Abstract
Specimens of the genus Amanita, collected from northern Thailand and deposited in the fungal herbarium of Chiang Mai University and some overseas herbaria were studied. Twenty-five taxa, including eighteen new to Thailand, are described briefly. A key to species is provided. The new records for Thailand are A. alboflavescens, A. avellaneosquamosa, A. chepangiana, A. clarisquamosa, A. flavipes sensu lato, A. fritillaria, A. fuliginea, A. hongoi, A japonica, A. manginiana sensu W.F. Chui, A. obsita, A. ovalispora, A. pseudoporphyria, A. rubrovolvata, A. sinensis, A. sinocitrina, A. subglobosa, and A. virgineoides. A type study of A. pudibunda is included. Amanita frostiana sensu R. Heim is proposed to be properly diagnosed as A. rubrovolvata.