Ascus types are phylogenetically misleading in Trapeliaceae and Agyriaceae (Ostropomycetidae, Ascomycota).

The phylogeny of Agyriaceae was investigated using MP and Bayesian approaches based on a combined dataset of nuLSU rDNA, mtSSU rDNA, and RPB1 sequences of 78 ascomycetes. The type genus of the family is shown to be a strongly supported sister to Coccotremataceae+Pertusariaceae, whereas the remaining species currently classified in Agyriaceae have a well-supported sister-group relationship with Baeomycetales. Monophyly of Agyriaceae is significantly rejected using two independent alternative topology tests. The micromorphology in Agyriaceae s. lat., Coccotremataceae, and Pertusariaceae is restudied. It is confirmed that the ascus type of Agyrium agrees with that of other taxa currently placed in Agyriaceae, and hence the ascus type is interpreted as homoplasious and phylogenetically misleading in this group of fungi. Consequently, we suggest that Trapeliaceae be resurrected for the lichenized taxa currently classified in Agyriaceae, and that this family be placed in Baeomycetales. The ordinal classification in Ostropomycetidae, especially the circumscription of Pertusariales and its distinction from Agyriales, requires additional studies.