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Peltigera hydrophila, a new species from Chile tentatively distinguished based on phylogenetic evidence but not yet named, is formally described here. Morphological differences (e.g., non-tomentose thallus) and habitat preferences (semi-aquatic) corroborate molecular and phylogenetic distinctiveness of this early diverging lineage in section Peltigera. Due to overlapping ecological ranges, P. hydrophila shares some morphological traits with aquatic species from the phylogenetically unrelated section Hydrothyriae.

Biological soil crusts (BSCs) have important ecological functions in arid and semiarid lands, but they remain poorly understood in terms of the changes in microbial communities during BSC succession under in situ field conditions. Here, 454 pyrosequencing was used to assess the microbial community composition of four BSC types in the Tengger Desert of China: alga, lichen (cyanolichen and green alga-lichen), and moss crusts, representing early, middle, and final successional stages of BSCs, respectively. The results showed the highest diversity of microbial communities inhabiting lichen crusts, whereas the lowest diversity was observed in moss crusts. Five phyla, Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and Acidobacteria, accounted for about 72% to 87% of total prokaryotic sequences in different BSCs. The most abundant eukaryotic microorganism was Ascomycota, accounting for 47% to 93% of the total eukaryotic sequences. Along the succession of BSCs, the abundance of photoautotrophic Cyanobacteria, Chlorophyta, and Bacillariophyta declined, and that of heterotrophic microorganisms such as bacteria and fungi increased. Statistical analysis showed clear divergency of microbial taxa at the class level among the different successional stages of BSCs. The clustering results at class level showed that the moss crusts were the farthest from the rest in prokaryotic composition; the alga crusts were the most different in terms of eukaryotic microorganisms and the two kinds of lichen crusts were relatively closer in both compositions. Ordination analysis showed that the main variations of community structure among BSCs could be explained best by the abundance of Cyanobacteria and Ascomycota and by physiochemical properties of BSCs, including mechanical composition, moisture, and electrical conductivity. In conclusion, our results indicate that Cyanobacteria and Ascomycota likely play an important role in the evolution of BSC structure and functions and highlight the importance of environmental factors in shaping microbial community structures of BSCs in the Tengger Desert of China.

Premise of research. Recent high-throughput molecular analyses indicate that lichen consortia include bacterial communities, but these are not always characterized at the generic taxonomic level, a...

During lichenological explorations of tropical montane forests in Kenya, a remarkable new lichenicolous fungus was repeatedly found growing on thalli of the epiphytic tripartite cyanolichen Crocodia cf. clathrata. Molecular phylogenetic analyses placed the fungus within Gomphillaceae (Ostropales, Lecanoromycetes), a family mainly of lichen-symbiotic species in the tropics. The anatomical features (unitunicate, non-amyloid asci and simple, septate paraphyses) as well as the hemiangiocarpic ascoma development confirm its taxonomic affinity. DNA sequence data showed the closest relationship was with Gyalidea fritzei, followed by Corticifraga peltigerae. A monotypic genus, Taitaia, is introduced to incorporate a single species, T. aurea. The new fungus is characterized by aggregated ascomata with yellow margins and salmon red discs developing from a single base.

Plants and biological soil crusts (biocrusts) are the key producers in drylands, but biocrusts seldom show net CO2 uptake. I hypothesized that biocrusts could augment CO2 fixation by incorporating plant-derived carbon. I collected biocrusts located at the base of Gutierrezia sarothrae (C3 forb), Bouteloua gracilis (C4 grass), and from bare interspaces between plants, and from a mesocosm experiment with live B. gracilis or dead B. gracilis roots. To trace carbon sources, I determined 13C values of the biocrust community, isolated cyanobacteria and lichen, and plant leaves because the photosynthetic pathway distinguishes the tissue 13C values. Biocrust communities and washed cyanobacteria and cyanolichen in G. sarothrae microsites were depleted by ~2‰ relative to other locations. Biocrust δ13C did not differ between the interspace and live or dead B. gracilis. Potential mechanisms for the trend in biocrust δ13C adjacent to C3 plants include differences in microsite conditions, biocrust communities, use of respired CO2 in the soil matrix for photosynthesis, or mixotrophic use of plant photosynthates. Further investigation of this observation may improve understanding of the degree to which the activities of dryland primary producers are coupled.

