The species of Heterodermia in Brazil have been revised based on literature reports, public databases and examination of 500 recent specimens from 15 states. So far, 43 species have been reported in the literature, two of which are not accepted here. We report 10 additional species from Brazil and describe 15 new to science, mostly from the Atlantic rainforest biome, raising the total number to 68, including two still undescribed species from Santa Catarina State. A key to all accepted species is given, keying out more species than represented in any previously published key of the genus. Based on new phylogenetic work, we do not accept the split genera that were recently proposed. We do informally recognize an additional group, the H. dactyliza-group. The following species are described as new: Heterodermia amphilacinulata M. F. N. Martins & M. P. Marcelli, H. caneziae M. F. Souza & Aptroot, H. delicatula M. P. Marcelli & M. F. N. Martins, H. dissecticodiademata M. F. Souza & Aptroot, H. dissecticoflabellata M. F. Souza & Aptroot, H. flavodactyliza M. F. Souza & Aptroot, H. flavulifera M. F. Souza & Aptroot, H. labiata M. P. Marcelli & M. F. N. Martins, H. macrosoraliata M. P. Marcelli & M. F. N. Martins, H. minor M. F. Souza & Aptroot, H. neocrocea M. F. Souza & Aptroot, H. nigromarginata M. F. Souza & Aptroot, H. phyllalbicans M. F. Souza & Aptroot, H. spielmannii M. F. Souza & Aptroot and H. sublinearis M. P. Marcelli & M. F. N. Martins. The following new combinations are also proposed: Heterodermia africana (Kurok.) M. F. Souza & Aptroot and H. borphyllidiata (Kalb & Meesim) M. F. Souza & Aptroot. Dissectic acid was found in species belonging to three different groups and was not restricted to (and characteristic of) one subgroup, as previously reported.

Gene expression variation can be partitioned into different components (regulatory, genetic and acclimatory effects) but for lichen-forming fungi, the relative importance of each of these effects is unclear. Here, we studied gene expression in the lichen-forming fungus Lobaria pulmonaria in response to thermal stress and parasitism by the lichenicolous fungus Plectocarpon lichenum. Our experimental procedure was to acclimate lichen thalli to 4 °C over three weeks and then expose them to 15 °C and 25 °C for 2 hours each, sampling infected and visually asymptomatic thalli at each temperature. Quantitative Real-Time PCR was utilized to quantify gene expression of six candidate genes, normalizing expression values with two reference genes. We found that two genes encoding heat shock proteins (hsp88 and hsp98), two polyketide synthase genes (rPKS1, nrPKS3) and elongation factor 1-1-α (efa) were upregulated at higher temperatures. Moreover, we observed higher expression of hsp98 at 25 °C in samples infected by P. lichenum than in uninfected samples. Finally, in partial redundancy analyses, most of the explained variation in gene expression was related to temperature treatment; genetic variation and long-term acclimatization to sites contributed far less. Hence, regulatory effects (i.e. direct adjustments of gene expression in response to the temperature change) dominated over genetic and acclimatory effects in the gene expression variability of L. pulmonaria. This study suggests that L. pulmonaria could become a valuable lichen model for studying heat shock protein responses in vivo.

The genus Arthothelium A. Massal. in Tasmania comprises ten species. Five of these are described as new: A. bacidinum Kantvilas, a saxicolous, littoral species with subglobose apothecia, non-macrocephalic ascospores, 25−40 × 11−19 μm, and containing the pigment Endoaurantiacum-gold which yields a K+ red reaction; A. insolitum Kantvilas, lichenicolous in rainforest and characterized by subglobose apothecia, very large, non-macrocephalic ascospores, 50−80 × 22−40 μm, and containing the pigment Interveniens-brown which reacts K+ olive green; A. macounioides Kantvilas, corticolous in wet forest and characterized by sessile, convex apothecia, macrocephalic ascospores, 29−42 × 11−18 μm, and containing the pigment Endoaurantiacum-gold; A. magenteum Kantvilas, a common wet forest epiphyte with applanate apothecia, non-macrocephalic ascospores, 25−55 × 11−22 μm, and containing a unique maroon-red, K+ pink pigment; and A. subtectum Kantvilas, a saxicolous species with convex apothecia, macrocephalic ascospores, 22−36 × 9−14 μm, and containing Endoaurantiacum-gold. The New Zealand species A. endoaurantiacum Makhija & Patw. and A. suffusum (C. Knight) Müll. Arg., and the Australian A. velatium Müll. Arg. are recorded for Tasmania for the first time. The names A. obtusulum (Nyl.) Müll. Arg., A. pellucidum (C. Knight) Müll. Arg. and A. polycarpum Müll. Arg. are considered synonyms of the widespread A. ampliatum (C. Knight & Mitten) Müll. Arg. Arthothelium ferax Müll. Arg. is a synonym of A. interveniens (Nyl.) Zahlbr. and A. subspectabile Vĕzda & Kantvilas is a synonym of A. suffusum. The sole record of A. macrothecum (Fée) A. Massal. from Tasmania is found to be based on a misidentification. A key to the species is provided. The importance of apothecial pigments, apothecial morphology and ascospore septation is discussed, and three pigments are characterized by their appearance in water and other standard media.

