Phylogenetic and taxonomic studies on the brown-rot fungi Postia and related genera, are carried out. Phylogenies of these fungi are reconstructed with multiple loci DNA sequences including the internal transcribed spacer regions (ITS), the large subunit (nLSU) and the small subunit (nSSU) of nuclear ribosomal RNA gene, the small subunit of mitochondrial rRNA gene (mtSSU), the translation elongation factor 1-α gene (TEF1), the largest subunit of RNA polymerase II (RPB1) and the second subunit of RNA polymerase II (RPB2). Ten distinct clades of Postia s.lat. are recognized. Four new genera, Amaropostia, Calcipostia, Cystidiopostia and Fuscopostia, are established, and nine new species, Amaropostia hainanensis, Cyanosporus fusiformis, C. microporus, C. mongolicus, C. piceicola, C. subhirsutus, C. tricolor, C. ungulatus and Postia sublowei, are identified. Illustrated descriptions of the new genera and species are presented. Identification keys to Postia and related genera, as well as keys to the species of each genus, are provided.

During a survey of cold-adapted fungi in alpine glaciers on the Qinghai-Tibet Plateau, 1 428 fungal isolates were obtained of which 150 species were preliminary identified. Phoma sclerotioides and Pseudogymnoascus pannorum were the most dominant species. Psychrotolerant species in Helotiales (Leotiomycetes, Ascomycota) were studied in more detail as they represented the most commonly encountered group during this investigation. Two phylogenetic trees were constructed based on the partial large subunit nrDNA (LSU) to infer the taxonomic placements of these strains. Our strains nested in two well-supported major clades, which represented Tetracladium and a previously unknown lineage. The unknown lineage is distant to any other currently known genera in Helotiales. Psychrophila gen. nov. was therefore established to accommodate these strains which are characterised by globose or subglobose conidia formed from phialides on short or reduced conidiophores. Our analysis also showed that an LSU-based phylogeny is insufficient in differentiating strains at species level. Additional analyses using combined sequences of ITS+TEF1+TUB regions were employed to further investigate the phylogenetic relationships of these strains. Together with the recognisable morphological distinctions, six new species (i.e. P. antarctica, P. lutea, P. olivacea, T. ellipsoideum, T. globosum and T. psychrophilum) were described. Our preliminary investigation indicates a high diversity of cold-adapted species in nature, and many of them may represent unknown species.

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