THE RESPONSE OF DIFFERENTCLADONIASPECIES AFTER TREATMENT WITH FERTILIZER OF LIME IN HEATHLAND

The effect of deposition of different fertilizers and of lime on lichens was investigated under field conditions. Three terricolous lichens were tested:Cladonia floerkeanaC. furcataandC. portentosa. The lichens were exposed to three types of powdered fertilizer (NPK-, N-, P-fertilizer) and lime. The applied nutrients were recorded in lichen thalli and soil. the influence on lichen growth rate and vegetation cover was estimated over 2 years. The response was a clear change in vegetation cover with an exceptional stimulating effect of NPK on the mossPolytrichum formosum. A lethal effect was observed onCladonia floerkeanafollowing exposure to lime. NPK and P had the most significant stimulatory effect onC. furcata. Only NPK promoted the growth ofC. portentosaand P, N or Ca had a negative effect.     

Yeast population of the Kindo Peninsula lichens

Yeast abundance and species diversity in the lichens collected at the Kindo Peninsula (Karelia) were studied. A total of 14 lichen species analyzed belonged to the genera Bryoria, Cladonia, Hypogymnia, Icmadophila, Nephroma, Peltigera, and Ramalina. Abundance of cultured yeasts in lichens was intermediate between soil and phyllosphere. The average yeast number on lichens was ~2.5 × 10³ CFU/g, while it exceeded 8 × 10³ CFU/g on plants and reached only 1 × 10³ CFU/g in soil. Yeast population of different parts of Cladonia lichens was found to vary significantly in abundance, species diversity, and community structure. The highest yeast abundance and diversity were revealed in the growth zone. Fifteen yeast species were isolated from lichens, including 6 basidiomycetous and 9 ascomycetous ones. Unlike soils and plants, yeast population of lichens consisted mainly of ascomycetous species, with predominance of Candida sphagnicola and anamorphous yeasts of the genus Dothiora. These results show that yeasts from different taxonomic and ecological groups are a necessary component of lichens; conditions favoring the preservation and development of specific yeast communities differing from the typical soil and phyllosphere yeast complexes are formed in the lichens of northern taiga forests.     

Removal of secondary compounds increases invertebrate abundance in lichens

We investigated how lichen carbon-based secondary compounds (CBSCs) affect abundance of invertebrates in five lichen species growing on the forest floor (Cladonia rangiferina, Cladonia stellaris) or on tree trunks (Evernia prunastri, Hypogymnia physodes, Pseudevernia furfuracea). To do this, CBSCs were removed by rinsing lichen thalli in acetone (which has no adverse effects on the lichens) and the lichens were re-transplanted in their natural habitat. After 4 months there was higher abundance of mites, springtails and spiders in the three epiphytic lichens that had their CBSC concentrations reduced. The increase in predatory spiders following CBSC reduction suggests that the compounds have multitrophic consequences. The acetone treatment reduced the number of nematodes in four of the lichen species. Given that lichens serve as important habitats for a diverse range of invertebrates, increased knowledge of how lichen CBSCs may regulate their abundance helps us to better understand the role that lichens and their defence compounds play in structuring forest food webs.     

A Three-Scale Analysis of Bacterial Communities Involved in Rocks Colonization and Soil Formation in High Mountain Environments

Alpha and beta diversities of the bacterial communities growing on rock surfaces, proto-soils, riparian sediments, lichen thalli, and water springs biofilms in a glacier foreland were studied. We used three molecular based techniques to allow a deeper investigation at different taxonomic resolutions: denaturing gradient gel electrophoresis, length heterogeneity-PCR, and automated ribosomal intergenic spacer analysis. Bacterial communities were mainly composed of Acidobacteria, Proteobacteria, and Cyanobacteria with distinct variations among sites. Proteobacteria were more represented in sediments, biofilms, and lichens; Acidobacteria were mostly found in proto-soils; and Cyanobacteria on rocks. Firmicutes and Bacteroidetes were mainly found in biofilms. UniFrac P values confirmed a significant difference among different matrices. Significant differences (P < 0.001) in beta diversity were observed among the different matrices at the genus–species level, except for lichens and rocks which shared a more similar community structure, while at deep taxonomic resolution two distinct bacterial communities between lichens and rocks were found.     

