Countries of Occurrence:
Portugal - Madeira
Cameron, R., Groh, K., Teixeira, D., Cuttelod, A. & Neubert, E.
Abreu, C. & Teixeira, D.
Facilitators / Compilers/s:
Seddon (2008) suggested the species may qualify as Endangered B1 a, b(iii) as it is only found in a small area, with four known localities, and in coastal habitats and intermediate valleys with changing vegetation impacting habitat quality.
Spirorbula squalida is restricted to the coastal regions in the south near Funchal and western Madeira near Porto Moniz. Despite intensive surveys (1984-2003) the species has not yet been recorded in other parts of the south coast. It was been re-assessed as Vulnerable in 2000 from Near Threatened (1996) and Rare (1994). It remains rare, although it is cryptic and hence difficult to find in surveys. Fire events have been reported in the region inland of Funchal, which would impact as one of the four sites and hence the species listing is retained as Vulnerable (VU) D2. As the sites south of Porto Moniz should lie in the protected area of Achadas da Cruz, it is not listed as Endangered.
This species is endemic to Madeira, where it is found mainly at the west end of the main island, although there are isolated records from valleys to north-west of Funchal (Seddon 2008). This has changed little from Wollaston's time (1878), when the species was described as rare, mainly from Riberia de Janella to Porto Moniz and near Funchal (still present) and along north coast (no recent records). There are Pleistocene fossils from Canical.
The species is never abundant when found (Seddon, pers. comm., 2010).
This species is found on walls, rocky faces and slopes with large boulders, usually very cryptic, as it coats its shell with mud (Seddon 2008).
There is a possible decline in the quality of habitat in the coastal area around Porto Moniz, where non-native plants have become established. This species is very rare but difficult to survey due to the cryptic nature of the species in its habitat. Non-native plant species maybe impacting habitats in the valleys, as could other types of habitat disturbance on the rock faces and walls. Fire events have been reported in the region.
This species is very rare but difficult to survey due to the cryptic nature of the species in it's habitat. Habitat monitoring maybe the best indication for the status of the species, given the cryptic habits.