Taxonomy and phylogeny of white-rot polypores: case studies in Hymenochaetales and Polyporales (Basidiomycota)

This thesis deals with genealogy of polypores. Polypores are a form group of basidiomycete fungi (Basidiomycota). Their underside is formed of fused tubes. As a form group polypores can be compared to trees in that neither all polypores nor all trees are related despite their similar appearance. The use of DNA is revolutionising our understanding of how polypores are related. The classification formerly in use was based on fruiting body characters, and has turned out to be highly unnatural from the perspective of genealogy. In the thesis work I studied evolutionary history of several polypore genera using DNA and traditional methods.

Main results of the study are related to the polypore genus Antrodiella, which includes about 70 species. Antrodiella turned out to be a heterogeneous assemblage of species. Species currently included in the genus belong to two orders and to a minimum of 13 genera. Two Antrodiella species new to Finland were found during the study (A. ichnusana and A. leucoxantha). Three new polypore genera were also described (Obba, Sidera and Sebipora).

Majority of Antrodiella belong to the family Steccherinaceae, which was redefined in this study. In addition to polypore genera, Steccherinaceae includes genera with fruiting bodies that have a spinose (hydnoid) underside. Typically poroid and hydnoid fungi are classified in separate genera regardless of their microscopic similarity. This study focused on the evolutionary relationship between hydnoid and poroid species within Steccherinaceae. The results show that poroid and hydnoid fungi mostly seem to belong to separate genera, but there are also exceptions (Antrodiella, Metuloidea and Steccherinum). Almost all genera that were defined with the aid of DNA could be characterised with fruiting body and microscopic characters.

The results have wider implications in polypore classification by showing which characters are significant in classifying polypores. Increased information about species diversity and genealogy produced in this study benefits ecological research and assessments about endangered species. The DNA-library created during the study is in use for identification of polypores. The results can also be utilised in the search for biotechnological applications from polypores, since characters that are interesting from the biotechnological perspective often follow polypore genealogies.