Ramalina arsenii sp. nov. belongs to the R. pollinaria group and is easily recognized by its ITS barcode and several micro-morphological characters that are diagnostic in a European context: small size, less than 3 cm long; soralia developing on the underside of lobe apices; absence of excavate depressions on the lower side. Its ecological niche (i.e. rock outcrops and especially underhangs of slightly calcareous rocks, at low and mid altitudes) is also unique. Ramalina arsenii is frequent and locally abundant in France (Alps, Cantal) and Switzerland (western Alps), and is also known from Germany and the Spanish side of the Pyrenees.

To facilitate population-genetic studies, we developed simple sequence repeat (SSR) markers and a molecular species identification assay for Peltigera membranacea (Ascomycota, Peltigerales), a common ground-dwelling lichen of forest and tundra ecosystems. Additional markers were developed for its Nostoc photobiont. Twenty-one fungal markers for P. membranacea were found to be polymorphic, with the number of alleles ranging from 3–21. Nei's unbiased gene diversity ranged from 0.588 to 0.640 in four significantly structured (FST = 0.059) mycobiont populations. For the Nostoc photobiont, 14 polymorphic SSR were developed, yielding 4–14 alleles each, with gene diversity ranging from 0.062 to 0.771 in four populations showing substantial population structure (FST = 0.278). The new markers developed are suitable for population genetic studies of Peltigera membranacea and of its cyanobiont, and at the same time allowed us to distinguish 98.5% of P. membranacea specimens from morphologically similar species of Peltigera.

Inland dune ecosystems are rich in terricolous lichen species. However, these communities are sensitive to human activities, both locally and globally. Since terricolous lichens have a dominant role in semi-arid sandy grasslands, it is important to explore the composition of their communities and the environmental factors affecting them. We studied the structure of the terricolous lichen assemblages of calcareous grassland in an inland duneland ecosystem by comparing the lichen communities of arid and humid dune sides on two sites with different disturbance histories. Microcoenological data were collected according to the Braun-Blanquet method. Environmental variables include the cover of bare soil, moss, litter, herb cover and height of herbs. We investigated the relationship of these variables and the presence and absence data of terricolous lichen species to sites and dune side. We found that the site had a significant effect on species richness that might reflect the different types and severity of previous disturbance events at the studied sites. On a smaller, ‘dune’ scale, in general lower herb cover and height and a higher moss cover were characteristic of arid dune sides. Most of the frequent species were negatively affected by higher moss cover. Some lichen species were more abundant (e.g. Cladonia furcata) or found only (e.g. Xanthoparmelia subdiffluens, Gyalolechia fulgens) on arid dune sides, while others preferred (e.g. C. pyxidata) or occurred only on (e.g. Peltigera species, C. rei) humid sides. It was observed that the impact of the dune side on several variables differed between sites. The diverse microhabitat types, microclimate and landscape structure, results in species-rich and valuable terricolous lichen communities forming in inland dune ecosystems.

To clarify deep relationships among species lineages within Bacidia s. str., and to investigate the robustness of the deeper branches, we combined data from three traditionally used RNA-coding genes (nrITS, nrLSU and mtSSU) with two protein-coding genes (RPB1 and RPB2). The multigene phylogeny contained 48 newly generated sequences from the Russian Far East and all Bacidia s. str. sequences from GenBank (131 sequences). We subjected the alignments for the single and concatenated data sets to Bayesian inference (BI) and two maximum likelihood (ML) analyses (RAxML and IQ-TREE). The topologies of phylogenetic trees recovered from BI and ML analyses were highly concordant. The multilocus phylogeny of Bacidia s. str. was congruent with previous results based on nrITS sequences from the Russian Far East but with considerably higher support values for most of the deeper branches. A correlation between the recovered clades and apothecial pigments in the upper part of the hymenium and lateral exciple was observed. Based on morphological and molecular evidence, Bacidia obtecta is described as new to science. It was recovered as the sister lineage of B. elongata. The two species are alike in having up to four enlarged lumina cells along the exciple edge, but B. obtecta differs in the abundant crystals found in the upper hymenium and lateral exciple, and by having spores with fewer septa.

