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Silhouettia silhouettae 

Scope: Global
Language: English
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_onStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Streptaxidae

Scientific Name: Silhouettia silhouettae (Martens, 1898)

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 is assessed as Vulnerable because it has a restricted distribution and the habitat within this area is deteriorating. Both the EOO and AOO are estimated at 18 km² and it is found in only 10 locations. Invasive non-native plant species (e.g. Cinnamomum verum) are causing habitat degradation throughout this species' range. Fortunately, it remains abundant to date.

Geographic Range [top]

Range Description:Endemic to Seychelles islands, this snail species is found only on Silhouette island. Both its extent of occurrence (EOO) and area of occupancy (AOO) are estimated to be 18 km².
Countries occurrence:
Native:
Seychelles (Seychelles (main island group))
Additional data:
Estimated area of occupancy (AOO) - km2:18Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:18
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):300
Upper elevation limit (metres):770
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population was estimated at 1.7 million individuals in 2005.
Current Population Trend:Stable
Additional data:
Number of mature individuals:1700000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is restricted to high montane forest, from 300-770 m.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): Habitat degradation caused by invasive exotic species (e.g., Cinnamomum verum) is currently the main threat this snail faces. Small-scale wood plantations were a threat in the past.

Conservation Actions [top]

Conservation Actions: No conservation measures have been take, though a systematic monitoring scheme is in place. Silhouette island should receive legal protection in order to protect threatened habitats, and invasive species must be controlled. Research into this species' life history and ecology would be beneficial.

Citation: Gerlach, J. 2009. Silhouettia silhouettae. The IUCN Red List of Threatened Species 2009: e.T168153A6460773. . Downloaded on 24 September 2017.
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