Phylogenetic relationships among false truffle genera of Paxillaceae- Alpova, Melanogaster, Neoalpova, and Paralpova, gen. nov

A phylogenetic analysis of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), nuc rDNA 28S domains D1-D2 (28S), and the region between conserved domains 6 and 7 of RNA polymerase II second largest subunit (RPB2) from multiple species of Alpova and Melanogaster revealed four major clades, proposed here as distinct genera: Melanogaster, Alpova s. str. containing the type species A. cinnamomeus, Neoalpova for the species around N. rubescens, and the new genus Paralpova, proposed here for P. artikutzensis, sp. nov. Alpova, Neoalpova, and Paralpova form a monophyletic lineage of hypogeous fungi with a pseudoparenchymatic structure in their peridium (at least in the inner layer) that could be interpreted as a single genus, but they are separated due to distinct morphological and ecological traits. Alpova s. str. is employed for species strictly associated with Alnus, lacking a conspicuous odor, and producing relatively small basidiomata and basidiospores <10 µm long. Neoalpova and Paralpova occur under other hosts, present a conspicuous odor, have larger basidiomata and basidiospores than Alpova, and have a prosenchymatic peridiopellis. Finally, Paralpova is characterized by the yellowish gleba, monosporic or bisporic basidia, and basidiospores >15 µm long with a mean length/width ratio (Q_m) of <2.0. In addition, two new species of Neoalpova are proposed: N. arenicola, associated with Mediterranean forests in sandy soils and with spores slightly smaller and wider than those of N. rubescens, and N. montecchii, a cryptic species very similar to N. rubescens but for its putatively smaller peridiopellis elements and its genetic profile.