Aaadonta fuscozonata ssp. depressahttp://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T198786A2535008.en
|Scientific Name:||Aaadonta fuscozonata ssp. depressa|
|Species Authority:||Solem, 1976|
|Red List Category & Criteria:||Critically Endangered B1ab(i,ii,iii)+2ab(i,ii,iii) ver 3.1|
|Reviewer(s):||Seddon, M., Barker, G. & Pippard, H.|
Aaadonta fuscozonata depressa is a minute ground-dwelling snail for which only one live shell was found at a single locality on Ngemelis in 2005. The subspecies was previously known only from Peleliu, where three specimens were collected at two localities in 1936 by Y. Kondo. However, no specimens were found on this island in recent surveys. The species is listed as Critically Endangered, based on the limited area of occupancy, the single location, and a decline in its native habitat. Surveys to determine the current distribution of this species and population size, status and trends are recommended.
The historical geographic range of A. fuscozonata depressa was 12km2. The subspecies was previously known only from Peleliu, where three specimens were collected at two localities in 1936 by Y. Kondo. The species was probably historically more abundant prior to this - indeed, substantial change had already occurred on that island by that time. The area of occupancy for this subspecies is now estimated at 1km2, since few specimens have been found recently at a single locality on Ngemelis, a smaller nearby island.
|Estimated area of occupancy (AOO) - km2:||1|
|Continuing decline in area of occupancy (AOO):||Yes|
|Estimated extent of occurrence (EOO) - km2:||12|
|Continuing decline in extent of occurrence (EOO):||Yes|
|Number of Locations:||1|
|Lower elevation limit (metres):||1|
|Upper elevation limit (metres):||200|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This subspecies was previously known only from Peleliu, where three specimens were collected at two localities in 1936 by Y. Kondo (Solem 1976). Only one live shell was found at a single locality in 2005 (R.J. Rundell, 2005, unpublished data) on Ngemelis. However, no specimens were found on Peleliu in recent surveys. (Rundell 2003 unpublished data, Rundell 2005 and 2010).|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This is a ground dwelling species recorded from tropical moist lowland forest.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||This species is not utilized.|
A. fuscozonata depressa is threatened by destruction and modification of native lowland forest. Therefore it is not surprising that the subspecies has probably been extirpated from the highly modified island of Peleliu, whose forest was burned in World War II with flamethrowers (Hinz 1995; Crombie and Pregill 1999). Disruption of the ground, rocks and leaf litter may be of particular significance to this and other endodontid species. Endodontoid land snails are among the most threatened land snails on Pacific Islands in the few places where they still exist (Solem 1983), and therefore the fact that this subspecies is still extant is important. This subspecies is in need of conservation attention.
Field work to define the current distribution of this species, as well as research on its population status and trends, is required. Identification of priority sites for species conservation (e.g. key biodiversity areas that include threatened land snails) and reducing the impacts of human activities, especially on the small islands, is also urgently needed. The Palau Conservation Society has been supportive of recent land snail survey work in Palau.
Colin, PL. 2009. Marine Environments of Palau. Indo-Pacific Press, San Diego.
Cowie, RH, Allison, A, Howarth, FG, Samuelson, GA, Evenhuis, NL. 1996. Impacts of the Palau Compact Road: Survey of the non-marine fauna of the Island of Babeldaob. Will Chee Planning, Honolulu.
Crombie, R.I. and Pregill, G.K. 1999. A checklist of the herpetofauna of the Palau Islands (Republic of Belau), Oceania. Herpetological Monographs 13: 29-80.
Hinz, E. 1995. Pacific Island Battlegrounds of World War II: Then and Now. The Bess Press, Honolulu.
IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.2). Available at: http://www.iucnredlist.org. (Accessed: 17 October 2012).
Motteler, LS. 2006. Pacific Island Names. Bishop Museum Press, Honolulu.
Rundell, RJ. 2005. The land snails of Belau: Survey of the 16 states.
Rundell, RJ. 2008. Cryptic diversity, molecular phylogeny and biogeography of the rock- and leaf litter-dwelling land snails of Belau (Republic of Palau, Oceania). Philosophical Transactions of the Royal Society of London B 363: 3401-3412.
Rundell, RJ. 2010. Diversity and conservation of the land snail fauna of the western Pacific islands of Belau (Republic of Palau, Oceania). American Malacological Bulletin 28: 81-90.
Smith, B.D. 1993. Working list of the terrestrial gastropods of Palau, Caroline Islands. Working List No. 4. Dickinson Memorial Mollusc Collection, Marine Laboratory, University of Guam.
Solem, A. 1976. Endodontoid land snails from Pacific islands (Mollusca: Pulmonata: Sigmurethra). Part I. Family Endodontidae. Field Museum of Natural History, Chicago.
Solem, A. 1983. Endodontoid land snails from Pacific islands (Mollusca: Pulmonata: Sigmurethra). Part II. Families Punctidae and Charopidae. Zoogeography. Field Museum of Natural History, Chicago.
|Citation:||Rundell, R.J. 2012. Aaadonta fuscozonata ssp. depressa. The IUCN Red List of Threatened Species 2012: e.T198786A2535008. http://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T198786A2535008.en . Downloaded on 10 October 2015.|
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