Abstract The lycaenid genus Phengaris (s. str.) from mainland China is briefly characterized, and a short identification key presented. Phengaris xiushani sp. n. is described and illustrated from northwestern Yunnan. The new species is similar to P. daitozana from Taiwan with respect to the wing maculation ina whitish upperside and much smaller spots on the underside. Genitalia features are similar to Phengaris (Maculinea) nausithous from the western Palaearctic region. The type specimens are kept in the Insect Collection, South China Agricultural University, Guangzhou, China (SCAU), and the “Senckenberg Museum fur Tierkunde” in Dresden, Germany (MTD).