Tretomyces gen. novum, Byssocorticium caeruleum sp. nova, and new combinations in Dendrothele and Pseudomerulius (Basidiomycota)

One new genus, Tretomyces K.H. Larss., Kotir. & Saaren., and two new species, Tretomyces microsporus Kotir., Saaren. & K.H. Larss., and Byssocorticium caeruleum Kotir., Saaren. & K.H. Larss. are described and illustrated. Three new combinations, Tretomyces lutescens (J. Erikss. & Ryvarden) K.H. Larss., Kotir. & Saaren., Dendrothele minutissima (Hohn. & Litsch.) Kotir., K.H. Larss. & Saaren. and Pseudomerulius montanus (Burt) K.H. Larss., Kotir. & Kulju, are proposed.