Freshwater or semi-freshwater species of Thelidium from Yunnan, China were taxonornically examined: T. luchunense sp. nov. and T. sinense sp. nov. are newly described, and T. minutulum is reported for the first time from China. Descriptions ant) illustrations are provided, as well as a key to the freshwater and semi-freshwater species of Thelidium from Yunnan. aquatic, China, lichens, Thelidium, Verrucariaceae, Yunnan