IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackLampadia webbiana (Lowe, 1831)

Lampadia webbiana (Lowe, 1831)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Helicidae
EN Endangered
IUCN Red List Status:

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

Assessor/s:
Seddon, M.B.

Reviewer/s:
Neubert, E., Cameron, R., Groh, K. & Cuttelod, A.

Contributor/s:
Cameron, R.

Facilitators / Compilers/s:


Assessment Rationale:

This species has a restricted range and is known from three locations. It was originally assessed as Vulnerable D2, however potential loss of the subpopulation on Cima in combination with pressures to habitats from tourist development are additional threats to the remaining subpopulations which had been impacted by rodent predation, and as such the status has been amended to Endangered (EN) B1ab(ii,iii)+2ab(ii,iii). Further research is needed into the impact of rodent predation on the populations of these large helicids, as well as the impact of the potential competitor Theba pisana.

Geographic Range:

This species is endemic to the Madeiran archipelago where it is only known from Porto Santo and adjacent islet of Ilheu de Cima (Seddon 2008; Cameron, pers. comm., 2010).  Cameron and Cook's recent survey work in 2001 on Cima did not refind this population (Cameron, pers. comm., 2010) and so there is a possible reduction in the range that requires further research.  The remaining population on Porto Santo is restricted to three small hills at eastern end of the island.

Regions:
Portugal - Madeira
Extent of Occurrence (EOO):
42 (km2)
Area of Occupancy (AOO):
12 (km2)
Elevation Lower Limit:
(m)
Elevation Upper Limit:
(m)
Biogeographic Realms:
Palearctic
Presence:
Extant
Origin:
Endemic Madeira
Seasonality:
Resident

Population:

There is evidence that adult shells are being predated by introduced rodents, hence the populations are known to be in decline.

Habitat and Ecology

This species is found on the underside of stones on grassy areas, mainly on the eastern peaks of the island.

Major Threat(s):

Rodents catch and eat this species, making characteristic holes through the apical whorls of the shell to extract the animal (Seddon 2008). Habitat management in this area of Porto Santo has changed over the years, with increasing impact from tourist developments, such that the grassland may be degrading in quality.

Conservation Actions

Further research is required to confirm the loss of the population on Cima, as well as resurvey of populations on the main island (Groh, pers. comm., 2010).  Control of introduced rodents would be beneficial to this species as it would reduce impact on the adult breeding part of the population.