Morphological variability of Fomes fomentarius basidiomata based on literature data

Currently two morphological species of the genus Fomes (Polyporaceae, Basidiomycota) are known: F. fomentarius (L.) Fr. and F. fasciatus (Sw.) Cooke. Both species are very important in the decomposition of wood and in the nutrient cycling in forest ecosystems. Moreover, F. fomentariusis also known as a source of medicinal and nutraceutical products. Recently the existence of three separate ITS lineages/sublineages among F. fomentarius strains has been clearly established - A1 (the strains isolated from North America), A2 (only from Europe) and B (from Europe and Asia). In this review the current knowledge of the morphological variability of F. fomentarius basidiomata has been summarized in respect of the reliable separation of its lineages/sublineages. Micro- and macrofeatures and geographic variability of the basidiomata have been described. Morphological traits of the F. fomentarius basidiomata can vary due to geographical distribution. These phenotypic differences can be based on the presence of several groups or interactions between the genotype and environment. However, no clear differences between basidiomata, useful for reliable separation of the lineages/sublineages, have been observed so far. A recent description in North American Fomes research articles is based on basidiomata of the A1 sublineage. It is most possible that the descriptions in European literature are based on basidiomata of two other lineages/sublineages and thus we cannot discriminate between them. In the future a detailed study of the macro- and microtraits - pileus and pore surface colors, basidioma size, depth of tube layer, and basidiospore size - is therefore proposed for reliable separation of the lineages/sublineages of F. fomentarius.