Three new species of <i>Alpova</i> from Japan: new insights into biogeography in <i>Alpova</i>

Alpova (Paxillaceae, Boletales) is an ectomycorrhizal fungal genus specifically colonizing alder trees. As observed in other hypogeous fungal taxa that depend on land animals for spore dispersal, Alpova shows strong biogeographical patterns. Although more than 10 Alpova species have been identified in Europe and North America, no Alpova species (except for three Chinese species possibly attributable to Melanogaster) has been formally described from East Asia, which has greater diversity of the host Alnus than other areas. Here, we describe three new Alpova species, i.e., A. fujisanensis sp. nov., A. japonicus sp. nov., and A. venosus sp. nov., collected under Japanese alder trees. Phylogenetic analysis using three DNA loci showed that these three Japanese Alpova species belong to distinctive clades and are distantly related to European and North American species. Both A. fujisanensis and A. japonicus were associated only with the host subgen. Alnobetula, while A. venosus was associated with the subgen. Alnus, indicating host specificity at the subgenus level.