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Cystolepiota Singer is rarely studied in Southeast Asia; here, we survey and describe three new species of Cystolepiota from tropical Laos and Thailand. Cystolepiota pyramidalis is related to C. fumosifolia (Murrill) Vellinga and C. pseudofumosifolia M.L. Xu & R.L. Zhao, but it is distinguished by pale to pastel yellow lamellae. Second, Cystolepiota thailandica differs from other members in the genus by the greyish-orange granulose or powdery pileus and stipe covering made up of globose to subglobose and sphaeropedunculate elements. Furthermore, Cystolepiota rhodella is characterized by the pink-violet granulose covering of the pileus and stipe and white lamellae with distinctly violet edges. Each species is provided with a full description of the morphological characters, photos in situ, line drawings of the microcharacters, discussion of related and similar species, and molecular data. [ABSTRACT FROM AUTHOR]

In our ongoing research on lepiotaceous taxa (Agaricaceae s.l.) in Laos and northern Thailand, we focus here on Chlorophyllum, Clarkeinda, Macrolepiota, Pseudolepiota, and Xanthagaricus. Collections were obtained from various habitats, including agricultural habitats, grasslands, and rainforests. A total of 12 taxa were examined and investigated. Of these 12, two are new for science; viz. Xanthagaricus purpureosquamulosus with brownish-grey to violet-brown squamules on a pale-violet to violet background; it shares the pileus color with X. caeruleus and X. ianthinus, but differs in other characters; and Macrolepiota excelsa, rather similar to M. procera but related to M. detersa. Two species, Pseudolepiotazangmui and Xanthagaricus necopinatus are recorded for the first time in Thailand. Four species of Chlorophyllum and a total of four species of Macrolepiota were found, viz., C. demangei and C. hortense with white basidiospores, C. molybdites and C. globosum with green basidiospores, M. detersa, M. dolichaula, the new M. excelsa, and M. velosa. Another rather common striking species is Clarkeinda trachodes, with yellow-green basidiospores. Each species is described in detail, with color photographs and line drawings. Phylogenetic analyses based on internal transcribed spacer (nrITS) region, the large subunit nuclear ribosomal (nrLSU) DNA and RNA polymerase II second largest subunit (rpb2) genes provide evidence for the placement of the species covered. [ABSTRACT FROM AUTHOR]