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Priodiscus spinosus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Streptaxidae

Scientific Name: Priodiscus spinosus Gerlach, 1995

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2009
Date Assessed: 2006-01-11
Annotations:
Needs updating
Assessor(s): Gerlach, J.
Reviewer(s): Miller, R.M., Pollock, C.M. & Seddon, M.B.
Justification:
The species is assessed as Critically Endangered due to its extremely limited distribution and the habitat degradation that is currently taking place across its range. It is found in just 1 location, and its EOO and AOO are both estimated to be just 2 km². Invasive non-native plant species (e.g., Cinnamomum verum) are the cause of habitat deterioration, within this species' range and throughout most of the Seychelles islands.

Geographic Range [top]

Range Description:Endemic to the Seychelles islands and found only on Silhouette island, this snail is found in just one location measuring 2 km² (extent of occurrence (EOO) and area of occupancy (AOO) both estimated to be 2 km²).
Countries occurrence:
Native:
Seychelles (Seychelles (main island group))
Additional data:
Estimated area of occupancy (AOO) - km2:2Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:2
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):500
Upper elevation limit (metres):770
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population was estimated to consist of 64,700 individuals in 2005.
Current Population Trend:Stable
Additional data:
Number of mature individuals:64700Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Restricted to high montane forests from 500-770 m.a.s.l., this snail is a predator specializing on small, soft-bodied invertebrates.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): This species is vulnerable to habitat deterioration, caused by invasive exotic plant species (e.g., Cinnamomum verum) that directly impact the natural habitat.

Conservation Actions [top]

Conservation Actions: No conservation action has been taken. Its range on Silhouette island should be protected, and invasive species must be controlled throughout the Seychelles islands. Research is needed into its life history and ecology.

Citation: Gerlach, J. 2009. Priodiscus spinosus. The IUCN Red List of Threatened Species 2009: e.T168149A6460213. . Downloaded on 24 September 2017.
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