Yangtsunghai Lake, Yunnan Province, China, 50.0mm., 2013.
Margarya yangtsunghaiensis is a very attractive freshwater snail endemic to a single small lake with surface area of 32km2 -- the Yangtsunghai Lake in Yunnan Province, China. It is listed on both IUCN Red List and Chinese Red List as Critically Endangered; some claim it may already be extinct. This is because the last official records of live specimens were back in 1949, and supposedly no live specimens were found in recent surveys of the lake. Given this background it is unsurprisingly a rare shell on the market, although it is puzzling that apparently live taken specimens claiming to be taken in recent years are sometimes seen for sale. Viviparids are known for having a wide-range of feeding methods, including grazing, detritus feeding, and filter feeding; genus Margarya is no exception. It lives across all depths of Yangtsunghai Lake, the maximum depth of which is about -30m. Typical shell length around 45mm., very large specimens may approach 60mm. The genus Margarya includes some of the most amazingly sculptured freshwater gastropods of all, and once common enough to be used for food by local people. Nowadays however, unfortunately most species of this small (11 species) genus endemic to Yunnan Province are in sharp decline or alread extinct due to anthropogenic pollution of the lakes they inhabit since the 1980s. This continues today and Yangtsunghai Lake, for example, was affected by a large-scale Arsenic pollution from a local fertilizer factory in 2008.