|Scientific Name:||Samoana burchi Kondo, 1973|
|Taxonomic Notes:||High altitude species in the wild misidentified as S. attenuata but recently reclassified as S. burchi after molecular analysis (O'Foighil pers. comm.)|
|Red List Category & Criteria:||Critically Endangered B2ab(iii) ver 3.1|
|Reviewer(s):||Barker, G., Cowie, R., Triantis, K., García, N. & Pippard, H.|
The species has only been recorded from two distinct and fragmented locations at Mount Aorai and Atara. Both subpopulations are directly threatened by the invasive predator E. rosea. The area of occupancy has been estimated to be approximately 8 km², and there is evidence of a continuing decline in this area of occupancy, as well as in the quality of the habitat due to invasive species and habitat modification. The species is listed as Critically Endangered.
Continued biosecurity vigilance is critical to prevent further invasive species establishments in this species' habitat. Surveys to determine the current distribution of this species and population size, status and trends are also recommended, as is monitoring of habitat and threats from invasive predators.
|Previously published Red List assessments:|
|Range Description:||This species is endemic to the montane forests of the island of Tahiti, Society Islands. According to Kondo (1973), it was first sampled (but unidentified) in the early 1930s between 1,300 and 1,500 m altitude on the slopes of Mt. Aorai (Tahiti Nui, elevation 2,066 m). In 1970, it was sampled at an altitude of 985 m in the Haoma highlands (Tahiti-Iti), the type locality. The linear distance between the Tahiti-Nui and Tahiti-Iti sites is 35 km (Kondo 1973). |
In 2005, Trevor Coote biopsied additional specimens on Mt. Aorai and at approximately 1,000 m altitude on Mt. Atara (Tahiti-Iti) that were positively identified as Samoana burchi using molecular markers as well as diagnostic shell characters (Lee et al. 2009). The species therefore survives in at least one montane forest location in each of the two Tahitian peninsulas, being absent from the intervening low altitude habitat. However, we know very little concerning the actual population size or the extent of its distribution throughout Tahitian montane forests.
Native:French Polynesia (Society Is.)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No specific information on population is available. It is confirmed as existing in two montane locations: Mt. Aorai (Tahiti-Nui) and Mt. Atara (Tahiti-Iti).|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||The species was recorded from high altitude cloud forest.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||0-3|
|Congregatory:||Congregatory (and dispersive)|
|Use and Trade:||There is no known use or trade.|
The primary threat to this species is posed by the introduced predatory land snail Euglandina rosea. The predator has extirpated most Tahitian valley partulid populations since its introduction in 1975 (Coote and Loève 2003, Coote 2007) and extends at least to an altitude of 1,400 m into the montane forests (Lee et al. 2008 and 2009, Gargominy 2008). Lower elevation populations are therefore directly exposed to the predator, however, it is not clear how serious that exposure is in reality. Persistence of montane Partula otaheitana populations in the presence of E. rosea (Lee et al. 2009) implies that the predator may be relatively ineffective at these altitudes, as predicted by Gerlach (1994), and that native taxa may experience an altitudinal refuge (Gargominy 2008, Lee et al. 2009). Montane Tahitian habitats are relatively inaccessible and undisturbed; but there is some loss of habitat due to anthropogenic action, especially fire (Gargominy 2008).
|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, and invasive species, is also urgently needed|
|Citation:||O'Foighil, D. 2012. Samoana burchi. The IUCN Red List of Threatened Species 2012: e.T168195A1185169.Downloaded on 18 September 2018.|
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