Multigene phylogeny and taxonomic revision of Atheliales s.l.: Reinstatement of three families and one new family, Lobuliciaceae fam. nov.

Atheliales (Agaricomycetes, Basidiomycota) is an order mostly composed of corticioid fungi, containing roughly 100 described species in 20 genera. Members exhibit remarkable ecological diversity, including saprotrophs, ectomycorrhizal symbionts, facultative parasites of plants or lichens, and symbionts of termites. Ectomycorrhizal members are well known because they often form a major part of boreal and temperate fungal communities. However, Atheliales is generally understudied, and molecular data are scarce. Furthermore, the order is riddled with many taxonomic problems; some genera are nonmonophyletic and several species have been shown to be more closely related to other orders. We investigated the phylogenetic position of genera that are currently listed in Atheliales sensu lato by employing an Agaricomycetes-wide dataset with emphasis on Atheliales including the type species of genera therein. A phylogenetic analysis based on 5.8S, LSU, rpb2, and tef1 (excluding third codon) retrieved Atheliales in subclass Agaricomycetidae, as sister to Lepidostromatales. In addition, a number of Atheliales genera were retrieved in other orders with strong support: Byssoporia in Russulales, Digitatispora in Agaricales, Hypochnella in Polyporales, Lyoathelia in Hymenochaetales, and Pteridomyces in Trechisporales. Based on this result, we assembled another dataset focusing on the clade with Atheliales sensu stricto and representatives from Lepidostromatales and Boletales as outgroups, based on ITS (ITS1-5.8S-ITS2), LSU, rpb2, and tef1. The reconstructed phylogeny of Atheliales returned five distinct lineages, which we propose here as families. Lobulicium, a monotypic genus with a distinct morphology of seven lobed basidiospores, was placed as sister to the rest of Atheliales. A new family is proposed to accommodate this genus, Lobuliciaceae fam. nov. The remaining four lineages can be named following the family-level classification by Julich (1982), and thus we opted to use the names Atheliaceae, Byssocorticiaceae, Pilodermataceae, and Tylosporaceae, albeit with amended circumscriptions. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of British Mycological Society.

Automated summary

Atheliales is an order of corticioid fungi with diverse ecological roles, yet understudied and plagued with taxonomic problems. A phylogenetic analysis identified five distinct lineages within Atheliales, proposed as families by the researchers.