Abstract
A new species of agaricomycetes, Clitopilus lampangensis, is described based on collections from northern Thailand. This species was distinguished from previously described Clitopilus species by its pale yellow to grayish yellow pileus with the presence of wider caulocystidia. Molecular phylogenetic analyses, based on the data of the internal transcribed spacers (ITS) and the large subunit (LSU) of the nuclear ribosomal DNA, and the second largest subunit of RNA polymerase II (rbp2) genes, also support the finding that C. lampangensis is distinct from other species within the genus Clitopilus. A full description, color photographs, illustrations and a phylogenetic tree showing the position of C. lampangensis are provided.