| Bogs store vast amounts of carbon (C) due to slow decomposition of Sphagnum. Global warming could increase decomposition and C mobilization. Lignin- and cellulose-degrading fungi are primary decomposers of Sphagnum but their diversity and temperature responses are poorly known. Psychrotolerant species of Myxotrichaceae ( Ascomycota) were abundant from peat and wood bait. Oidiodendron maius was the most common species on moist incubated peat while Geomyces pannorum was most abundant on peat cultured on Mycosel RTM agar and on bait in moist chambers and on MycoselRTM agar. Six Oidiodendron species and two Pseudogymnoascus species were isolated from bait. Their abundance suggests they may be important decomposers of peat.;In vitro assessments suggest Myxotrichaceae can decompose Sphagnum at current temperatures. Most species degraded cellulose and soluble phenolics and caused 0-50% mass loss of Sphagnum. In contrast, two basidiomycetes degraded cellulose and insoluble phenolics and caused 0-35% mass loss. The Myxotrichaceae eroded the Sphagnum leaf cell walls in a pattern resembling simultaneous white rot of wood, while the decay caused by the basidiomycetes resembled preferential white rot. These results indicate Myxotrichaceae can release C and nutrients from peat, playing an important role in nutrient cycling. Their importance may be increased by their formation of mycorrhizal associations with dominant peatland plants.;Accurate ecological assessment of these species required taxonomic clarification. Morphology and physiology, including BiologRTM FF profiles, distinguished 25 Oidiodendron species, including O. fimicolum, a new species from mushroom compost, and two unnamed species from Perryvale Bog. Oidiodendron fuscum was reinstated as the generic type, O. citrinum was transferred to O. maius as O. maius var. citrinum, and O. scytaloides, O. reticulatum, and O. ramosum were shown to be synonyms of O. chlamydosporicum, O. hughesii , and O. setiferum respectively, and O. robustum and O. terrestre were excluded. Pseudogymnoascus appendiculatus and P. verrucosus were described from Perryvale Bog and a key was provided to four taxa in Pseudogymnoascus. The new species had characters intermediate between Pseudogymnoascus and Gymnostellatospora, prompting a re-evaluation of these genera and anamorphs in Geomyces. ITS sequence data support the distinction between Gymnostellatospora and Pseudogymnoascus but indicate that Geomyces is polyphyletic. |
