Global phylogeny and taxonomic reassessment of the lichen genus Dendriscosticta (Ascomycota: Peltigerales)

The genus Dendriscosticta (Ascomycota: Peltigerales) encompasses several distinctive lichen-forming fungal species restricted to the Northern Hemisphere. Most are flagship species of old-growth forests with good air quality. A global phylogeny of the genus based on multilocus sequence data (ITS, RPB1, EF-1 alpha, MCM7), model-based phylogenetic methods, and morphological and chemical assessments, reveals a high level of cryptic speciation often associated with restricted geographical distribution and/or chemical characters. Using sequence-based species delimitation approaches, we circumscribe two main clades referred to as the D. wrightii clade, with five unequivocal species, including D. gelida sp. nov., and the D. praetextata clade, with eight putative species, including D. phyllidiata sp. nov. The absence of recently collected material of D. hookeri comb. nov. from the type locality unfortunately prevents assignment of this epithet to one of the five supported lineages sharing this morphotype. Three new combinations are proposed: D. hookeri, D. insinuans comb. nov. and D. yatabeana comb. nov. Epitypes are designated for D. wrightii and D. yatabeana. Species diversity within the genus increased from four to nine. Our morphological assessment confirmed that Sticta and Dendriscosticta can be readily distinguished by the presence of excipular algae whereas the structure of the lower surface pores is not a reliable diagnostic feature.

Automated summary

The genus Dendriscosticta includes several unique lichen-forming fungal species primarily found in old-growth forests in the Northern Hemisphere. A global phylogeny of the genus revealed a high level of cryptic speciation with two main clades identified, the D. wrightii clade with five species and the D. praetextata clade with eight potential species. The study also proposed three new combinations and increased the species diversity within the genus from four to nine.