IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackAtlantica guerinianus (Lowe, 1852)

Atlantica guerinianus (Lowe, 1852)

Madeiran Land Snail

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Discidae
CR Critically 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.

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

This species was originally listed as Possibly Extinct by Wells and Chatfield (1992) and Groombridge (1994). It was reassessed as Extinct in the 1996 list (Baillie and Groombridge 1996) as the species has not been recorded since the 1860s despite intensive searching by different field researchers between 1970's and 1990's.

Cameron and Cook (1999) rediscovered the species at the west end of the island at two close, but separate locations, in well vegetated fragments of habitats, which at this time were relatively undisturbed. Only fresh shells were recorded to date, but these were sufficiently fresh to assume the species is living at these sites. Cameron (pers. comm. 2010) recently visited these sites and found that at both sites there has been recent change, with disturbance of the habitat. At Ponta do Pargo recent fires have disturbed the habitat and at Paul do Mar there has been a hotel development with possible loss of this site. Hence the species has been reassessed as Critically Endangered (CR B1ab(iii,v)).

Geographic Range:

Atlantica guerinianus is endemic to the Madeiran Islands, where it was originally recorded from Riberia de Santa Luzia on Madeira (Wollaston 1878,  Seddon 2008). Cameron and Cook (1999) recorded it from two sites, one site close to Ponta do Pargo at the far west of the main island of Madeira and the other near Paul do Mar. Other surveys failed to find other sites for this species, despite intensive efforts between 1970s and 1990s (Seddon 2008). One site has undergone recent change due to hotel developments close by and the other site has been disturbed by recent fires (Cameron, pers. comm. 2010).

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:

After 80 years of being regarded as extinct, the species was rediscovered in a different area of the island some 25 km from the original type locality. One of these two sites was close to hotel development and may well have been lost (Cameron pers. comm. 2010).

Habitat and Ecology

In 1878, Wollaston described the habitat as intermediate to high elevations, confined to deep wooded ravines under stones and leaf litter. Between 1878 and 1999 there were no records of this species and it was believed to be extinct, as the Riberia de Sta Luzia had changed considerably since Wollaston had recorded it there.  In 1999 the species was rediscovered, at two sites, one of which was scrubby habitats and the other was Laurisilvaforest remnants (Cameron, pers. comm. 2010).

Major Threat(s):

At Ponta do Pargo recent fires have disturbed the habitat and at Paul do Mar there has been a hotel development with possible loss of this site.

Conservation Actions

The species is on the EU Habitats and Species Directive Annex II and requires an SPA, however, it was thought to be extinct until recently. There are few protected areas in the range of this species, and establishment of a small area would benefit the species through reduction of the impact of development for tourism. Habitat monitoring is required at the site to ensure disturbance is not impacting the species.