The new genus Australidea Kantvilas, Wedin & M. Svensson is described to accommodate Lecidea canorufescens Kremp., a widespread lichen in temperate Australasia. It is characterized by a crustose thallus with a green photobiont, reddish brown, biatorine apothecia with an internally hyaline, cupulate proper exciple constructed of branched and anastomosing hyphae, mainly simple paraphyses, 8-spored, Porpidia-type asci and simple, hyaline, non-halonate ascospores. A phylogenetic analysis places the new genus in the family Malmideaceae. Lecidea canorufescens Kremp., L. glandulosa C. Knight, L. immarginata R. Br. ex Cromb. and L. intervertens Nyl. are lectotypified. These names, plus L. dacrydii Müll. Arg. and L. eucheila Zahlbr., are all synonyms of Australidea canorufescens (Kremp.) Kantvilas, Wedin & M. Svensson comb. nov. Several genera superficially similar to Australidea, including Malcolmiella Vĕzda, Malmidea Kalb et al. and Myochroidea Printzen et al., are compared. A comprehensive anatomical and morphological description of the genus Malcolmiella, recorded for Tasmania for the first time, is also provided. The new combination M. interversa (Nyl.) Kantvilas, Wedin & M. Svensson is introduced and the names M. cinereovirens Vĕzda and M. cinereovirens var. isidiata Vĕzda are reduced to synonyms. The systematic position of this genus remains unclear, although phylogenetic analysis suggests its affinities lie with a group of genera that includes Bryobilimbia Fryday et al., Romjularia Timdal and Clauzadea Hafellner & Bellem.

A review of algal (including cyanobacterial) symbionts associated with lichen-forming fungi is presented. General aspects of their biology relevant to lichen symbioses are summarized. The genera of algae currently believed to include lichen symbionts are outlined; approximately 50 can be recognized at present. References reporting algal taxa in lichen symbiosis are tabulated, with emphasis on those published since the 1988 review by Tschermak-Woess, and particularly those providing molecular evidence for their identifications. This review is dedicated in honour of Austrian phycologist Elisabeth Tschermak-Woess (1917–2001), for her numerous and significant contributions to our knowledge of lichen algae (some published under the names Elisabeth Tschermak and Liesl Tschermak).

Non-photochemical quenching (NPQ) plays an important role in protecting photosynthetic organisms from photoinhibition by dissipating excess light energy as heat. However, excess NPQ can greatly reduce the quantum yield of photosynthesis at lower light levels. Recently, there has been considerable interest in understanding how plants balance NPQ to ensure optimal productivity in environments in which light levels are rapidly changing. In the present study, chlorophyll fluorescence was used to study the induction and relaxation of non-photochemical quenching (NPQ) in the dark and the induction of photosynthesis in ten species of lichens, five sampled from exposed and five sampled from shaded habitats. Here we show that the main difference between sun and shade lichens is the rate at which NPQ relaxes in the dark, rather than the speed that photosynthesis starts upon illumination. During the first two minutes in the dark, NPQ values in the five sun species declined only by an average of 2%, while by contrast, in shade species the average decline was 40%. For lichens growing in microhabitats where light levels are rapidly changing, rapid relaxation of NPQ may enable their photobionts to use the available light most efficiently.

Gibbosporina cyanea is described here as new to science, based on its holotype collected in Sri Lanka in the 1860s. The species is a bipartite cyanolichen in contrast to all other known Gibbosporina species, which are tripartites. The species appears to have evolved through cephalodia emancipation followed by divergence. Phyllidia indicate a cephalodiate evolutionary origin with a continued function similar to vegetative propagules. The species is considered to represent a relatively young speciation within an evolutionary old genus and G. sphaerospora is discussed as a possible candidate for being its closest known relative based on spore morphology. As the species appears to be so different from the remaining Gibbosporina species, it is compared here to representatives of other related palaeotropical cyanogenera, such as Leightoniella, Lepidocollema, Pannaria and Physma. Perispore structure is shown to be a useful character in separating these genera, including distinct clades of the non-monophyletic genera Physma and Lepidocollema. Leightoniella zeylanensis is reported here as new to Japan, and it is concluded that Pannaria lurida needs to be restudied in India and Sri Lanka.

Caloplaca tephromelae Kantvilas, Suija & Motiej., a lichenicolous species growing on saxicolous thalli of species of Tephromela, is described from Tasmania. The new species is characterized by lecanorine to zeorine apothecia with a whitish grey thalline margin devoid of anthraquinone pigments, a non-inspersed hymenium, paraphyses without oil vacuoles and ascospores 10–14 × 5–8 μm, with a septum 5–8 μm thick. It is compared with selected taxa of Caloplaca s. lat. that share these salient features. Molecular data support the distinctiveness of the new species but do not suggest any obvious close relatives.