Non-rainfall water (NRW), as the most frequent water source of drylands, is significantly boosted by biocrusts. However, the mechanism of biocrustal promotion and utilization of NRW have been little studied. In this paper, the NRW accumulation patterns, photosynthetic activities and CO2 exchange of different biocrusts (2 cyanobacteria crusts-ACs, 1 cyanolichen crust-LC1, 1 green algae lichen crust-LC2, and 1 moss crust-MC) under NRW were studied through in situ mesocosm experiments in the Hobq Desert of China during the autumns of 2014 and 2015. Structural equation models showed that crustal properties feedback affected the degree of meteorological parameters on NRW accumulation, in which the effect of surface temperature gradually decreased with the development of biocrusts while that of subsoil temperature and light intensity increased. As for the sources, ca. 50% of NRW in ACs derived from subsoil but more than 78% from atmosphere in LCs and MC, and this pattern was obviously influenced by the recovery degree of photosynthetic activity. But the diel maximum NRW (NRWmax) were mainly determined by crust thickness, photoautotroph biomass and other properties. During NRW accumulation, the recovery of photosynthetic activity in ACs was the earliest, followed by that of LC2 and MC, LC1 never recovered. Whereas, the initial CO2 exchange of ACs and MC were often earlier than that of LC2, and the minimum diel NRWmax required by ACs, LC2, and MC to maintain carbon balance were ca. 0.08, 0.17, and 0.20 mm, respectively. Thus we proposed the application boundary of inoculation-based technology in drylands is the areas where the diel NRWmax exceed or equal 0.08 mm and carbon input under NRW last more than 2 h during NRW-abundant seasons.

Background and AimsIn order to re-establish lichen symbiosis, fungal spores must first germinate and then associate with a compatible photobiont. To detect possible establishment limitations in a sexually reproducing cyanolichen species, we studied ascospore germination, photobiont growth and photobiont association patterns in Pectenia plumbea.MethodsGermination tests were made with ascospores from 500 apothecia under different treatments, and photobiont growth was analysed in 192 isolates obtained from 24 thalli. We determined the genotype identity [tRNALeu (UAA) intron] of the Nostoc cyanobionts from 30 P. plumbea thalli from one population. We also sequenced cyanobionts of 41 specimens of other cyanolichen species and 58 Nostoc free-living colonies cultured from the bark substrate.Key ResultsNot a single fungal ascospore germinated and none of the photobiont isolates produced motile hormogonia. Genetic analyses revealed that P. plumbea shares Nostoc genotypes with two other cyanolichen species of the same habitat, but these photobionts were hardly present in the bark substrate.ConclusionsDue to the inability of both symbionts to thrive independently, the establishment of P. plumbea seems to depend on Dendriscocaulon umhausense, the only cyanolichen species in the same habitat that reproduces asexually and acts as a source of appropriate cyanobionts. This provides support to the hypothesis about facilitation among lichens.

We studied the genotype diversity of cyanobacterial symbionts in the predominately terricolous cyanolichen genus Peltigera (Peltigerales, Lecanoromycetes) in Estonia. Our sampling comprised 252 lichen specimens collected in grasslands and forests from different parts of the country, which represented all common Peltigera taxa in the region. The cyanobacteria were grouped according to their tRNA(Leu) (UAA) intron sequences, and mycobiont identities were confirmed using fungal ITS sequences. The studied Peltigera species associated with 34 different "Peltigera-type" Nostoc trnL genotypes. Some Peltigera species associated with one or a few trnL genotypes while others associated with a much wider range of genotypes. Mycobiont identity was the primary factor that determined the presence of the specific Nostoc genotype within the studied Peltigera thalli. However, the species-specific patterns of cyanobiont selectivity did not always reflect phylogenetic relationships among the studied fungal species but correlated instead with habitat preferences. Several taxa from different sections of the genus Peltigera were associated with the same Nostoc genotype or with genotypes in the same habitat, indicating the presence of functional guild structure in the photobiont community. Some Nostoc trnL genotypes were only found in the Peltigera species of moist and mesic forest environments, while another set of Nostoc genotypes was typically found in the Peltigera species of xeric habitats. Some Nostoc trnL genotypes were only found in the Peltigera taxa that are common on alvars and may have specialized to living in this unusual and threatened habitat type. (C) 2018 Elsevier Ltd and British Mycological Society. All rights reserved.

