Glabrennea silhouettensis 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Streptaxidae

Scientific Name: Glabrennea silhouettensis
Species Authority: (Verdcourt, 1994)
Gulella silhouettensis Verdcourt, 1994
Taxonomic Notes: This species recently changed genus, from Gulella to Glabrennea (Schileyko 2000).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii,v)c(iv)+2ab(iii,v)c(iv) ver 3.1
Year Published: 2009
Date Assessed: 2006-01-11
Assessor(s): Gerlach, J.
Reviewer(s): Miller, R.M., Pollock, C.M. & Seddon, M.
This species is Critically Endangered due to its extremely restricted range (its EOO and AOO are only 0.07 km², and it is known from only 1 location), combined with a high sensitivity to habitat change. Such changes are already taking place: rainfall is decreasing and dry periods are becoming increasingly intense, causing prolonged dessication of previously water-saturated habitats, such as the moss forest this species inhabits. This habitat decline may cause a decline in the population.

Geographic Range [top]

Range Description: Endemic to the Seychelles islands, this snail species is found on the summit of Mt. Dauban, on Silhouette island. Its extent of occurrence (EOO) and area of occupancy (AOO) are both estimated to be 0.07 km².
Countries occurrence:
Seychelles (Seychelles (main island group))
Estimated area of occupancy (AOO) - km2: 0.07
Continuing decline in area of occupancy (AOO): No
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 0.07
Continuing decline in extent of occurrence (EOO): No
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
Continuing decline in number of locations: No
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 750
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 be less than 7,560 individual in 2005.
Current Population Trend: Unknown
Additional data:
Number of mature individuals: 1000-7560 Continuing decline of mature individuals: Unknown
Extreme fluctuations: Unknown Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: The species is restricted to the water-saturated leaf litter in montane moss forest, from 750-770 m.
Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes

Threats [top]

Major Threat(s): This snail is highly vulnerable to habitat change, especially changes in rainfall patterns due to climate change. Such changes are apparent, with increasing intensity of dry periods causing prolonged dessication of previously water-saturated habitat. In addition, invasion by introduced Cinnamomum verum plants may be a stress.

Conservation Actions [top]

Conservation Actions: No conservation actions have been taken, though a systematic monitoring scheme is in place. Silhouette island needs legal protection in order to protect the range of this species.

Citation: Gerlach, J. 2009. Glabrennea silhouettensis. The IUCN Red List of Threatened Species 2009: e.T168146A6459829. . Downloaded on 25 November 2015.
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