Abstract
A new ectomycorrhizal fungus, Gyrodon suthepensis, is described based on collections from northern Thailand. It can be distinguished from the previously described Gyrodon species by the morphological characteristics. The molecular phylogenetic analyses of the internal transcribed spacers (ITS) and large subunit (LSU) of the nuclear ribosomal DNA confirms the position of the new species within the family Paxillaceae. The full description, color photographs, illustrations and the phylogenetic tree to show the position of G. suthepensis are provided. The new species grows in association with the ectomycorrhizal tree Betula alnoides, and the morphology and anatomy of mycorrhizas are described. Moreover, the identification of mycorrhizal association of G. suthepensis was confirmed by molecular methods.