Aaadonta constricta 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Stylommatophora Endodontidae

Scientific Name: Aaadonta constricta
Species Authority: (Semper, 1874)
Infra-specific Taxa Assessed:
Edodonta constricta Semper, 1874
Taxonomic Notes:

There are three subspecies, namely babelthuapi Solem, 1976; constricta s. str.; and komakanensis Solem, 1976

Assessment Information [top]

Red List Category & Criteria: Endangered B1ab(i,ii,iii)+2ab(i,ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2011-12-13
Assessor(s): Rundell, R.J.
Reviewer(s): Barker, G. & Seddon, M.
Facilitator/Compiler(s): Pippard, H.
The species is listed as Endangered. It is found in very small numbers at five localities among five islands over a total area of < 1 km2. There is a continuing decline in area of occupancy with a decline in quality and extent of habitat. Humans frequently visit three of the five islands, and there are permanent villages on the remaining two of the five islands (i.e. Peleliu, where most of the live snails were found - seven live individuals) and Babeldaob.
Previously published Red List assessments:
1996 Data Deficient (DD)
1994 Vulnerable (V)

Geographic Range [top]

Range Description:

This is a minute ground-dwelling snail that was historically known from the following localities in Palau: a single locality on the island of Babeldaob (Babelthuap),  a single locality on Ngemelis (subsp. babelthuapi); several localities on Peleliu (Beliliou); where a total of 82 specimens were collected by Y. Kondo in 1936 (Solem 1976) (subsp. constricta); and the island of Koror (Oreor), where it was collected at a single locality in 1936 by Y. Kondo (Solem 1976) (subsp. komakanensis). The historical geographic range of this species was less than 10 km2. The area of occupancy for this species is now thought to be <1 km2, as recent surveys yielded very few specimens from only five localities in native forest, with an area less than 1 km2.

Countries occurrence:
Estimated area of occupancy (AOO) - km2: 1
Continuing decline in area of occupancy (AOO): Yes
Estimated extent of occurrence (EOO) - km2: 10
Continuing decline in extent of occurrence (EOO): Yes
Number of Locations: 5
Lower elevation limit (metres): 1
Upper elevation limit (metres): 200
Range Map: Click here to open the map viewer and explore range.

Population [top]


Nineteen live snails of this species, from five different islands, have been found in recent years. It is no longer known from the single Babeldaob locality, nor Ngemelis, where the species was earlier reported (Rundell 2005, R.J. Rundell 2005 unpublished data). However, three live shells were found in Ngatpang State on Babeldoab in 2003 (Rundell 2005, R.J. Rundell 2003 unpublished data). Seven live (and three dead) shells were found on the island of Beliliou in 2005 (Rundell 2010). No shells (live or dead) have been found in recent years on Koror, despite surveys on this island in 2003, 2005 and 2007 (R.J. Rundell 2007 unpublished data, Rundell 2005 and 2010). Two live shells were found on Ngeruktabel in 2003 (Rundell 2005, R.J. Rundell 2003 unpublished data). In 2005, five live shells were found on Omekang, and 2 live shells were found on Ulong (Rundell 2010, Rundell 2005, unpublished data).

Despite the fact that live snails of this species have been found on five different islands, the main concern is that the number of live snails on these islands appears to be very low, particularly in comparison with historical records. For example, on Peliliou, 82 live specimens were collected by Y. Kondo in 1936 (Solem 1976), but recently only seven live snails were found on this island. The species is presumed extinct from Koror (the most heavily populated island), based on recent surveys (e.g. Rundell 2010, Rundell 2007 unpublished data). The main concern for the species on the island of Babeldaob is that only three live specimens have been found, despite the fact that this large island has been widely surveyed for land snails (e.g. Rundell 2010). Additionally, Babeldaob’s native forest is highly threatened by development (e.g. due to the recent completion of the Compact Road).

Current Population Trend: Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology: This species is known from tropical moist forest.
Systems: Terrestrial
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 species is threatened by destruction and modification of native lowland forest. This threat is imminent on the island of Babeldaob, which is currently undergoing significant change due in part to the completion of the paved Compact Road around the island, which is facilitating development of previously remote locations (Cowie et al. 1996). It is also perhaps not surprising that the overall area of occupancy of the species has been greatly reduced since World War II, when much of Peleliu’s forest was for example 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: This species is not protected. Surveys to determine the current distribution of this species and its population size, status and trends are recommended.

Citation: Rundell, R.J. 2012. Aaadonta constricta. The IUCN Red List of Threatened Species 2012: e.T4A3013586. . Downloaded on 26 November 2015.
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