Pholiota mucigera (Agaricales), a new species from a boreal old-growth forest

A new species of Agaricales (Basidiomycetes), Pholiota mucigera Holec & Niemela, is described. It is characterized by fairly large size and almost white, a cup covered with very thick slime. No scales are found on the pileus surface. In the microscope the species can be identified by the absence of cystidia; spores an ca. 5.1-6.2 x 3.3-4 mu m and lack the germ pore. The species was found in a virgin spruce-dominated forest in Finland, growing on fallen Populus tremula. Differences between related species of Pholiota are discussed.