Chiang Mai Journal of Science

 As part of our efforts of study the saprobic mushrooms in Asia we have collected numerous taxa of the genus Agaricus in northern Thailand. It is likely that more than 40 new species occur in this region and many are potentially edible or medicinal. A recent phylogenetic study revealed that most species of this region belong to exclusively tropical clades of which the largest one, TR I, was suspected to represent section Brunneopicti. In this paper we introduce two new species as Agaricus chiangmaiensis and A. megacystidiatus based on fresh collections in addition to collections previously classified in two putative species of clade TR I. The new species are described and illustrated with line drawings and photographs and compared with similar taxa. Agaricus chiangmaiensis shows affinities with A. brunneopictus. However, taxonomical investigation on more species will be necessary to characterize the clade TR I and to clarify to what extend it would represent the section Brunneopicti.