Two new Fagus-feeding notodontids, i.e. Syntypistis taipingshanensis Wu & Hsu sp. n. and Pheosiopsis seni Wu & Hsu sp. n. are recently discovered from the relic Fagus forests in northeastern Taiwan. Based on the genitalia structures, the closely relatives of two new species are S. melana Wu & Fang, 2003 and P. albalienata Kishida & Kobayashi, 2005, respectively, both occurring in the Fagus forests of Southern China.