|Scientific Name:||Margarya bicostata|
|Species Authority:||Tchang & Tsi, 1949|
|Taxonomic Notes:||Tchang-Si and Tsi, Chung-Yen named this species in their 1949 paper, regarding it as a subspecies. Xia (1982) reviewed the Margarya species in Lake Dianchi, and believed this to be a separate species. Xia is followed here.|
|Red List Category & Criteria:||Endangered B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1|
|Assessor(s):||Aldridge, D., Di, L., Jiang, Y. & McIvor, A.|
|Reviewer(s):||McIvor, A., Seddon, M.B. & Smith, K.|
Margarya bicostata was originally assessed for the China Red List by Liu Yueing and Wu Min in 2004 as Endangered based on the B criteria. This more recent assessment agrees with their assessment, although the number of sites where it is believed to be present has been reduced, as further checks have been made on known specimens.
This species used to be common and was found in Lake Dianchi and Lake Fuxian. It is almost certainly no longer present in Lake Dianchi due to the high levels of pollution there. In Lake Fuxian, it was found both near the shore and in the deeper water, but recently it has not been seen at all near the shore. There are some reports from local people that it may still be present in the deeper parts of the lake but this is unconfirmed. The only recent confirmed record is from an artificial pond which is connected to the lake (Du Lina pers. comm. 2006). Therefore there has been a major decline of this species. It is listed here as being present in two locations: Lake Fuxian and the artificial pond connected to the lake.
This species is listed as Endangered under criterion B because of its small range area (both extent of occurrence and area of occupancy are less than 500 km²), its occurrence in only two locations, and continuing decline in the number of subpopulations, range, population size, and habitat quality. It also qualifies as Vulnerable because of its restricted range and current threats. In fact, the species may well qualify for Critically Endangered but data on population size and rate of reduction are lacking to be able to confirm this at present.
Margarya bicostata is endemic to Yunnan Province, China, where it occurs in Lake Fuxian (212 km²) and in an artificial pond connected to the lake (the pond is very small). This species was assessed by Liu Yueing and Wu Min in 2004 for the Chinese Red List who noted it was present in five lakes (Fuxianhu, Qilhu, Xingyunhu, Yilonghu and Erhai). Four of these lakes are closely localised, but the fifth is further away. Du Lina has checked the assessment, and found the other records are in error, and that the species is only found in Fuxian lake (1949) and since then has only been seen in the pond in 2006 (Du Lina pers. comm. 2008).
This species used to be common and was found in Lake Dianchi and Lake Fuxian. It is almost certainly no longer present in Lake Dianchi due to the high levels of pollution there. In Lake Fuxian, it was found both near the shore and in the deeper water, but recently it has not been seen at all near the shore. There are some reports from local people that it may still be present in the deeper parts of the lake but this is unconfirmed. The only recent confirmed record is from an artificial pond which is connected to the lake (Du Lina pers. comm. 2006).
|Estimated area of occupancy (AOO) - km2:||212|
|Continuing decline in area of occupancy (AOO):||Yes|
|Extreme fluctuations in area of occupancy (AOO):||No|
|Estimated extent of occurrence (EOO) - km2:||212|
|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:||This species probably is still present in the deeper waters in the middle of the lake, where people cannot collect it. Local people say they have seen it here. Only one specimen was found in the artificial pond connected to the lake. Therefore it probably is not abundant, but there is not enough information available to confirm this.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Lakes and ponds (artificial). Currently, it lives in deep water, however in the past it was found near the lake shore but according to local people it hasn't been seen there since around the 1980s.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Major Threat(s):||Pollution and invasive predatory fish species. The species is not harvested because its current deep water habitat makes this difficult.|
|Conservation Actions:||None in place. Surveys are required to find out the current status and population levels in lake. If it is still present, then reducing pollution levels and restoring the habitat is necessary, along with raising awareness amongst local people.|
|Citation:||Aldridge, D., Di, L., Jiang, Y. & McIvor, A. 2009. Margarya bicostata. The IUCN Red List of Threatened Species 2009: e.T168212A6466503. http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T168212A6466503.en . Downloaded on 13 October 2015.|
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