From one to five putative species: an unexpected high genetic diversity in Usnea flavocardia (lichenized Ascomycetes, Parmeliaceae) with the discovery of a new clade within the subgenus Usnea s.str.

In this study, we analyzed the genetic diversity within Usnea flavocardia, a widespread species found in all continents except Antarctica. The species is characterized by a shrubby thallus growth form, the presence of soralia, a yellow central axis and/or the presence of red dots on the cortex. Using ITS rDNA and two protein-coding genes (mcm7 and rpb1) in a multispecies coalescent (MSC) approach, we showed that U. flavocardia comprises five different lineages, four of which can be considered as putative new species. Each of the five lineages, except one, is characterized by specific chemical compounds. Within the outgroup that was used in this study, we furthermore showed that U. gaudichaudii and U. eulychniae, both endemic to Chile, constitute a new major clade in the subgenus Usnea s.str.