Lichenoconium christiansenii sp. nov. is described and illustrated from the apothecia of Nodobryoria abbreviata (syn. Bryoria abbreviata) in Washington State, USA. The species recalls L. lichenicola, but differs in the more subglobose conidia and the shorter conidiogenous cells as well as in occurring on a different host. A key to the 14 species now known in the genus is provided. Lichenoconium cargillianum is also reported from Letharia vulpina for the first time.

Phoma fuliginosa sp. nov. is described and illustrated from apothecia of Caloplaca trachyphylla (Teloschistaceae) collected in Nebraska, USA. The species is distinguished from other lichenicolous fungi referred to the genus in the shape and size of the conidia. It is considered pragmatic to continue to use the generic name Phoma for this group of lichenicolous coelomycetes until cultural and molecular information is available, although these fungi may later prove not to be congeneric amongst themselves nor with the species occurring on plants. A key to the 14 lichenicolous species now accepted in Phoma is provided, and notes on reports of some additional collections referred to the genus are included.

Five Japanese species of the lichen genus Menegazzia are recorded. Menegazzia caviisidia Bjerke & P. James sp. nov. is characterized by numerous globose to dactyliform to narrowly obovate, hollow isidia, small conical perforations, and thamnolic acid as the major medullary constituent. It appears to be a rare species, so far known only from three localities on Honshu. The status of the primary species M. asahinae is elucidated. Menegazzia pedicellata Bjerke sp. nov. is a rare caperatic acid-containing species previously included in M. asahinae s. lat. Menegazzia asahinae s. str. has perforated margins of apothecia and contains the stictic acid complex. Menegazzia asahinae f. subimpertusa and M. pseudocyphellata are reduced to synonymy with M. asahinae s. str. Two sorediate species are known, viz. M. subsimilis and M. terebrata.

The phylogeny of the Micareaceae and the genus Micarea Fr. was studied using 39 nuclear small subunit ribosomal DNA sequences. Phylogenetic analyses were carried out using maximum parsimony, maximum likelihood, and Bayesian inference. A confidence set of trees was estimated using expected likelihood weights to investigate a series of hypotheses of monophyly. Tree topologies were very similar between methods and differed only in the placement of a few poorly supported branches. The results indicate that the Micareaceae in its current circumscription belongs in the Lecanorales, but that it is not monophyletic. Psilolechia, Micarea with a ‘non-micareoid’ photobiont, Micarea sensu stricto and Byssoloma form a paraphyletic grade in this study. Micarea sensu stricto and Byssoloma (Pilocarpaceae) form a strongly supported monophyletic group, which constitutes the sister group to the Bacidiaceae. Scoliciosporum A. Massal has sometimes been considered close to Micarea, but no support was found for that hypothesis.

The phylogenetic relationships of 16 species of Parmelia s. str. are presented based on sequences of nuITS rDNA from 56 specimens, and β-tubulin gene sequences from 29 collections. Parmelia serrana sp. nov. a Mediterranean species morphologically very close to P. saxatilis is described. Parmelia ernstiae is the sister-group to P. saxatilis s. str., and a further undescribed North American species of the P. saxatilis complex may require recognition. The isidiate P. squarrosa is closely allied to the sorediate P. sulcata, which is paraphyletic. Japanese samples of P. cochleata form a monophyletic group but too few collections of these were studied to reach firm conclusions regarding their relationships. An epitype is selected for the lectotype of Lichen saxatilis to unequivocally fix the application of that epithet.

The anatomy of the endolithic, calcicolous lichen Verrucaria rubrocincta Breuss is described using optical and scanning electron microscopy. This lichen is locally abundant in caliche plates of open desert pavements in the Sonoran Desert of south-western Arizona. The endolithic growth of V. rubrocincta is distinctly layered. The upper layer is a fine-grained calcite (micrite). This layer is sparsely penetrated by hyphae and therefore cannot be interpreted as a lithocortex sensu stricto. Beneath the micrite is the photobiont layer. Below this photobiont layer hyphae form a pseudomedulla penetrating up to 1 cm into the caliche. Calcium oxalates occur in the pseudomedulla but are absent from uninhabited caliche. The analogy of a greenhouse describes the ecophysiological adaptations of this endolithic growth to the environmental extremes of the Sonoran Desert. The micrite acts as a roof and the photobiont layer and pseudomedulla represent the greenhouse interior. Verrucaria rubrocincta has thus evolved a strategy to successfully establish and survive within an extreme environment. Our study illustrates biodeterioration and biomineralization processes acting simultaneously within a single lichen species. Mineralogical evidence suggests that the micrite on the thallus surface is biologically induced. The hyphae of the lichen biodeteriorate the caliche thus forming the pseudomedulla. Simultaneously with this process micrite forms at the surface protecting the thallus from exposure and counter-balancing rock degradation. These combined effects of biodeterioration and biomineralization do not markedly accelerate erosion because inhabited and uninhabited areas of the same plate show similar surface heights.

The aim of this investigation was to determine the NH4Cl concentration threshold, above which negative physiological effects would occur in the nitrophytic lichen Xanthoria parietina. Over a 10 month period, X. parietina thalli growing on roof tiles were exposed weekly to NH4Cl concentrations of 0·04, 0·17, 0·34 or 0·69 M. Nitrogen (N) uptake from ammonium and the concentrations of total thallus N and biont markers (chlorophyll a, ergosterol and chitin) were measured on four occasions, over the experimental period. Xanthoria parietina was able to assimilate a significant quantity of the applied ammonium. However, lichens exposed to the two higher concentrations suffered damage to both the photobiont and the mycobiont, as evidenced by reduced chlorophyll a and ergosterol concentrations, while lichens exposed to the two lower concentrations showed no significant changes in either chlorophyll a or ergosterol that could be related to the ammonium inputs. Xanthoria parietina tolerated a weekly irrigation of at least 0·17 M NH4Cl, corresponding to an N deposition of c. 1000 kg ha−1 yr−1, suggesting that this species has a very high tolerance to N pollution.