Monographic Studies in the Genus Polyporus (Basidiomycotina)

The aim of this dissertation research was an examination of the homobasidiomycete genus Polyporus as currently circumscribed. Emphasis was on addressing the genus by a variety of tools appropriate to modern monographic studies, without producing another worldwide monograph. In addition to morphological examination, which traditionally was the basis of all fungal systematics, mating experiments with monokaryotic cultures, and contemporary phylogenetic tools were used.

For P. alveolaris, P. arcularius, P. badius, P. brumalis, P. ciliatus, P. dictyopus, P. guianensis, P. melanopus, P. tubaeformis, P. tuberaster, P. tricholoma, P. umbellatus, and P. varius a tetrapolar mating system was confirmed. Intercollection mate recognition was tested in P. alveolaris, P. arcularius, P. brumalis, P. ciliatus, P. tubaeformis, P. tuberaster, P. tricholoma, and P. varius. In both P. varius and P. tubaeformis cultures from European and North American collections were found to be compatible. In P. tricholoma, the existence of at least two cryptic biological species entities was found to be contained under the species epithet, whereas in P. alveolaris there may also be cryptic species. The type specimen of P. tricholoma was studied and one of the P. tricholoma cryptic species selected to represent P. tricholoma proper.

Sequence analyses of nuclear ribosomal DNA were utilized to elucidate relationships of Polyporus and allied genera. With large subunit (nLSU) data, the genus Polyporus was found to be non-inclusive under current limits. The infrageneric group Polyporellus was transferred into an emended genus Lentinus, which traditionally was a genus of gilled fungi. The thelephoroid-hydnoid fungus Mycobonia flava was transferred into Polyporus.

Investigation of relationships of infrageneric groups in Polyporus revealed ITS region rDNA template heterogeneity, supported groups seen in nLSU analyses, and was able to differentiate morphological or biological species. Specific primers and RFLP markers for P. tricholoma were evaluated for identification of cryptic species, but were rather successful in uncovering rDNA copy heterogeneity. As a consequence of molecular data and nomenclatural considerations, a new subgenus Favoliporus was proposed to absorb infrageneric groups Favolus and Admirabilis.