Epitypification of <i>Armillaria solidipes</i> , a cause of Armillaria root disease in North America

Although <i>Armillaria solidipes</i> was described in 1900, confusion has surrounded the appropriate use of this taxonomic epithet, largely because DNA sequence-based characterization and an associated culture were unavailable for the original holotype. An epitype for <i>A. solidipes</i> (previously known as North American Biological Species I) is established herein, along with morphological descriptions and genetic characterization that clearly distinguish <i>A. solidipes</i>, which is found in North America, from <i>A. ostoyae</i> (previously known as European Biological Species C), which is found in Eurasia. Of the five loci examined, translation elongation factor 1-alpha was the most useful for distinguishing <i>A. solidipes</i> from other <i>Armillaria</i> spp. including <i>A. ostoyae</i>. Further, the whole genome phylogeny of <i>A. solidipes</i> and <i>A. ostoyae</i> showed substantial differences that further demonstrate their separation. The specimen from Colorado, USA, which was collected in the locality where the original type specimen was collected, is designated as the epitype.