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Trochulus biconicus 

Scope: Global & Europe
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Hygromiidae

Scientific Name: Trochulus biconicus (Eder, 1917)
Synonym(s):
Trichia biconica Eder, 1917
Trochulus biconica (Eder, 1917)
Taxonomic Notes: A taxonomic review of the genus Trochulus spp. is underway by Gerhard Falkner and Ted von Proschwitz.

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(ii,iii,iv) ver 3.1
Year Published: 2011
Date Assessed: 2010-10-01
Assessor(s): Rüetschi, J.
Reviewer(s): Neubert, E., Bilz, M. & Ward, J.
Justification:
The species meets the area requirements under criterion B for Endangered due to it having an extent of occurrence of less than 5,000 km2. There is evidence of ongoing habitat loss and degradation as well as population loss through the impacts of climatic change, with some populations below 2,000 m altitude being lost. Therefore, it is assessed as Endangered (EN) B1ab(ii,iii,iv).
Previously published Red List assessments:

Geographic Range [top]

Range Description:The species has a very restricted distribution with an extent of occurrence of less than 5,000 km2, and is only found in the Central Alps in Switzerland. It is known only from Kantone Nidwalden, Obwalden and Uri. There are 130 very small localities known, all between 2,100 and 2,575 m asl.
Countries occurrence:
Native:
Switzerland
Additional data:
Number of Locations:1
Lower elevation limit (metres):2100
Upper elevation limit (metres):2575
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

The density is low and the population trend is decreasing. Some populations of altitudes between 1,800 m to 2,000 m asl. no longer exist.

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species lives on alpine meadows underneath carbonate rocks which become free from snow relatively early.
Systems:Terrestrial

Threats [top]

Major Threat(s):

The populations are threatened by the climate change (Baggot 2010, unpublished). Some populations between 1800 and 2000 m no longer exist and there is a trend of the species' range reducing below 2,000 m. As a result of climate change the habitats of the populations are becoming more unstable as the cycles of freezing and thawing increase and stones are loosened with a greater risk from avalanches.

The Swiss military used the locus typicus for shooting target practice which may have had a negative impact on the species, but this stopped some years ago.

Conservation Actions [top]

Conservation Actions: The species is listed on the Swiss Red List as Vulnerable (VU) (Turner et al. 1998). The known sub-populations require monitoring to see if the apparent trend in the decline of sites of lower altitudes continues.

Citation: Rüetschi, J. 2011. Trochulus biconicus. The IUCN Red List of Threatened Species 2011: e.T22107A9360310. . Downloaded on 23 September 2018.
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