Actinella obserata


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Actinella obserata
Species Authority: (R.T. Lowe, 1852)
Taxonomic Notes:

Seddon (2008) noted that it appeared closely allied to the Quaternary fossil species Actinella (Faustella) promontoriensis, which also has a bisinuosity, which is more strongly developed, and a shell which appears more globose, with a more shouldered whorl (not as acutely keeled).  A. promontoriensis is a common fossil species on the peninsular at the eastern end of the island.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B2ab(iii) ver 3.1
Year Published: 2013
Date Assessed: 2010-09-30
Assessor(s): Seddon, M.B.
Reviewer(s): Cameron, R., Groh, K., Cuttelod, A. & Neubert, E.
Contributor(s): Teixeira, D.

The species was listed as Vulnerable in 1994, based on Wells and Chatfield (1992). It was given a revised listing as Near Threatened in 1996, based on the same data-set. Since the Walden's surveys in 1970's there has been little new data on this species in spite of extensive survey work in the last known region on the island.  Seddon (2008) suggested the species should now be considered as Data Deficient (version 3.1) due to the lack of recent records. However based on the presence at a single location on the south coast of Madeira in a region where there has been substantial changes to habitats in the last 40 years, then using the precautionary principle, the species is now listed as Critically Endangered (CR) B2ab(iii) rather than Data Deficient. 

Geographic Range [top]

Range Description:

This species is endemic to Madeira. It is recorded from a single site on the south side of the island, close to Funchal (Seddon 2008).  There are been very few records of the Actinella fausta group of species (A. robusta, A. obserata, A. carinofausta, A. fausta) on the southern coast of Madeira, since Walden (1983) published his checklist where he suggested that there were several taxa with 'A. fausta'.

Portugal (Madeira)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There are no data on population trends, although the species is believed to be rare.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: It is believed to be present on ground and under stones in shrubby/grassland areas, but further research required to confirm the habitats.
Systems: Terrestrial

Use and Trade [top]

Use and Trade: This species is not used.

Threats [top]

Major Threat(s): The major threat in this part of Madeira is encroaching urbanisation, as well as the construction of an infrastructure to service these towns and villages.  The region had been extensively modified with agriculture, hotel construction and urbanisation since Wollaston visited the island in the 1870's.

Conservation Actions [top]

Conservation Actions: There are been very few records of the Actinella fausta group of species (A. robusta, A. obserata, A. carinofausta, A. fausta) on the southern coast of Madeira, since Walden (1983) published his checklist where he suggested that there were several taxa with 'A. fausta'.  Research is needed to establish the taxonomy and distribution of this species on the island and to make a revised conservation assessment with suggested conservation actions.

Bibliography [top]

IUCN. 2011. IUCN Red List of Threatened Species (ver. 2011.1). Available at: (Accessed: 16 June 2011).

Seddon, M.B. 2008. An illustrated compendium ofthe landsnails and slugs of the Madeiran archipelago. Studies in Biodiversity and Systematics of Terrestrial Organisms from the National Museum of Wales. Biotir Reports.

Walden, H.W. 1983. Systematic and biogeographical studies of the terrestrial Gastropoda of Madeira. With an annotated Check-list. Annales Zoologica Fennica 20: 255-275.

Citation: Seddon, M.B. 2013. Actinella obserata. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 30 August 2015.
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