Aaadonta constricta ssp. constricta 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Endodontidae

Scientific Name: Aaadonta constricta ssp. constricta
Species Authority: (Semper, 1874)
Parent Species:

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii)+2ab(i,ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2011-08-22
Assessor(s): Rundell, R.J.
Reviewer(s): Pippard, H., Seddon, M. & Barker, G.

The sub-species is listed as Critically Endangered. It is a single island endemic, and the very small area where it is currently found, relative to where it was found in 1936, is of particular concern, especially given the fragility of endodontid populations elsewhere in the Pacific. It is now known from a single location and its forest habitat is experiencing declines in quality and extent. Site protection is required, and surveys to determine the current distribution of this species and its population size, status and trends are also recommended.

Geographic Range [top]

Range Description:

The historical geographic range of A. constricta constricta was 12km2. The area of occupancy for this subspecies is now estimated at 1.5km2, reflecting the single locality in native forest where very few specimens were found in recent surveys.

Countries occurrence:
Estimated area of occupancy (AOO) - km2:0.5
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 [top]

Population: This subspecies was previously known from several localities on Peleliu, where a total of 82 specimens were collected by Y. Kondo in 1936 (Solem 1976). In 2005 surveys, seven live shells and three dead shells were found on this island (Rundell 2010).
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:This is a ground dwelling snail found in moist lowland forests.
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: This species is not utilized.

Threats [top]

Major Threat(s):

This sub-species is threatened by destruction and modification of native lowland forest. Therefore it is not surprising that the area of occupancy of the species has been greatly reduced since World War II, when much of the island’s forest was decimated by 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).

Conservation Actions [top]

Conservation Actions:

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, is also urgently needed. The Palau Conservation Society has been supportive of recent land snail survey work in Palau.

Classifications [top]

1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability: Suitable  major importance:Yes
1. Land/water protection -> 1.1. Site/area protection

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education
5. Biological resource use -> 5.3. Logging & wood harvesting -> 5.3.5. Motivation Unknown/Unrecorded
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

6. Human intrusions & disturbance -> 6.2. War, civil unrest & military exercises
♦ timing: Past, Unlikely to Return ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Past Impact 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

1. Research -> 1.2. Population size, distribution & trends

Bibliography [top]

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: (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 constricta ssp. constricta. In: The IUCN Red List of Threatened Species 2012: e.T198784A2534830. . Downloaded on 30 November 2015.
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