Comparative ecophysiology of three Placopsis species, pioneer lichens in recently exposed Chilean glacial forelands

Lichen species belonging to the genus Placopsis are early colonisers on snow free moraines of exposed land surfaces in the subantarctic region of Tierra de Fuego, South Chile. The physiological performance of three co-occurring species, P. pycnotheca, (terricolous), and P. perrugosa, and P. stenophylla (both saxicolous) was studied. All, possess green algal photobionts but have cyanobacteria in cephalodia. It was found that there was (i) a strong positive correlation between the acetylene reduction rate (AR) and the maximum photosynthetic rate (Amax), between the N content and the AR rate, and between the N and P contents, and (ii) the relationship between the CO₂-exchange rates and the responses obtained in the laboratory reflected the ecology of these three lichens in the field. The results provide new information about the dynamics of some of the fastest growing crustose lichens. We hypothesize that the performance of these three species may have developed as a response to growing in an unstable environment that resulted from frequent glacial fluctuations.     

Assessment of biological colonization of historic buildings in the former Auschwitz II-Birkenau concentration camp

The objective of this study was to assess biological colonization of wooden and brick buildings in the former Auschwitz II-Birkenau concentration camp, and to identify the organisms colonizing the examined buildings. Microbiological analysis did not reveal increased microbial activity, and the total microbial count of the barrack surfaces did not exceed 10³ CFU/100 cm². However, certain symptoms of biodegradation of the buildings were observed. The predominant microflora consisted of bacteria of the genera Bacillus, Sporosarcina, Pseudomonas, Micrococcus, Streptomyces, and Staphylococcus, as well as fungi of the genera Acremonium, Cladosporium, Alternaria, Humicola, Penicillium, and Chaetomium. The microflora patterns varied both in wooden and brick buildings. The structural elements of wooden and brick barracks, and especially of the floors and lower parts of bathroom walls, were infected by cyanobacteria and algae, with the most numerous being cyanobacteria of the genera Scytonema, Chroococcus, Gloeothece, Leptolyngbya, diatoms of the genus Diadesmis, and chlorophytes of the genera Chlorella and Apatococcus. The outer surfaces of the examined buildings were primarily colonized by lichens and bryophytes, with nearly 30 species identified. The dominant species of lichens belonged to the genera Candelariella, Caloplaca, Lecanora, Lecidea, Lepraria, Physcia, and Protoparmeliopsis, and those of bryophytes to the genera Bryum, Ceratodon, Marchantia, and Tortula. The quantity and species diversity of lichens and mosses were much lower in wooden barracks than in brick ones. The external surfaces of those barracks were only affected by Lecanora conizaeoides, Lecanora symmicta, Lepraria cf. incana, and Strangospora pinicola. The study results revealed vast biodiversity among the species colonizing historic buildings. The presence of these groups of organisms, resulting from their natural expansion in the environment, is undesirable, as their excessive growth and spread may lead to progressive biodegradation of buildings. Our assessment of biological contamination will enable the development of a disinfection and conservation plan for the examined buildings.     

