Pachnodus niger 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Cerastidae

Scientific Name: Pachnodus niger (Dufo, 1840)
Taxonomic Notes: Two subspecies have been described: P. n. niger (Dufo, 1840) and P. n. subfuscus Gerlach, 1994.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2009
Date Assessed: 2006-01-11
Needs updating
Assessor(s): Gerlach, J.
Reviewer(s): Miller, R.M., Pollock, C.M. & Seddon, M.B.
This species has a restricted range: it's EOO is 300 km² and its AOO is 8 km²; it is known from only 2 locations. Throughout this area, invasive species (e.g. Cinnamomum verum trees) are causing ongoing habitat deterioration. Fortunately, population are currently stable, though vulnerable to further habitat degradation.

Geographic Range [top]

Range Description:This snail is endemic to the Seychelles. Its extent of occurence (EOO) is estimated to be 300 km², and it has a total area of occupancy (AOO) of just 8 km². The two subspecies are distributed on two different islands: P. n. niger on north Mahé island (AOO = 5 km²) and P. niger subfuscus on Praslin island (AOO = 3 km²).
Countries occurrence:
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) - km2:300
Number of Locations:2Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:NoLower elevation limit (metres):150
Upper elevation limit (metres):550
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 2005, the total population was estimated at 8,000 adults: 5,000 of the subspecies P. n. niger and 3,000 of the subspecies P. n. subfuscus.
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:An arboreal species found in forest habitats, P. n. niger inhabits high forest while P. n. subfuscus is found in palm forest.
Continuing decline in area, extent and/or quality of habitat:Yes

Threats [top]

Major Threat(s): This snail species is threatened by habitat degradation, due to invasive alien species (e.g., Cinnamomum verum) which directly impact this snail's habitat. In the past, small-scale farming caused declines in habitat quality. Pachnodus niger ssp. niger has also hybridized with P. velutinus. Fortunately, however, the hybrid form has not expanded into the range of P. n. niger.

Conservation Actions [top]

Conservation Actions: P. n. subfuscus is present in the Praslin National Park.

Citation: Gerlach, J. 2009. Pachnodus niger. The IUCN Red List of Threatened Species 2009: e.T168117A6453496. . Downloaded on 19 January 2018.
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