Abstract
Three new Mitrephora species (Annonaceae), M.langsuanensis sp. nov., M.sirindhorniae sp. nov. and M.sukhothaiensis sp. nov., are described from Thailand. Mitrephoralangsuanensis resembles M.macclurei, but its leaves have more secondary veins, and its flowers have more carpels, with yellow-and-pink striped outer petals with a margin that becomes undulate with age. Mitrephorasirindhorniae resembles M.tomentosa, but has larger sepals and petals, longer flowering pedicels, and shorter monocarp stipes, with monocarps that have a longitudinal ridge. Mitrephorasukhothaiensis is distinct from its Thai congeners in having outer petals that reflex at maturity and inner petals with a pair of appendages on the margin adaxially. The addition of these three new taxa raises the total number of Mitrephora species in Thailand to 14. An identification key for Thai species is provided.