The lichen cushion: A functional perspective of color and size of a dominant growth form on glacier forelands

Mat-forming lichens dominating high-latitudinal habitats vary in color and geometry. Widespread species are light greenish yellow (usnic acid) and reflect solar radiation, whereas melanic species absorbing most solar wavelengths are spatially more restricted. Color thereby influences lichens’ energy budget and thus their hydration and photosynthetically active periods. By using well-defined cushions from early successional stages on glacier forelands – three melanic^(m) and three usnic^(u) mat-forming lichens with hair-like branches (Alectoria ochroleuca^(u), Gowardia nigricans^(m)), hollow terete branches (Cladonia uncialis^(u), Cetraria muricata^(m)), and flat branches (Flavocetraria nivalis^(u), Cetraria islandica^(m)) – we quantified hydration traits and analyzed how color and cushion size affect water loss rate (WLR) and duration of active periods. Main findings: 1) WLR declined with cushion size and was highest in melanic lichens. 2) Active periods were longer for usnic than for melanic lichens and increased with size in all groups. 3) Size, color, and taxon nested in color significantly influenced WLR and duration of active periods in linear mixed models. 4) Hair lichen cushions had shorter active periods than growth forms with terete or flat branches due to their more open canopy architecture and lower water holding capacity (WHC). 5) WHC measured for isolated branches highly underestimated WHC for intact cushions.     

NATURAL LEVELS OF SALINE ELEMENTS IN LICHENS: DETERMINATION OF CELLULAR FRACTIONS AND THEIR IMPORTANCE AS SALINE TRACERS

Using a sequential elution procedure, the cellular location of Cl⁻, Na⁺, Mg²⁺, K⁺and Ca²⁺was determined in the lichenRamalina canariensisfrom the southwest coast of Portugal. After a dry deposition period, a logarithmic decrease in the extracellular (surface and wall-bound) concentration of Cl⁻, Na⁺and Mg²⁺was observed with increasing distance from the coast. The importance of each cellular fraction as an indication of the airborne salts was identified using factorial analysis methods, as was the relationship between the extracellular and intracellular concentration of the saline elements. The factorial analysis showed that the most important elements for the biomonitoring of airborne salinity were Cl⁻, Na⁺and Mg²⁺. However, for the cations, only the surface and wall-bound (for Na⁺) fractions seem to be related to sea-salt deposition on the lichens. The intracellular fractions of these elements are relatively independent of the surface and wall-bound concentrations, or reflect some non-linear processes induced by extreme extracellular concentrations. Although they may represent a significant proportion of the total element concentration, intracellular element concentrations are of little value in monitoring salt deposition, due to physiological control by the organism. The use of total analyses, without any fractional differentiation, can be a biased method for biomonitoring the accumulation of salt spray by lichens, because it includes the intracellular fraction, which may be independent of the deposition taking place. The use of the different cellular fractions provides a more informative indication of the deposition of atmospheric elements, while also giving information on any physiological alterations induced by the specific environmental chemical factors, including membrane damage.     

THE EFFECT OF AGRONOMIC PHOTOSYSTEM-II HERBICIDES ON LICHENS

The sensitivity ofHypogymnia physodes,Lobaria pulmonariaandPeltigera aphthosaH. physodesto six photosystem II herbicides and to DBMIB was tested in the laboratory by chlorophyll flouresence and oxygen-exchange measurements. in addition, experiments with freshly isolated photobiont cells fromH. physodesandL. pulmonariawere performed. Generally, the lichens were most sensitive to the urea herbicides diuron and isoproturon, whereas the triazines atrazine, terbuthylazine, and simazine and the triazinone metamitron wre less inhibitory. Among the three lichen species invesigated,H. physodeswas the most sensitive to the urea herbicides. For the other agents, no signifiant differences between lichen species could be found. The highest pI₅₀values obtained from dose response curves were around 6.5 for isolated photobionts, but most values for lichen thalli were in the range 5-6. Thus, there is no particular sensitivity of green algal lichen photobionts to photosytem II herbicides as compared to other algae, higher plant chloroplasts or protoplasts. In nature, we observed recovery from (damaging) treatment with 10⁻⁵mol diuron 1⁻¹forH. physodeswithin weeks. Therefore, damage to lichens fromt he use of photosystem-II herbicides in agriculture is probably only of very local occurence.     

