Lichenomphalia umbellifera: fungible and infungible epithets and species concepts

Comparison of the protologue of Agaricus umbellifer L. with specimens and descriptions of the basidiolichen Lichenomphalia umbellifera (L.) Redhead & al. revealed that the epithet umbellifera was misapplied to the Lichenomphalia species, causing several major conflicts with Linnaeus’s species concept. A felicitous match for Linnaeus’s species concept was found with a species of Marasmius sect. Epiphylli. Because A. umbellifer falls in a group that arises from an evolutionary pathway divergent from that leading to Marasmius s. str., we erected a new genus, Owingsia, to accommodate it, and recombined the type species as Owingsia umbellifera. Molecular studies demonstrated that it is a widely distributed circumpolar species, prevalent in Lapland and islands of the Baltic Sea, where Linnaeus encountered it. The earliest legitimate description of the basidiolichen L. umbellifera is A. pseudoandrosaceus Bull., a name superseded by the sanctioned later synonym, A. ericetorum Pers. We recombined this basionym as L. ericetorum, and epitypified O. umbellifera and L. ericetorum with modern sequenced specimens.