IUCN SSC Mid-Atlantic Island Invertebrates Specialist Group

Species

Back • Leptaxis nivosa (G.B. Sowerby I, 1824)

Leptaxis nivosa (G.B. Sowerby I, 1824)

  • Kingdom: Animalia
  • Phylum:
  • Class: Mollusca
  • Order: Gastropoda
  • Family: Hygromiidae
LC Least Concern
IUCN Red List Status:
  • EX
  • EW
  • CR
  • EN
  • VU
  • NT
  • LC
  • DD
  • NE

Countries of Occurrence:
Portugal - Madeira

Archipelago(s):
Madeira

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Assessor/s:
Seddon, M.B.

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

Contributor/s:

Facilitators / Compilers/s:

Assessment Rationale:

This species is endemic to Porto Santo (Madeiran Islands), where it is abundant and widespread over the island, and although there is some evidence of rodent predation, the species is still abundant, and hence is assessed as Least Concern (LC).The two range restricted subspecies merit review, as these maybe distinct species, and as such, these may be threatened by rodent predation, although both lie in protected areas, so habitat disturbance is limited. Seddon (2008) suggested these should be assessed as Vulnerable D2 (Leptaxis nivosa calensis Baixo VU D2; Leptaxis nivosa craticulata Fora, VU D2).

Geographic Range:

This species is endemic to Porto Santo (Madeiran Islands), where it is abundant and widespread over the island. 
Mandahl-Barth (1950) recognised three subspecies from different islands. As these forms are distinct as well as geographically isolated all three are discussed here:
Leptaxis nivosa nivosa (Sowerby, 1824) occurs on the main island, and abundant and widespread,
Leptaxis nivosa calensis (Bank et al., 2002) is only found on the Ilhéu de Baixo, Porto Santo,
Leptaxis nivosa craticulata (Lowe, 1852)  is restricted to the Ilhéu de Fora, Porto Santo.

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:

Widespread and abundant on the main island, this species can be the dominant species in a sample.

Habitat and Ecology

This species is found on the underside of stones and amongst grasses on grassy unshaded areas. 

Major Threat(s):

Leptaxis nivosa is common in suitable habitats on the main island, and, as such, although there are localised threats to the species, from habitat loss related to increased tourism development, recreational use of the island and road construction, it is not believed to be threatened over its whole range. Rodent predation is known on this species, but given the abundance on the mainland, at present this has not impacted the species.

Conservation Actions

There are no known conservation actions in place for this species, although part of the range falls into Sites of Community Importance (Ilhéus do Porto Santo, Pico Branco). Further research is required to review the taxonomic status of the two island subspecies, as these are all distinct in shell morphology, and as such merit review to establish whether these maybe distinct species.