Nutritive value of terricolous lichens for reindeer in winter

Abstract:In contrast to virtually all other species of ruminants, reindeer (Rangifer tarandus) eat substantial amounts of lichens in winter. Several different species of lichens are eaten and most are highly palatable. The chemical composition and the in vitro digestibility of six species of terricolous lichens commonly eaten by reindeer were measured. Ruminal inoculum was obtained in winter from six free-ranging reindeer that had been grazing on natural pastures in northern Norway. Analysis of the plant parts recovered from their rumens confirmed that the animals had been eating a mixed diet that included both lichens and vascular plants. The chemical composition and the in vitro digestibility of the different species of lichens varied considerably between species and genera. Cetraria islandica, C. nivalis andCladonia arbuscula were highly digestible [69–77% dry matter (DM)], Stereocaulon paschale was poorly digestible (43% DM), whereas Cladonia stellaris and C. gracilis had an intermediate digestibility (56–57% DM). Mixing Cladonia stellaris with vascular plants (50:50) had no effect on the in vitro digestibility of the combined substrates. The in vitro digestibility of Cladonia stellaris in inoculum from two captive reindeer which had had no access to lichens was very low (10% DM). This shows that the source of inoculum used for digestibility trials has a major effect on the apparent digestibility of the substrates. Evidently, the extent to which reindeer are able to utilize lichens depends on the species that are selected and on what the animals have been eating recently.     

Morphology influences water storage in hair lichens from boreal forest canopies

Hair lichens (Alectoria, Bryoria, Usnea) with high surface-area-to-mass ratios rapidly trap moisture. By photography and scanning we examined how internal water storage depended on morphological traits in five species. Specific thallus mass (STM, mg DM cm⁻²) and water holding capacity (WHC, mg H₂O cm⁻²) after shaking and blotting a fully hydrated thallus increased with thallus area. STM was ≈50% higher in Alectoria and Usnea thalli than in Bryoria. WHC was highest in Alectoria while percent water content of freshly blotted thalli was lowest in Usnea. Thallus area overlap ratio (TAO), assessing branch density of the thallus, was highest in the two thinnest Bryoria; lower in the thicker Usnea. Within species, hair lichens increased their water storage by increasing branch density rather than branch diameter. The taxonomically related genera Alectoria and Bryoria shared water storage characteristics, and differed from Usnea. Hair lichens in lower canopies have among the lowest water storage capacity reported in lichens.     

Extremotolerance and Resistance of Lichens: Comparative Studies on Five Species Used in Astrobiological Research I. Morphological and Anatomical Characteristics

Lichens are symbioses of two organisms, a fungal mycobiont and a photoautotrophic photobiont. In nature, many lichens tolerate extreme environmental conditions and thus became valuable models in astrobiological research to fathom biological resistance towards non-terrestrial conditions; including space exposure, hypervelocity impact simulations as well as space and Martian parameter simulations. All studies demonstrated the high resistance towards non-terrestrial abiotic factors of selected extremotolerant lichens. Besides other adaptations, this study focuses on the morphological and anatomical traits by comparing five lichen species—Circinaria gyrosa, Rhizocarpon geographicum, Xanthoria elegans, Buellia frigida, Pleopsidium chlorophanum—used in present-day astrobiological research. Detailed investigation of thallus organization by microscopy methods allows to study the effect of morphology on lichen resistance and forms a basis for interpreting data of recent and future experiments. All investigated lichens reveal a common heteromerous thallus structure but diverging sets of morphological-anatomical traits, as intra-/extra-thalline mucilage matrices, cortices, algal arrangements, and hyphal strands. In B. frigida, R. geographicum, and X. elegans the combination of pigmented cortex, algal arrangement, and mucilage seems to enhance resistance, while subcortex and algal clustering seem to be crucial in C. gyrosa, as well as pigmented cortices and basal thallus protrusions in P. chlorophanum. Thus, generalizations on morphologically conferred resistance have to be avoided. Such differences might reflect the diverging evolutionary histories and are advantageous by adapting lichens to prevalent abiotic stressors. The peculiar lichen morphology demonstrates its remarkable stake in resisting extreme terrestrial conditions and may explain the high resistance of lichens found in astrobiological research.     

