Post by Melanie on Dec 17, 2014 21:45:10 GMT
Scientific Name: Discula lyelliana
Species Authority: (R.T. Lowe, 1852)
Assessment Information [top]
Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2013
Date Assessed: 2010-08-31
Assessor(s): Seddon, M.
Reviewer(s): Cameron, R., Groh, K., Cuttelod, A. & Neubert, E.
Justification:
Seddon (2008) suggested this species should be considered as Critically Endangered B1ab(iii) (version 3.1). The extent of occurrence is under 100 km2 and it is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of the slopes in last 150 years. There is concern for the survival of this species, as there are no known sites for the species, the island has been subject to much change in vegetation as the result of overgrazing and the species was not recorded in recent surveys by Ripken and Oliver in 1994 or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct. The species is therefore considered as Critically Endangered, Possibly Extinct.
History:
1996 – Critically Endangered (Baillie and Groombridge 1996)
1996 – Critically Endangered
1994 – Extinct? (Groombridge 1994)
Geographic Range [top]
Range Description: This species is endemic to the Madeiran islands where it was reported to be restricted to Deserta Grande (Wollaston 1878). Cameron and Cook (1999) did not record this species in their survey work in 1994-8 and it was not recorded by Oliver in his surveys in 1994 (M. Seddon pers. comm. 2010).
Countries:
Possibly extinct:
Portugal (Madeira)
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: The species was not recorded in recent surveys by Ripken and Oliver in 1994 (Oliver pers. comm. 1995) or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct.
Population Trend: Unknown
Habitat and Ecology [top]
Habitat and Ecology: The habitat is uncertain, but likely to be amongst rocks on grassy slopes or within scree.
Systems: Terrestrial
Use and Trade [top]
Use and Trade: The species is not known to be utilised, although occasionally sold by shell collectors.
Threats [top]
Major Threat(s): The species is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of slopes in the last 150 years.
Conservation Actions [top]
Conservation Actions: Surveys are needed to determine if the species is still extant.
www.iucnredlist.org/details/6730/0
Species Authority: (R.T. Lowe, 1852)
Assessment Information [top]
Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2013
Date Assessed: 2010-08-31
Assessor(s): Seddon, M.
Reviewer(s): Cameron, R., Groh, K., Cuttelod, A. & Neubert, E.
Justification:
Seddon (2008) suggested this species should be considered as Critically Endangered B1ab(iii) (version 3.1). The extent of occurrence is under 100 km2 and it is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of the slopes in last 150 years. There is concern for the survival of this species, as there are no known sites for the species, the island has been subject to much change in vegetation as the result of overgrazing and the species was not recorded in recent surveys by Ripken and Oliver in 1994 or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct. The species is therefore considered as Critically Endangered, Possibly Extinct.
History:
1996 – Critically Endangered (Baillie and Groombridge 1996)
1996 – Critically Endangered
1994 – Extinct? (Groombridge 1994)
Geographic Range [top]
Range Description: This species is endemic to the Madeiran islands where it was reported to be restricted to Deserta Grande (Wollaston 1878). Cameron and Cook (1999) did not record this species in their survey work in 1994-8 and it was not recorded by Oliver in his surveys in 1994 (M. Seddon pers. comm. 2010).
Countries:
Possibly extinct:
Portugal (Madeira)
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: The species was not recorded in recent surveys by Ripken and Oliver in 1994 (Oliver pers. comm. 1995) or by Cameron and Cook in various surveys (1999) in spite of the large fairly conspicuous shell. This suggests that it is either very rare or possibly extinct.
Population Trend: Unknown
Habitat and Ecology [top]
Habitat and Ecology: The habitat is uncertain, but likely to be amongst rocks on grassy slopes or within scree.
Systems: Terrestrial
Use and Trade [top]
Use and Trade: The species is not known to be utilised, although occasionally sold by shell collectors.
Threats [top]
Major Threat(s): The species is only present on one island where overgrazing by goats has lead to massive changes in vegetation and stability of slopes in the last 150 years.
Conservation Actions [top]
Conservation Actions: Surveys are needed to determine if the species is still extant.
www.iucnredlist.org/details/6730/0
