciço Montanhoso Central protected area (Central Mountainous Massif).