Differentiation of embryonic stem cells into inner ear vestibular hair cells using vestibular cell derived-conditioned medium

Vestibular hair cells (V–HCs) in the inner ear have important roles and various functions. When V–HCs are damaged, crippling symptoms, such as vertigo, visual field oscillation, and imbalance, are often seen. Recently, several studies have reported differentiation of embryonic stem (ES) cells, as pluripotent stem cells, to HCs, though a method for producing V–HCs has yet to be established. In the present study, we used vestibular cell conditioned medium (V-CM) and effectively induced ES cells to differentiate into V–HCs. Expressions of V-HC-related markers (Math1, Myosin6, Brn3c, Dnah5) were significantly increased in ES cells cultured in V-CM for 2 weeks, while those were not observed in ES cells cultured without V-CM. On the other hand, the cochlear HC-related marker Lmod3 was either not detected or detected only faintly in those cells when cultured in V-CM. Our results demonstrate that V-CM has an ability to specifically induce differentiation of ES cells into V–HCs.     

POPULATION STRUCTURE OF THE EPIPHYTIC LICHENUSNEA LONGISSIMAIN A BOREALPICEA ABIESCANOPY

Usnea longissimawas sampled in SE Norway on six main branches of onePicea abies, comprising its full vertical canopy range. Nearly all specimens (n=781) were unattached and fragmented, in contrast with associated lichens. A combination of weak axes and lack of holdfasts resulted in a population of repeatedly displaced thalli, a similar situation as in ground-dwelling vagant lichens. Comparisons with a litterfall population indicated that thalli, regardless of size, had a similar probability to end as litter on the ground. Specimens were frequently sorediate, but only 12 small thalli with a basal holdfast had been directly recruited through soredial establishment. Its patchy distribution within apparently homogenous forest stands is probably a consequence of a rare successful long-range dispersal through soredia coupled with an abundant local dispersal of coarse thallus fragments. Old forests with ample, diffuse skylight at lower and humid canopy levels are probably essential to maintain a vagant epiphytic life form with a predominantly downward dispersal of thallus fragments.     

Extremotolerance and Resistance of Lichens: Comparative Studies on Five Species Used in Astrobiological Research II. Secondary Lichen Compounds

Lichens, which are symbioses of a fungus and one or two photoautotrophs, frequently tolerate extreme environmental conditions. This makes them valuable model systems in astrobiological research to fathom the limits and limitations of eukaryotic symbioses. Various studies demonstrated the high resistance of selected extremotolerant lichens towards extreme, non-terrestrial abiotic factors including space exposure, hypervelocity impact simulations as well as space and Martian parameter simulations. This study focusses on the diverse set of secondary lichen compounds (SLCs) that act as photo- and UVR-protective substances. Five lichen species used in present-day astrobiological research were compared: Buellia frigida, Circinaria gyrosa, Rhizocarpon geographicum, Xanthoria elegans, and Pleopsidium chlorophanum. Detailed investigation of secondary substances including photosynthetic pigments was performed for whole lichen thalli but also for axenically cultivated mycobionts and photobionts by methods of UV/VIS-spectrophotometry and two types of high performance liquid chromatography (HPLC). Additionally, a set of chemical tests is presented to confirm the formation of melanic compounds in lichen and mycobiont samples. All investigated lichens reveal various sets of SLCs, except C. gyrosa where only melanin was putatively identified. Such studies will help to assess the contribution of SLCs on lichen extremotolerance, to understand the adaptation of lichens to prevalent abiotic stressors of the respective habitat, and to form a basis for interpreting recent and future astrobiological experiments. As most of the identified SLCs demonstrated a high capacity in absorbing UVR, they may also explain the high resistance of lichens towards non-terrestrial UVR.     

