Abstract

Shells and operculums of eight species of Bithyniidae, Bithynia leachi, B. tentaculata, B. siamensis, B. misella, B. kiusiuensis, Gabbia australis, B. manchourica and a Bithynia sp. collected from Nepal, were observed, There is no morphological difference between korean populations of B. misella and a Japanese popualtion of B. kiusiuensis. And the shells of these species were simialr to the other Bithynia species rather than Australian Gabbia. The coordinate of the starting point of nuclear spire of operculum(SPN)was species specific and this value had very limited range within a species. The result suggested that Korean and Japanese populations of B. misella and B. kiusiuensis are synonym and the coordinate of SPN will be a useful character in sytematics of operculated snails.