IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group


BackGeomitra watsoni (J.Y. Johnson, 1897)

Geomitra watsoni (J.Y. Johnson, 1897)

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

Countries of Occurrence:
Portugal - Madeira


Neubert, E. & Allen, D.J.


Facilitators / Compilers/s:

Assessment Rationale:

This species is endemic to the Madeiran Archipelago, where it has recently been refound at two locations on the Ilhéu dos Desembarcadouros and the Ilhéu de Farol, off the Pta da Sao Lourenco, eastern Madeira (D. Teixeira pers. comm. 2016). The extent of occurrence (EOO) and the area of occupancy (AOO) are both estimated to be less than 8 km2 . In 2011 this species was assessed as Data Deficient, as there was insufficient recent data confirming the presence on the islets. There is now a monitoring programme ongoing for this species, with the aim of maintaining the populations, which at present seem stable. Future threats come from predation by mice and changing vegetation due to large Gull colonies with their bird droppings and increased frequency of drought events. The species thus meets the criteria for Endangered (EN B1ab(iii,v)+2ab(iii)).

Geographic Range:

This species is endemic to the Madeiran Archipelago, where it has recently been refound on the Ilhéu dos Desembarcadouros off the Pta. da Sao Lourenco, eastern Madeira, and on Ilhéu de Farol (D. Teixeira pers. comm. 2016). K. Groh (pers. comm. 2010) recorded two fresh shells from the peninsula but their origin is uncertain. In the Quaternary fossil deposits at Caniçal (Pta. da Sao Lourenco) shells of this species are abundant (Seddon 2008).

Portugal - Madeira
Extent of Occurrence (EOO):
8 (km2)
Area of Occupancy (AOO):
8 (km2)
Elevation Lower Limit:
10 (m)
Elevation Upper Limit:
80 (m)
Biogeographic Realms:
Endemic Madeira


A species that is present in low densities (D. Teixeira pers. comm. 2008). The species is still present on offshore islets, where it was recorded in 2000 in both islets, and since then the populations are stable during frequent visits to monitor this species.

Habitat and Ecology

The species is found on rocks within grassland and rocky slopes.

Major Threat(s):

The main threats are from the presence of Gull colonies with their bird droppings causing acidification and disturbance from trampling. There is an additional threat from predation by mice. The islets are also subject to changing vegetation due to increased frequency of drought events.

Conservation Actions

There is a Life Project survey work ongoing to monitor the status of this species and a species conservation action plan is planned for 2019. The two islets are candidate AZE sites for this and other species. Ilhéu do Desembarcadouro is a Natura 2000 site (Reserva Natural Integral do Ilhéu do Desembarcadouro), and both islets are within the Parque Natural da Madeira.