Phylogenetic study documents different speciation mechanisms within the Russula globispora lineage in boreal and arctic environments of the Northern Hemisphere

The <i>Russula globispora</i> lineage is a morphologically and phylogenetically well-defined group of ectomycorrhizal fungi occurring in various climatic areas. In this study we performed a multi-locus phylogenetic study based on collections from boreal, alpine and arctic habitats of Europe and Western North America, subalpine collections from the southeast Himalayas and collections from subtropical coniferous forests of Pakistan. European and North American collections are nearly identical and probably represent a single species named <i>R. dryadicola</i> distributed from the Alps to the Rocky Mountains. Collections from the southeast Himalayas belong to two distinct species: <i>R. abbottabadensis</i> sp. nov. from subtropical monodominant forests of <i>Pinus roxburghii</i> and <i>R. tengii</i> sp. nov. from subalpine mixed forests of <i>Abies</i> and <i>Betula</i>. The results suggest that speciation in this group is driven by a climate disjunction and adaptation rather than a host switch and geographical distance.