Cryptic species diversity in polypores: the Skeletocutis nivea species complex

Abstract

We propose a taxonomic revision of the two closely related white-rot polypore species,Skeletocutisnivea(Jungh.) Jean Keller andS.ochroalbaNiemelä (Incrustoporiaceae, Basidiomycota), based on phylogenetic analyses of nuclear ribosomal internal transcribed spacer (ITS) and translation elongation factor EF-1α sequences. We show that prevailing morphological species concepts ofS.niveaandS.ochroalbaare non-monophyletic and we delineate new species boundaries based on phylogenetic inference. We recognise eleven species within the prevailing species concept ofS.nivea(S.calidasp. nov.,S.coprosmaecomb. nov.,S.futilissp. nov.,S.imperviasp. nov.,S.ipuletiisp. nov.,S.lepidasp. nov.,S.nemoralissp. nov.,S.niveasensu typi,S.semipileatacomb. nov.,S.unguinasp. nov.andS.yuchengiisp. nov.) and assign new sequenced epitypes forS.niveaandS.semipileata.The traditional concept ofS.ochroalbacomprises two independent lineages embedded within theS.niveaspecies complex. The Eurasian conifer-dwelling speciesS.cummatasp. nov.is recognised as separate from the North AmericanS.ochroalbasensu stricto. Despite comprehensive microscopic examination, the majority of the recognised species are left without stable diagnostic character combinations that would enable species identification based solely on morphology and ecology.