Organisms have evolved different cellular mechanisms to deal with environmental stress, primarily through complex molecular mechanisms including protein refolding and DNA repair. As mutualistic symbioses, lichens offer the possibility of analyzing molecular stress responses in a particularly tight interspecific relationship. We study the widespread cyanolichen Peltigera membranacea, a key player in carbon and nitrogen cycling in terrestrial ecosystems at northern latitudes. We ask whether increased temperature is reflected in mRNA levels of selected damage control genes, and do the response patterns show geographical associations? Using real-time PCR quantification of 38 transcripts, differential expression was demonstrated for nine cyanobacterial and nine fungal stress response genes (plus the fungal symbiosis-related lec2 gene) when the temperature was increased from 5 °C to 15 °C and 25 °C. Principle component analysis (PCA) revealed two gene groups with different response patterns. Whereas a set of cyanobacterial DNA repair genes and the fungal lec2 (PC1 group) showed an expression drop at 15 °C vs. 5 °C, most fungal candidates (PC2 group) showed increased expression at 25 °C vs. 5 °C. PC1 responses also correlated with elevation. The correlated downregulation of lec2 and cyanobacterial DNA repair genes suggests a possible interplay between the symbionts warranting further studies.

A new cyanolichen,Peltigera islandicasp. nov. in the sectionPeltigera(‘P. caninagroup’) is described from Iceland. This species is similar in general appearance toP. rufescensandP. membranacea, but may be recognized by its downturned lobe tips and narrow lobes, respectively. Most thalli are bright emerald green in colour when moist, although a dark khaki green colourmorph is also documented. Monophyly ofP. islandicas. lat. (i.e. includingP. sp. AsensuO’Brienet al., from Canada) is significantly supported based on ITS sequences and corroborated by molecular synapomorphy (absence of the ITS1 hypervariable region). Analysis of therbcLX locus indicates the cyanobiont ofP. islandica(Nostocsp.) comprises strains belonging to a pool of Icelandic genotypes, some of which are present in otherPeltigeraspecies, includingP.“neorufescens”, another taxon new to Iceland collected during this study. Association with photobionts that are shared by other local species suggestsP. islandicamay be well established in Iceland, but a review of herbarium collections as well as broader field surveys are needed to better characterize its geographical distribution.

Erioderma pedicellatum, an enigmatic boreal cyanolichen epiphyte is sympatric with the widespread pantropical cyanolichen Coccocarpia palmicola in cool and damp forests in Atlantic parts of Canada. After sampling co-occurring specimens of these lichens in Newfoundland, we quantified important hydration traits. We hypothesized that 1: these lichens restricted to wet forests have higher internal water holding capacity (WHCinternal) than what humid air and dewfall can provide, and 2: the rare E. pedicellatum has higher WHCinternal and / or WHCtotal than the widespread C. palmicola. Both hypotheses were supported: Mean WHCinternal across a wide thallus size range was 0.26 and 0.35 mm H2O in C. palmicola and E. pedicellatum, respectively; corresponding mean WHCtotal were 0.73 and 0.86 mm. These high WHC-levels could only be filled by liquid hydration sources. Because WHC strongly increased with thallus size, larger specimens needed even more water (1.7 mm), emphasizing these species’ dependency on rain and thus wet forests.

Ephebe brasiliensis is a semi-aquatic fruticose cyanolichen that occurs in freshwater environments from Brazil (Minas Gerais and São Paulo states) and Uruguay. Although this species may be locally abundant and has "wide" distribution, it has been poorly studied and is still misunderstood with respect to their distribution and ecological characteristics. Herein, E. brasiliensis is reported for the first time in Southern Brazil.

