Species Diversification of the Coniferous Pathogenic Fungal Genus (Hymenochaetales, Basidiomycota) in Association with Its Biogeography and Host Plants.

, belonging to Hymenochaetaceae and now segregated from , is a wood-inhabiting fungal genus with three species, each having a specific geographic distribution and a strong host specificity as a forest pathogen of coniferous trees. In this study, the species diversity of is further clarified with the aid of a wider sampling and multilocus-based phylogenetic analysis, which reveals a new species . The molecular clock and ancestral geographic origin analyses indicate that the ancestor of emerged in one of the Pinaceae and Cupressaceae, then jumped to the other plant family originated in eastern Eurasia 17.01 million years ago (Mya; 95% highest posterior density: 9.46 to 25.86 Mya), and later extended its distribution to western North America, Central Asia, and eastern Europe. speciated on Pinaceae in eastern Eurasia 8.78 Mya (9.46 to 25.86 Mya) and then extended its distribution to western North America and eastern Europe. and speciated on in eastern Eurasia 3.67 Mya (0.36 to 8.02 Mya) and on in Central Asia 4.35 Mya (0.94 to 8.37 Mya), respectively. The speciation event of occurred 4.45 Mya (0.77 to 9.33 Mya) right after the emergence of its host, the endemic Cupressaceae species , and soon after, this fungus evolved to also inhabit another endemic Cupressaceae species . In summary, this study for the first time unambiguously clarified and timed the adaptive evolutionary event of in association with its biogeography and host plants.