|Scientific Name:||Margarya mansuyi|
|Species Authority:||(Dautzenberg & Fischer, 1906)|
Margarya melanoides subspecies mansuy Dautzenberg
|Taxonomic Notes:||The other names are as follows: Margarya melanioides var. Mansuyi .|
|Red List Category & Criteria:||Endangered B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1|
|Assessor(s):||Jiang, Y., Di, L., Aldridge, D. & McIvor, A.|
|Reviewer(s):||McIvor, A., Smith, K. & Seddon, M.B.|
Margarya mansuyi is known to be present in Lake Xingyun (34 km²) and Lake Qilu (37 km²) and was found in both lakes in recent years; it is certainly now extinct in Lake Yilong and has not been found in recent surveys of Lake Datunhai and Lake Dianchi. Its current known range area therefore
falls within the thresholds for Endangered under criterion B (for the two lakes—two locations—where the species' presence is currently confirmed). The main threats to the species include water abstraction, pollution and a tendency for these small lakes to dry out.
This species was assessed by Liu Yueing and Wu Min as Vulnerable for the Chinese Red List (2004). Their assessment was also based on the criterion B, but eight locations were estimated for the species. Three of these locations, however, were errors and recent survey data shows that the species is now extinct or likely extinct in three more of these lakes (lakes Yilong, Datunhai and Dianchi).
|Range Description:||This species occurs in Yunnan Province, China, where it occurs in Lake Xingyun (34 km²) and Lake Qilu (37 km²). The species was found to still be present in these lakes in 2006 and 2007 respectively. Previously it was known from Lake Yilong, Lake Dianchi, and Lake Datunhai (also called Lake Datun). Relatively recently it was known from Lake Yilong (32 km²) and Lake Datunhai (12 km²). However in 1983, Lake Yilong dried up for about two months, and the species is now considered extirpated from this lake. Lake Datunhai did not dry up but became very shallow. Both these lakes were surveyed in 2006 and this snail was not found (Du Lina, pers. comm. 2008), and another survey of Lake Datunhai in May 2008 by Du Lina also did not find it, so it is probably no longer present in there. Du Lina also surveyed Lake Dianchi in May 2008 and could not find the species; it has probably also been extirpated from there.
The species was previously listed in the China Red List (2004) as also occurring in Lakes Fuxian and Erhai, but Du Lina believes these records to be errors.
|Estimated area of occupancy (AOO) - km2:||0-50|
|Continuing decline in area of occupancy (AOO):||Yes|
|Extreme fluctuations in area of occupancy (AOO):||No|
|Estimated extent of occurrence (EOO) - km2:||71|
|Continuing decline in extent of occurrence (EOO):||Yes|
|Extreme fluctuations in extent of occurrence (EOO):||No|
|Number of Locations:||2|
|Continuing decline in number of locations:||Yes|
|Extreme fluctuations in the number of locations:||No|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The species has been lost from three lakes where it previously occurred. In its current known range it is very rare.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Small lakes.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Congregatory:||Congregatory (and dispersive)|
|Use and Trade:||Shell can be used for buttons, and arts and crafts materials. Mother of pearl can be used for traditional Chinese medicine. Their flesh for human consumption, and for poultry, fish and natural bait. Is also the livestock and poultry feed.|
|Major Threat(s):||Lake Yilong is used to irrigate farmland and water abstraction is a major problem here; the drying up of the lake in 1983 is the likely cause of the species being lost from this lake. Pollution is an ongoing problem. Lake Datunhai (which also previously held a population of this snail) is very small and becomes green each year so it is probably eutrophic; the water level also changes quickly. The small sizes of these lakes makes them very vulnerable to drying out, and if the entire lake dries out the snail population dies. Fish harvesting in the lakes also results in this species being take as bycatch but the snails themselves are not used.|
|Conservation Actions:||None in place. The species is certainly extinct in Lake Yilong, but further surveys are required to confirm whether any individuals remain in lakes Datunhai, Qilu and Xingyun.|
|Citation:||Jiang, Y., Di, L., Aldridge, D. & McIvor, A. 2009. Margarya mansuyi. The IUCN Red List of Threatened Species 2009: e.T166311A6198321. . Downloaded on 26 May 2016.|
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