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ABSTRACTHebeloma parvisporumis described as new and placed within H. sect. Porphyrospora. This mushroom is sold as an edible in markets of Laos under the local name “wai khom.” Hebelomasect. Porphyrosporais discussed and expanded to include the species formerly included in the genus Anamikaand recently transferred to Hebeloma. Hebelomasect. Porphyrosporacurrently comprises 16 species, 14 of which are known only from the western Pacific and Indian subcontinent. All species in this section share the character of having red-brown spores when fresh, atypical for other sections of Hebeloma, which causes the lamellae to be red-brown. However, this red-brown color fades when the material is dried. The close links, morphologically and molecularly, between H. parvisporumand other members of H. sect. Porphyrospora, particularly H. victoriense, are shown.

Genes encoding the cellobiohydrolase enzyme (CBHI), designated as cbhI, were isolated from the basidiomycetes Auricularia fuscosuccinea, Pleurotus giganteus, P. eryngii, P. ostreatus, and P. sajor-caju. Initially, the fungal genomic DNA was extracted using a modified cetyltrimethyl ammonium bromide (CTAB) protocol and used as a DNA template. The cbhIgenes were then amplified and cloned using the pGEM-T Easy Vector Systems. The sizes of these PCR amplicons were between 700~800 bp. The DNA sequences obtained were similar showing high identity to the cbhIgene family. These cbhIgenes were partial consisting of three coding regions and two introns. The deduced amino acid sequences exhibited significant similarity to those of fungal CBHI enzymes belonging to glycosyl hydrolase family 7.

A well resolved phylogeny of the Agaricaceae based on partial rpb2 sequences is presented from a wide geographic and systematic sampling of the family and compared to phylogenies based on nrLSU and tef1 sequences. A smaller dataset of the family focusing on the Agaricusclade of nrITS sequences and a combined dataset were used to determine the position of several white-spored taxa from northern Thailand. Two new genera are described from Thailand. Coniolepiotaaccommodates Lepiota spongodes, a gray-lilac-purple floccose white-spored species with a wide distribution in tropical Asia; Eriocybehas a white wooly felt-like covering of pileus and stipe, white spores and is described with one new species E. chionea, so far known only from northern Thailand. These new genera are closely related to three genera with colored spores (viz. Agaricus, Heinemannomycesand Clarkeinda) and not to other white-spored taxa.