<i>Fomitopsis mounceae</i> and <i>F. schrenkii</i>—two new species from North America in the <i>F. pinicola</i> complex

Two new species, <i>Fomitopsis mounceae</i> and <i>F. schrenkii</i> (Polyporales, Basidiomycota) in the <i>F. pinicola</i> species complex in North America, are described and illustrated. Previous molecular phylogenetic analyses identified three well-delimited lineages that represent <i>F. mounceae</i> and <i>F. ochracea</i> from Canada, the Appalachian Mountains, and the northern United States and <i>F. schrenkii</i> from western and southwestern regions of the United States. <i>Fomitopsis pinicola</i> sensu stricto is restricted to Eurasia and does not occur in North America. Morphological descriptions of basidiocarps and cultures for <i>F. mounceae, F. schrenkii</i>, and <i>F. ochracea</i> are presented. The three species are readily differentiated by nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) sequence, geographic distribution, and basidiospore size. <i>Polyporus ponderosus</i> H. Schrenk is an earlier illegitimate synonym of <i>F. schrenkii</i>. Both <i>F. mounceae</i> and <i>F. schrenkii</i> have a heterothallic multiallelic incompatibility system.