Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Architaenioglossa Viviparidae

Scientific Name: Margarya monodi
Species Authority: Dautzenberg & Fischer, 1906
Margarya melanioides subspecies monodi Dautzenberg & Fischer, 1906

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(i,ii,iii,iv,v) ver 3.1
Year Published: 2009
Date Assessed: 2008-03-28
Assessor(s): Jiang, Y., McIvor, A., Aldridge, D. & Di, L.
Reviewer(s): Smith, K., McIvor, A. & Seddon, M.B.
Margarya monodi is found in only part of Lake Dianchi and is declining. It is harvested alongside M. melanoides and presumably is declining at the same rate. The species is assessed as Critically Endangered under criterion B as it is found in only one location (a single pollution event can affect the whole lake) with an estimated extent of occurrence of less than 50 km² (one small part of the lake), and there is continuing decline in this snail's range, habitat quality, number of locations and population size. It is not found in Qingshuihe river, from where it was previously known, and there is habitat quality is declining due to pollution, and in population size due to overharvesting.

Before the 1980s, Margarya species were the main commercial snails collected from Lake Dianchi and Lake Er-hai: one person could collect 20 kg of snails per day. Recently, one person can only collect 2 kg per day during the open fishing season. The populations of snails in this genus have reduced by 90% in the past three generations. Ten years ago people collected snails in the east of the lake, but there are no longer any snails remaining there.

Geographic Range [top]

Range Description: This species is endemic to Lake Dianchi (292 km²) in Yunnan province, China. There is also a record from Qingshuihe River but surveys in June 2008 by Du Lina were not able to find it here. In Lake Dianchi, the species is found only in the part of the lake that is near the outflow, representing an area of about one sixth of the lake area (approximately 50 km²).
Countries occurrence:
China (Yunnan)
Estimated area of occupancy (AOO) - km2: 50
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 50
Continuing decline in extent of occurrence (EOO): Yes
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
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 [top]

Population: This snail is not abundant in its only known location.
Current Population Trend: Decreasing
Additional data:
Continuing decline of mature individuals: Yes

Habitat and Ecology [top]

Habitat and Ecology: It is found only in the part of Lake Dianchi that is near the outflow, so it may be a species that needs slightly flowing water.
Systems: Freshwater
Continuing decline in area, extent and/or quality of habitat: Yes

Use and Trade [top]

Use and Trade: This species is harvested for both food and medicine.

Threats [top]

Major Threat(s): The main threats affecting this snail are organic and inorganic pollution; overfishing (the species is harvested for food and medicine); habitat degradation; introduced predatory fish species; and dyke construction.

Conservation Actions [top]

Conservation Actions: Currently there are no conservation measures in place for this species. Fisheries management of harvest levels, and perhaps ex-situ propagation programmes are required.

Citation: Jiang, Y., McIvor, A., Aldridge, D. & Di, L. 2009. Margarya monodi. The IUCN Red List of Threatened Species 2009: e.T168214A6466980. . Downloaded on 10 October 2015.
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