Towards an integrative taxonomy of Phyllopsora (Ramalinaceae)

Species identification in the tropical lichen genus Phyllopsora is generally challenging and is based on ascospore morphology, vegetative dispersal units, thallus structure and secondary chemistry. As several type specimens are in poor condition and difficult to interpret, it is often unclear how these old names fit with the currently used taxonomy. In the present study, we aim to identify species boundaries in Phyllopsora s. str. supported by an integrative approach using multiple sources of evidence. We investigated a substantial amount of herbarium as well as freshly collected material and generated mtSSU and ITS sequence data from most of the described species, including several types. Species delimitation analyses are applied on the gene trees using mPTP and we construct a species tree of both markers with *BEAST, facilitating discussion of species delimitation and sister-relationships. Comparing morphology, chemistry and molecular data, we found that the mPTP analyses split established species repeatedly. Based on our integrative results, we exclude nine species from the genus, resurrect one (P. melanoglauca Zahlbr.), reduce two into synonymy with other Phyllopsora species and describe five as new to science: Phyllopsora amazonica Kistenich & Timdal (which shares the secondary chemistry (atranorin and terpenoid pattern) with P. halei chemotype 1, but differs, e.g., in having smaller areolae that are attached to a thinner, white prothallus, and in having more persistently marginate and less convex apothecia), Phyllopsora concinna Kistenich & Timdal (which shares the secondary chemistry (atranorin and parvifoliellin) with P. parvifoliella and P. rappiana, but differs from both in forming larger isidia, having a white prothallus, apothecial margin paler than the disc, and longer and broader ascospores), Phyllopsora furfurella Kistenich & Timdal (which is here segregated from P. furfuracea based on having a white prothallus and in containing skyrin in the hypothecium (K+ red)), Phyllopsora isidosa Kistenich & Timdal (which differs from P. byssiseda in forming a more crustose thallus with more delicate isidia, and from P. isidiotyla in forming somewhat coarser, less branched isidia) and Phyllopsora neotinica Kistenich & Timdal (a neotropical species here segregated from the now exclusively paleotropical P. chodatinica, differing in containing an unknown xanthone (not chodatin)). Lectotypes are designated for Biatora pyrrhomelaena Tuck., Lecidea leucophyllina Nyl., L. pertexta Nyl., and P. brachyspora Mull. Arg. In total, we accept 54 species in the genus Phyllopsora.