Hymenagaricus saisamornae sp. nov. (Agaricales, Basidiomycota) from Northern Thailand

A new species of agaricomycetes, Hymenagaricus saisamornae is described herein based on collections from northern Thailand. This species is characterized by its small-sized basidiomata, a squamulose pileus consisting of hymeniform cells, yellowish brown basidiospores and an absence of pleurocystidia and clamp connections. However, it is clearly distinguishable from H. alphitochrous by the smaller pileus and narrower hymeniform cells of the squamulose pileus. Molecular phylogenetic analyses, based on a combination of the internal transcribed spacers (ITS) and the large subunit (nrLSU) of the nuclear ribosomal DNA, also support the finding that H. saisamornae is distinct from other known species within the genus Hymenagaricus. A full description, color photographs, illustrations and a phylogenetic tree showing the position of H. saisamornae are provided.