Diversity of aphyllophoroid fungi from taxonomical and biogeographical perspectives

Comprehensive knowledge of biodiversity is a prerequisite for its long-term conservation and sustainable use. Fungi play crucial roles in ecosystems and are among the species-richest organism groups on Earth. However, all aspects of their diversity remain underexplored. In this study, we aimed to fill the gaps in occurrence data and taxonomy as well as in understanding spatial diversity patterns of aphyllophoroid fungi (non-gilled macroscopic Basidiomycota). We digitized and made openly accessible 4,041 records of aphyllophoroid fungi from Central and Eastern Europe and several tropical areas. Numerous specimen records were associated with newly generated nuclear ribosomal DNA sequences (74 of ITS regions and 59 of 28S region) and numerous observations also with photographs depicting diagnostic features of fungal fruitbodies. We described 13 new species of aphyllophoroid fungi based on morphological examination combined with DNA barcoding and phylogenetic Bayesian and Maximum likelihood analyses using ITS and 28S DNA sequences. Two new species belong to the genus Trechispora P. Karst. and eleven to the genus Subulicystidium Parmasto. In the latter, species-level variation in basidiospore size and shape was re-evaluated based on systematic measurements of 2,840 spores from 67 sequenced specimens. An updated identification key to all known species of Subulicystidium was provided. Using DNA-based evidence, in the studied lineage (Trechisporales K.H.Larss.) we showed for the first time a possibility of a transoceanic distribution. Based on a dataset consisting of 14,030 fruitbody occurrences of 1,491 aphyllophoroid fungal species from 39 European areas, we showed that importance of biogeographical regions in determining European aphyllophoroid fungal communities varies for different diversity components. Species richness and nestedness were best explained by European biogeographical regions, whereas overall beta-diversity and species turnover were driven mostly by variation in climate, and nestedness mostly by tree species occupancy. Beta diversity patterns of aphyllophoroid fungi did not differ between southern and northern Europe. Therefore, at the continental scale, aphyllophoroid fungi are less shaped by historical legacies than vascular plant and animal communities.