In this study, we investigated responses of the Photochemical Reflectance Index (PRI), and Normalized Difference Vegetation Index (NDVI) to gradual dehydration of several Antarctic lichen species (chlorolichens: Xanthoria elegans, Rhizoplaca melanophthalma, Physconia muscigena, cyanolichen: Leptogium puberulum), and a Nostoc commune colony from fully wet to a dry state. The gradual loss of physiological activity during dehydration was evaluated by chlorophyll fluorescence parameters. The experimental lichen species differed in thallus color, and intrathalline photobiont. In the species that did not exhibit color change with desiccation (X. elegans), NDVI and PRI were more or less constant (mean of 0.25, − 0.36, respectively) throughout a wide range of thallus hydration status showing a linear relation to relative water content (RWC). In contrast, the species with apparent species-specific color change during dehydration exhibited a curvilinear relation of NDVI and PRI to RWC. PRI decreased (R. melanophthalma, L. puberulum), increased (N. commune) or showed a polyphasic response (P. muscigena) with desiccation. Except for X. elegans, a curvilinear relation was found between the NDVI response to RWC in all species indicating the potential of combined ground research and remote sensing spectral data analyses in polar regions dominated by lichen flora. The chlorophyll fluorescence data recorded during dehydration (RWC decreased from 100 to 0%) revealed a polyphasic species-specific response of variable fluorescence measured at steady state—Fs, effective quantum yield of photosystem II (ΦPSII), and non-photochemical quenching (qN). Full hydration caused an inhibition of ΦPSII in N. commune while other species remained unaffected. The dehydration-dependent fall in ΦPSII was species-specific, starting at an RWC range of 22–32%. Critical RWC for ΦPSII was around 5–10%. Desiccation led to a species-specific polyphasic decrease in Fs and an increase in qN indicating the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts and N. commune cells. In this study, the spectral reflectance and chlorophyll fluorescence data are discussed in relation to the potential of ecophysiological processes in Antarctic lichens, their resistance to desiccation and survival in Antarctic vegetation oases.

The importance of N2-fixing arboreal cyanolichens to the nitrogen (N)-balance of sub-boreal interior hybrid spruce (Picea glauca × engelmannii) and subalpine fir (Abies lasiocarpa) forests was examined at field sites in central BC, Canada. Host trees were accessed by a single-rope climbing technique and foliage as well as arboreal macrolichen functional groups were sampled by branch height in eight random sample trees from each of two high (High Cyano) and two low (Low Cyano) cyanolichen abundance sites for a total of 32 sample trees. Natural abundances of stable isotopes of N (15N, 14N) and carbon (13C, 12C) were determined for aggregate host tree and epiphytic lichen samples, as well as representative samples of upper organic and soil horizons (Ae and Bf) from beneath host trees. As expected, N2-fixing cyanolichens had 2–6-fold greater N-contents than chlorolichens and a δ15N close to atmospheric N2, while foliage and chlorolichens were more depleted in 15N. By contrast, soils at all trees and sites were 15N-enriched (positive δ15N), with declining (not significant) δ15N with increased tree-level cyanolichen abundance. Lichen functional groups and tree foliage fell into three distinct groups with respect to δ13C, the tripartite cyanolichen Lobaria pulmonaria (lightest), host-tree needles (intermediate), and bipartite cyanolichens, hair (Alectoria and Bryoria spp.) and chlorolichens (heaviest). Branch height of host trees was an effective predictor of needle δ13C. Our results showed a modest positive correlation between host tree foliage N and cyanolichen abundance, supporting our initial hypothesis that higher cyanolichen abundances would elevate host tree foliar N. Further study is required to determine if high cyanolichen abundance enhances host tree and/or stand-level productivity in sub-boreal forests of central BC, Canada.

