Molecular systematics of Woswasia atropurpurea gen. et sp. nov. (Sordariomycetidae), a fungicolous ascomycete with globose ascospores and holoblastic conidiogenesis

The monotypic genus Woswasia is described for wood-inhabiting and mycotrophic fungi classified in the Sordariomycetidae. It is characterized by unicellular, hyaline, globose to ellipsoid, verruculose ascospores; unitunicate long-stipitate asci with an apical annulus staining blue in aqueous cotton blue and perithecia with a long neck immersed in a stroma exhibiting a conspicuous pH-dependent color reaction. In vitro, it produces branched subhyaline to hyaline conidiophores with terminally arranged sympodial conidiogenous cells and holoblastic hyaline conidia. The remarkable morphological similarity of Woswasia to Amplistroma of the Amplistromataceae, although suggestive of a close relationship, was not confirmed by molecular data. Phylogenetic analysis based on two functional ribosomal genes (large and small subunits of the nuclear rDNA) and one protein-coding gene (second largest subunit of RNA polymerase II) supports the placement of Woswasia in the Sordariomycetidae incertae sedis. Woswasia atropurpurea, the type and only species of the genus, groups within a large heterogeneous clade containing other small or monotypic genera of wood-inhabiting saprobic fungi, which are distantly related and of which the majority lacks an ordinal or familial affiliation. Within the clade a relationship of Woswasia to the freshwater genus Cyanoannulus is suggested.