A monograph of Micropsalliota in Northern Thailand based on morphological and molecular data

Using a combination of morphological and molecular data, the genus Micropsalliota is shown to represent a monophyletic lineage in the Agaricaceae sister to Hymenagaricus. Features that distinguish the genus from Agaricus and allied genera include usually small, gracile basidiomes with a membranous partial veil, dextrinoid basidiospores with an apically thickened endosporium and lack of a germ pore, capitate or subcapitate, conspicuous cheilocystidia, and incrusted pileipellis hyphae that turn green in ammonia solution. We provide a monographic treatment of 23 taxa of Micropsalliota from Northern Thailand, of which 13 taxa represent new distribution reports for Thailand and 10 represent new taxa, including M. allantoidea, M. bifida, M. furfuracea, M. lateritia var. vinaceipes, M. megarubescens, M. megaspora, M. pusillissima, M. rubrobrunnescens var. rubrobrunnescens, M. rubrobrunnescens var. tibiicystis, and M. suthepensis. Included in this monograph are comprehensive descriptions, illustrations of micromorphological features, photographs of basidiomes, comparisons with allied species, phylogenetic trees inferring relationships amongst Thai species based on nrITS and nrLSU sequence datasets, and a key to aid in diagnosis.