There is still a high diversity of lichen-forming fungi that remains undescribed, especially cryptic lineages at the species level. Integrating morphological, chemical, and DNA sequence data has proved useful in corroborating species descriptions and delimitations. Here we reviewed morphological features, secondary metabolites and the DNA sequences of ITS, mtSSU and nuLSU markers to study the diversity of Xanthoparmelia in southern Africa. A total of 37 species were recorded. Three of these appear undescribed, and we therefore describe them here as new: Xanthoparmelia nimisii, with a sorediate thallus and broad lobes, is well supported as a clade separate from X. annexa; X. pseudochalybaeizans with a white medulla is phylogenetically distinct from the otherwise similar X. chalybaeizans; and X. sipmaniana, well supported as a separate clade from the similar X. hypoprocetrarica. In addition, the separation of Xanthoparmelia capensis and X. tinctina requires further studies.

Based on findings in vascular plants showing that the capacity to provide enough carbon skeletons for rapid ammonium assimilation into amino acids is a prerequisite for tolerance to eutrophication, we tested the hypothesis that lichens from shady habitats are particularly sensitive to nitrogen pollution. We tested this hypothesis using published ecological indicator values (estimates of eutrophication tolerance and light preferences on an ordinal scale) for more than 500 central European lichen species. Our results show that shade-adapted lichens are indeed at the same time intolerant to eutrophication. However, not all eutrophication-sensitive lichens inhabit shady environments, suggesting the existence of several independent mechanisms causing intolerance of high nitrogen levels in lichens. The correlation of shade adaptation with nitrogen intolerance is limited to epiphytic and saxicolous species, since terricolous lichens are out-competed by vascular plants in dense vegetation. Our results suggest that lichen communities of shady bark, wood and rock are particularly sensitive to eutrophication.

Buellia peregrina is described as new to science from small limestone pebbles on exposed ground of the coastal Namib Desert, Namibia. The species is unusual for two reasons: (1) it is the only species in Buellia s.l. currently known to grow euendolithically, i.e., establishing a thallus entirely within its rock substratum, and (2) its apothecia contain a previously unknown blue pigment, here described as peregrina-blue according to its colour and characteristic reactions with HNO3, KOH and HCl.

The new species Arthothelium desertorum is described from the Namib desert. It is characterized by its saxicolous habit and areolate thallus containing divaricatic acid.