IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

BackPlutonia angulosa (Morelet, 1860)

Plutonia angulosa (Morelet, 1860)

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

Countries of Occurrence:
Portugal - Azores

Archipelago(s):
Azores

Assessor/s:
Frias Martins, A.

Reviewer/s:
Neubert, E. & Nichols, C.

Contributor/s:

Facilitators / Compilers/s:


Assessment Rationale:

Although lacking quantitative information, the history of the latter 30 years shows that there is a severe reduction in the availability of this species, namely its absence from the collected material of the last five years. The species is now restricted to the type locality and has an extent of occurrence of less than 100 km2 and an area of occupancy of less than 10 km2. Its type locality (Top of Pico Alto), to where it appears to be restricted, is already a natural reserve. However, urgent, stronger protective measures should be considered, namely extending the protected area to lower altitude in order to provide an appropriate forested habitat that could enable a better fixation of humidity. Due to its small range and the decline in extent and quality of habitat this species has been assessed as Critically Endangered (CR) B1ab(iii,iv)+2ab(iii,iv).

Geographic Range:

This species is found on the island of Santa Maria, Azores.

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

Population:

Plutonia angulosa appears to be restricted to the type locality, Pico Alto, Santa Maria, at around 500 m (Mordan and Martins 2001). It was, however, collected at the base of the mountain in 1974 and on the nearby Pico das Cavacas in 1994 (A. Martins pers. comm 2010) . This species is very rare and has not been collected by the latest missions to Santa Maria, during the last 5 years (A. Martins pers. comm. 2010).

Habitat and Ecology

Plutonia angulosa lives in mountain forested habitats, endemic and secondary, under dead leaves and rotting branches, and among the rhizomes of Hedychium gardneranum.

Major Threat(s):

Plutonia angulosa is probably the rarest species of the genus in the Azores. Although it was collected at the base of Pico Alto in 1974 and on Pico das Cavacas in 1994, it is now restricted to the top of Pico Alto, and has not been reported in the collecting trips of the last 5 years. The main threat could be the disappearance of its endemic habitat, as the species adaptation to secondary forest habitat has not been successful.

Conservation Actions

The Pico Alto complex should be strictly protected in its entirety, down to its very base; its forested area, including the secondary forest, should be left untouched. Currently only the top of Pico Alto is protected as a natural reserve. The climate in Santa Maria (highest point about 550 m) is becoming drier (A. Martins pers. obs. 2010) and some as yet undescribed taxa, more or less circumscribed to Pico Alto, are becoming dangerously rare or feared to have already disappeared.