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Priodiscus costatus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Streptaxidae

Scientific Name: Priodiscus costatus Gerlach, 1995

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(iii)+2ab(iii); D2 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.
Justification:
This species has a restricted distribution, with an EOO of 600 km² and an AOO of just 8 km²; it is found in 10 locations. Within that area there is ongoing habitat degradation, as a result of invasive exotic species (e.g., Cinnamomum verum). The severity of this deterioration is unknown.

Geographic Range [top]

Range Description:Endemic to the Seychelles islands, this snail is found on the islands of Mahé, Curieuse, La Digue, and Felicite. Its extent of occurrence (EOO) is 600 km² and its area of occupancy (AOO) is 8 km².  It is possibly extinct on Praslin; there are no records of this species on the island since the 1800s.
Countries occurrence:
Native:
Seychelles (Seychelles (main island group))
Additional data:
Estimated area of occupancy (AOO) - km2:8Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:600
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:10Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):50
Upper elevation limit (metres):900
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population is estimated to have 8,000 individuals.
Current Population Trend:Stable
Additional data:
Number of mature individuals:8000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:A forest species, this snail is mainly found in lowland or palm forest.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): Vulnerable to habitat deterioration, this species is currently threatened by invasive exotic species (e.g., Cinnamomum verum) that degrade its habitat. Fires and small-scale wood plantations have caused habitat loss/degradation in the past.

Conservation Actions [top]

Conservation Actions: No conservation actions have been taken. The signficant popualtion at La Reserve-Brullee, on Mahé island, should be protected. Invasive species should be controlled throughout the Seychelles islands. Research is needed into the species' life history and ecology.

Citation: Gerlach, J. 2009. Priodiscus costatus. The IUCN Red List of Threatened Species 2009: e.T168151A6460575. . Downloaded on 24 September 2017.
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