Hidden diversity and chemical variation within Parmelia saxatilis group (Lecanorales, lichenized Ascomycota) and description of a new species P. tobolewskiana.

The Parmelia saxatilis group comprises four species in Europe with true isidia that share similar morphology, chemistry, and ecology. These include the widely distributed P. ernstiae, P. saxatilis, and P. serrana, and the potentially endemic species P. rojoi (excluded from the study). They are often referred to as semi-cryptic species, which significantly hinders their proper identification. The present study objectives were (1) to confirm the presence of galbinic acid in Parmelia taxa using the RP-HPLC method; (2) to verify if galbinic acid samples form a clade within the phylogenetic tree; and (3) to provide the first comprehensive chemical profiles of secondary metabolites present in isidiate Parmelia species. The study based on ca. 600 specimens focused on the chemical variability of these three species, paying particular attention to the presence of galbinic acid, rarely reported from this group of lichens. We detected galbinic acid in all studied species, mostly in P. saxatilis, then in P. ernstiae and for the first time in P. serrana. Fourteen chemotypes were identified in the studied samples, including eight detected for the first time. Nine chemotypes have been identified in P. ernstiae. Parmelia saxatilis shows seven chemotypes, often with galbinic acid and always without fatty acids. Parmelia serrana shows eight chemotypes. Phylogenetic relationships between specimens containing galbinic acid revealed that they do not cluster together. Based on the study new species P. tobolewskiana is proposed.