Efficacy of a biocide tested on selected lichens and its effects on their substrata

The efficacy of Koretrel^©, a biocide used in south-eastern Asia to remove epilithic photoautotrophic organisms, was tested in the field and laboratory using lichens as target organisms. In situ observations were carried out at increasing time intervals for 6 month on 15 vegetation plots and 21 saxicolous species representative of the lichen flora of Italian monuments, selected according to their different ecology, growth-form and distribution. Change in chlorophyll fluorescence was monitored in three species for 32 day after biocide treatment. The effects of the biocide on the substratum was studied by monitoring changes in capillary water absorption and surface colorimetry of two CaCO₃-containing rocks (Aurisina limestone and Muggia sandstone), and a grey granite. Rock crystal integrity was monitored by SEM. The results show that Koretrel^© is very efficient in killing the lichens. Pronounced effects were observed in all species after 1–2 weeks, with chlorophyll fluorescence reduced to zero in 4 day in the case of Lecanora muralis and Neofuscelia loxodes and in 8 days for Caloplaca saxicola. The biocide considerably decreases capillary water absorption, and alters the surface colour of the substrata, particularly for Aurisina limestone. However, no corrosion features were observed in the rock minerals.     

The relative impact of lichen symbiotic partners to repeated copper uptake

The relative impact of lichen photobiont and mycobiont was evaluated by submitting nine lichen species with: (i) different photobiont types; (ii) different lichen growth forms; and (iii) different nutrients, pH, humidity preferences; to a range of Cu concentrations (μM) supplied in repeated cycles to simulate the natural process of uptake under field conditions. The physiological performance of the photosystem II photochemical reactions was measured using F_v/F_m and the metabolic activity of the mycobiont was evaluated using ergosterol and intracellular K-loss as indicators. Lichens with higher cation exchange capacity showed higher intracellular Cu uptake and their ecology seemed to be associated with low-nutrient environments. Thus the wall and external matrix, mainly characteristic of the mycobiont partner, cannot be ignored as the first site of interaction of metals with lichens. No common intracellular Cu concentration threshold was found for the physiological impacts observed in the different species. Most physiological effects of Cu uptake in sensitive lichens occurred for intracellular Cu below 200 μg/g dw whereas more tolerant species were able to cope with intracellular Cu at least 3 times higher. Cyanobacterial lichens showed to be more sensitive to Cu uptake than green-algal lichens. Within the Trebouxia lichens, different species showed different sensitivities to Cu uptake, suggesting that the mycobiont may change the microenvironment close to the photobiont partner providing different degrees of protection. Despite the fact that the photobiont is the productive partner, the metabolic activity of the mycobiont of lichen species adapted to environments rich in nutrients, showed to be more sensitive to Cu uptake than the photochemical performance of the photobiont.     

Contrasting changes in palatability following senescence of the lichenized fungi Lobaria pulmonaria and L. scrobiculata

Epiphytic lichens can contribute significantly to ecosystem nutrient input because they efficiently accumulate atmospheric mineral nutrients and, in the case of cyanolichens, also fix nitrogen. The rate at which carbon and other nutrients gained by lichens enters the ecosystem is determined by lichen litter decomposability and by invertebrate consumption of lichen litter. In turn, these processes are driven by the secondary compounds present in senesced lichens. Therefore, we explored how lichen palatability and concentrations of secondary compounds change with tissue senescence for Lobaria pulmonaria, a green-algal lichen with cyanobacterial cephalodia, and Lobaria scrobiculata, a cyanobacterial lichen. During senescence both lichens lost 38–48 % of their stictic acid chemosyndrome, while m-scrobiculin and usnic acid in L. scrobiculata remained unchanged. Snails preferred senesced rather than fresh L. pulmonaria, while senesced L. scrobiculata were avoided. This provides evidence that species with labile secondary compounds will have higher turnover rates, through consumption and decomposition, than those producing more stable secondary compounds.     

