The species complex of Tephromela atra is one example of a widely distributed and highly polymorphic species, adapted to multiple substrates and ecological niches, whose diversity was recently investigated worldwide. Here, we provide improved morphological and molecular analyses to understand the diversity of corticolous taxa and support the recognition of a new species. We included specimens from the Mediterranean region and from the Pacific Northwest coast of North America and analysed the genetic diversity of both mycobionts and photobionts. Our study
confirms the presence of a new monophyletic lineage, here described as Tephromela pacifica, which is further characterized by the production of a new, still unnamed, lichen secondary compound. The corticolous Tephromela samples from the Mediterranean region are consistently recovered in two paraphyletic lineages and their diversity is herewith discussed.
