Discus guerinianus

– Endangered

Taxonomy

Kingdom:	ANIMALIA
Phylum:	MOLLUSCA
Class:	GASTROPODA
Order:	STYLOMMATOPHORA
Family:	DISCIDAE
Scientific Name:	Discus guerinianus
Species Authority:	Lowe, 1852
Common Name/s:	MADEIRAN LAND SNAIL (Eng)

Assessment Information

Red List Category & Criteria:

EN B1+B2c ver 2.3 (1994)

Year Assessed:

2000

Assessor/s:

Seddon, M.B.

Evaluator/s:

Seddon, M.B. (Mollusc Red List Authority)

Justification:

This species was originally listed as possibly extinct by Wells and Chatfield (1992) and Groombridge (1994). It was reassessed as Extinct in the 1996 list (Baillie and Groombridge 1996) as the species has not been recorded since the 1860s despite intensive searching since 1983. Cameron and Cook (1999) rediscovered the species at the west end of the island at two close, but separate locations, in drier but well vegetated regions, which were relatively undisturbed, but differed from the habitats described in Wollaston (1878). Only fresh shells have been recorded to date, but these are sufficiently fresh to assume the species is living at these sites.

History:

1983	-	Vulnerable (Wells et al. 1983)
1986	-	Vulnerable (IUCN Conservation Monitoring Centre 1986)
1988	-	Vulnerable (IUCN Conservation Monitoring Centre 1988)
1990	-	Vulnerable (IUCN 1990)
1994	-	Extinct? (Groombridge 1994)
1996	-	Extinct (Baillie and Groombridge 1996)
1999	-	Critically Endangered (Hilton-Taylor 2000)

Geographic Range

Range Description:	Discus guerinianus is endemic to the Madeiran Islands.
Countries:	Native: Portugal (Madeira)

Population

Population:	After 80 years of being regarded as extinct, the species was rediscovered in a different area of the island.
Population Trend:

Habitat and Ecology

Habitat and Ecology:	In 1878, Wollaston described the habitat as intermediate to high elevations, confined to deep wooded ravines under stones and leaf litter. No other published data is known. Since the species has only recently been rediscovered, there is no available specific information on habitat preferences.
System:	Terrestrial; Freshwater; Marine

Threats

List of Threats:

12	Unknown (ongoing)

Bibliography

Bibliography:

Baillie, J. and Groombridge, B. (compilers and editors) 1996. 1996 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.

Cameron, R.D.C. and Cook, L.M. 1999. Island land snail relocated. Journal of Molluscan Studies 65: 273-274.

Groombridge, B. (ed.) 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland.

Hilton-Taylor, C. (compiler). 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN. 1990. 1990 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

Wells, S.M. and Chatfield, J.E. 1992. Threatened non-marine molluscs of Europe. Nature and Environment (Council of Europe) No 64.

Wells, S.M., Pyle, R.M. and Collins, N.M. (compilers) 1983. The IUCN Invertebrate Red Data Book. IUCN, Gland, Switzerland and Cambridge, UK.

Wollaston, T.V. 1878 Testacea Atlantica or the land and freshwater shells of Azores, aderiras, Salvages, Canaries, Cape Verdes and Saint Helena. London; Reeve.

Citation:	Seddon, M.B. 2000. Discus guerinianus. In: IUCN 2007. 2007 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 12 May 2008.
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