Culturable bacteria associated with Antarctic lichens: affiliation and psychrotolerance

Antarctic habitats harbour yet unexplored niches for microbial communities. Among these, lichen symbioses are very long-living and stable microenvironments for bacterial colonization. In this work, we present a first assessment of the culturable fraction of bacteria associated with Antarctic lichens. A phylogenetic analysis based on 16S rRNA gene sequence of 30 bacterial strains isolated from five epilithic lichens belonging to four species (Lecanora fuscobrunnea, Umbilicaria decussata, Usnea antarctica, Xanthoria elegans) shows that these represent the main bacterial lineages Actinobacteria, Firmicutes, Proteobacteria and Deinococcus-Thermus. Within the Actinomycetales, two strains group in the genera Arthrobacter and Knoellia, respectively. Most of the other Actinobacteria form well-supported groups, but could be assigned with certainty only at the family level, and one is in isolated position in the Mycobacteriaceae. The strains in Firmicutes and Proteobacteria belong to the genera Paenibacillus, Bacillus and Pseudomonas, which were already reported from lichen thalli. Some genera such as Burkholderia and Azotobacter, reported in the literature as also associated with lichens, have not been detected in this study. One strain represents the first record of Deinococcus in epilithic lichens; it is related to the species Deinococcus alpinitundrae from Alpine environments and may represent a new species. Further separated and well-supported clades indicate the presence of possibly new entities. Some of the examined strains are related to known psychrophilic bacteria isolated from ice and other extreme environments, others with bacteria distributed worldwide even in temperate climates. Most of the strains tested were able to grow at low temperatures, but tolerated a wider range of temperature. Ecological and evolutionary implications of these lichen-associated bacteria are discussed.     

Phylogeny and taxonomy of the ‘manna lichens’

We present ataxonomic revision of the ‘manna lichens’ based on morphological, chemical, ecological and molecular data. A large number of herbarium specimens and fresh collections were examined. Phylogenetic analyses were performed using nuclear ribosomal (nrITS, nrLSU) and mitochondrial small subunit (mtSSU) sequences. Some notable phenotypic characters were plotted on the phylogenetic tree, and the analysis reveals that some of these characters are useful for genus and species level distinction of certain ‘manna lichens.’ Phylogeny of the Megasporaceae was revised using a combined data set of nrLSU and mtSSU and performing parsimony and Bayesian analyses. Five genera (Aspicilia, Circinaria, Lobothallia, Megaspora and Sagedia) are recognized. Further, the relationships of five presumably closely related genera of ‘manna lichens’, namely Agrestia (vagrant), Aspicilia (crustose) Circinaria (crustose), Chlorangium (vagrant) and Sphaerothallia (vagrant) with different growth forms were analysed. The analyses revealed that ‘manna lichens’ do not form a monophyletic group but occur in different clades within the genus Circinaria. The genera Agrestia, Chlorangium and Sphaerothallia are assigned as new synonyms under the genus Circinaria and no vagrant or erratic species remain in the genus Aspicilia. The analyses also show that five new erratic, vagrant and crustose species can be recognized. In this study two ‘manna lichens’, viz. Circinaria rostamii sp. nov. (Azerbaijan, Iran and Turkey), and Circinaria gyrosa sp. nov. (Armenia, Azerbaijan, Iran, Turkey, Turkmenistan and Spain) are described as new to science. Three potentially new species with crustose and erratic forms need additional study. Aspicilia fruticolosofoliacea is reduced to synonymy under C. alpicola, and a lectotype is designated for C. aspera. Thirteen new combinations in Circinaria are presented. The phenomenon of vagrancy is briefly discussed, and the biogeography of the ‘manna lichens’ is outlined. Illustrations, distribution maps, and an identification key to the species are provided.