A revised circumscription of Marthamycetales based on a complete sampling of the types of genera, Propoliaceae, fam. nov., and placement of in Leotiomycetes.

Marthamycetales species are widely distributed, non-lichenized, apothecial ascomycetes that are associated with various woody plants and grasses. Most species are presumed to be saprobes, although a few are pathogens. Apothecia are small and erumpent, with farinose discs that are encircled by ragged, projecting flaps of degraded plant tissue. Marthamycetales is placed in Leotiomycetes and currently circumscribes nine genera: , and . However, because representative species of four genera have not been sampled in previous phylogenetic studies, the circumscription of the order and evolutionary relationships of taxa within it have remained unclear. In this contribution, we obtained a complete sampling of the types of all nine genera. We assembled a four-locus data set and performed maximum likelihood and Bayesian phylogenetic analyses. Our results are congruent with previous analyses: Marthamycetales is phylogenetically isolated within Leotiomycetes and is composed of two distinct, well-supported clades. One clade includes primarily filiform-spored, leaf-inhabiting species in Marthamycetaceae sensu stricto, whereas the second clade includes primarily cylindrical/elliptical-spored, woody tissue-inhabiting species. We name this latter clade Propoliaceae, fam. nov. Sequences of , type of the genus, group within this Propoliaceae clade. is excluded from Marthamycetales and placed in Arachnopezizaceae, Helotiales. is synonymized under , and the new combination is proposed. Lectotypes are designated for and . A revised and expanded description of Marthamycetales is provided, along with diagnoses for Marthamycetaceae and Propoliaceae. is placed in Leotiomycetes based on the first published sequences of this species. However, its ordinal-level phylogenetic relationships remain unknown. Our results provide a taxonomic framework for future studies in the diversity and ecology of Marthamycetales and a starting point for future work on the phylogenetic classification and global diversity of the genus .