Margarya mansuyi: Yilong Lake, Shiping County, Yunnan Province, China, 61.6mm., 1985.
The « Mansuy's Margarya » is a fascinating freshwater snail with a peculiar shift in coiling in the earlier whorls and an attractive keeled form. A member of genus Margarya which contains perhaps the most striking viviparids of all. All are endemic to lakes in Yunnan Province, China; and this species has been recorded in history from Dianchi Lake, Xinyun Lake, Qilu Lake, Datunhai Lake, and Yilong Lake. It is classified as Endangered under the IUCN Red List and Vulnerable under the Chinese Red List due to threats from water extraction, industrial pollution, and tendency of smaller lakes to dry out. It is certainly already extinct in Yilong Lake and probably also in Dianchi Lake and Datunhai Lake, leaving only two surviving known populations. It is thus a rare species, especially in the international shell trade. The same threat is posed to all Margarya species, some of which are already considered to be completely extinct. A wide-range of feeding methods including grazing, detritus feeding, and filter feeding are used by Margarya species. A little-varied species except slight variability in elongateness and strength of keels, its average shell length is around 60mm. while giants occasionally exceed 80mm.