Oncomelania hupensis

Oncomelania hupensis is a species of very small tropical freshwater snail, an aquatic gastropod mollusk in the family Pomatiopsidae. Oncomelania hupensis has been found in China, Taiwan, and also in Japan, Philippines, and Indonesian island of Sulawesi. Over the past a few decades, the taxonomy of Oncomelania hupensis has been a dispute due to the variation in morphological characters such as shell sculpture, operculum etc. Phenotypically, Oncomelania hupensis can be separated into ribbed- and smooth- shelled morphotypes. In China, the typical morphotype of Oncomelania hupensis is ribbed-shelled, and its distribution is restricted to Yangtze River basin. Smooth-shelled snails are also distributed in mainland China, but are considered as the same species and subspecies of Oncomelania hupensis. Oncomelania hupensis reported in other Far East countries are smooth-shelled, and have been considered either as subspecies of Oncomelania hupensis or independent species in this genus. There are 4 subspecies of Oncomelania hupensis in China: hupensis, robertsoni, tangi and guangxiensis. Genetic confirmation of thsese four Chinese subspecies: Based on shell form, biogeographical and allozyme data, Davis et al. (1995) distinguished 3 subspecies of the Oncomelania hupensis in mainland China. However, Zhou et al. (2008) separated the Oncomelania hupensis guangxiensis out from Oncomelania hupensis tangi based on allozymes and amplified fragment length polymorphism (AFLP), which was verified recently by Li et al. with internal transcribed spacer (ITS) and 16S fragments. It may also be possible that continuous control efforts, such as routine molluscicides in China, which have been used to control snails for about fifty years, might have imposed some effect on population genetics of these snails. The complete mitochondrial genome of Oncomelania hupensis has been released in 2010.