Revision: Lichenomphalia umbellifera: fungible and infungible epithets and species concepts

Abstract

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 grossly misapplied to the basidiolichen, causing several major conflicts with Linnaeus’s species concept. In the region where Linnaeus collected A. umbellifer we discovered a species of Marasmius sect. Epiphylli, congruent with Linnaeus’s protologue. Because M. sect. Epiphylli arises from an evolutionary pathway divergent from that leading to Marasmius s. str., we erected a new genus, Owingsia, to accommodate it, and recombined A. umbellifer as O. umbellifera, type species of the genus, naming our collection epitype for this species. Molecular studies cemented the concinnity of A. umbellifer with our collection: O. umbellifera is the most common of several similar species in a complex prevalent in Lapland, where Linnaeus first encountered it, and in the complex, O. umbellifera shares the pileal shape of its lectotype and most closely resembles it regarding stipe length, is widely distributed beyond the regions where Linnaeus found it, encompassing the regions of its lecto‐ and epitype, and sharing substrates with both. The earliest legitimate description of the basidiolichen previously known as L. umbellifera is A. pseudoandrosaceus Bull., a name superseded by the sanctioned later synonym, A. ericetorum Pers.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 it with a modern sequenced specimen.