We explore relative growth rates (RGRs) and carbon-based secondary compounds (CBSCs) in epiphytic lichens along height-above-the-ground gradients. The chlorolichen (Letharia vulpina (L.) Hue), the cephalolichen (Lobaria pulmonaria (L.) Hoffm.), and the cyanolichens (Lobaria hallii (Tuck.) Zahlbr., Nephroma helveticum Ach.) were attached to branches at 0.5–3.0 m heights of young spruce trees transplanted for 1 year in forest gaps and in old meadows of an inland valley in British Columbia. Cephalolichen and cyanolichen RGRs were highest in forest gaps, whereas the chlorolichen grew faster in meadows with twice as much light as forest gaps. Transplantation height did not influence lichen temperature or RGRs, despite height-dependent light increases. CBSCs were highest in the chlorolichen (13%), followed by the cephalolichen (5%) and the cyanolichens (1% and 0%). CBSC concentrations increased with thallus size, and were significantly higher in forest gaps mainly for L. pulmonaria. Only one minor CBSC in each species varied with height. The slow growth of cephalolichen and cyanolichens in meadows is consistent with these lichens’ preferences for forested habitats. Cold air ponding from snow-capped mountains was probably strong enough to form enough nocturnal dew to support reasonable lichen growth at all heights. The high species-specific and the low habitat-specific CBSC variations are consistent with constitutive CBSC defense levels in studied lichens.

The widespread cyanolichen genus Peltigera comprises many insufficiently known poorly delimited and/or undescribed species. Phylogenetic analysis of 252 Peltigera specimens from a wide range of habitat types in Estonia revealed 31 putative taxa (OTUs). Multivariate analysis revealed habitat-specific segregation between the Peltigera species along a gradient from humid eutrophic forests to dry oligotrophic forests and grasslands and along a soil pH gradient from alkaline soils of alvar grasslands to acidic soils of conifer forests. The diversity of Peltigera was the highest on roadsides and dunes and the lowest in alvar habitats which, however, supported the unique assemblage of undescribed Peltigera taxa. Deciduous broad-leaved forests, too, included several undescribed or rare and red-listed species. The results demonstrate that in Estonia many Peltigera species have narrow habitat requirements and are at present threatened by habitat loss and degradation.

Cyanolichens are an assemblage of fungi and cyanobacteria from diverse, cosmopolitan habitats. Typically composed of a single species of cyanobacterium, with or without another eukaryotic alga, here we present two novel cyanobionts isolated from an undescribed tripartite lichen. This endolithic lichen was isolated from a granite cemetery tombstone from Jacksonville, FL, and contains two potentially nitrogen-fixing cyanobionts. Employing a total evidence approach, we characterized the cyanobionts using molecular (the 16S rDNA and ITS gene region), morphological, and ecological data. Phylogenetic analyses revealed two novel taxa: Brasilonema lichenoides and Chroococcidiopsis lichenoides, both of which fell within well-supported clades. To our knowledge, this represents the first instance of a tripartite lichen with two cyanobacterial and no eukaryotic members. These types of lichens may well represent an unexplored reservoir of cyanobacterial diversity. The specific epithets are proposed under the provisions of the International Code of Nomenclature for algae, fungi, and plants.

Lichen symbioses are defined as a symbiotic relationship between a mycobiont (generally an ascomycete) and one or more photobionts (green algae or/and cyanobacteria). It was proposed that cephalodia emancipation is an evolutionary driver for photobiont switch from chlorophyte to cyanobacteria. In this study we want to test the monophyly of cyanolichens and to measure the phylogenetic signal of the symbiotic relationship between cyanobacteria and a mycobiont partner in the lichen genus Pseudocyphellaria. This genus includes some species that have a chlorophyte as primary photobiont (and Nostoc in internal cephalodia), while others have only cyanobacteria. In a phylogenetic framework we measure the phylogenetic signal (or phylogenetic dispersion) as well as mapped photobiont switches performing stochastic character mapping. Results show that having cyanobacteria as main photobiont has a strong phylogenetic signal that follows a Brownian motion model. Seven clades in the phylogeny had an ancestor with cyanobacteria. Reversal to a green algae photobiont is rare. Several switches were estimated through evolutionary time suggesting that there was some flexibility in these traits along the phylogeny; however, close relatives retained cyanobacteria as main photobiont throughout the cyanolichen’s history. Photobiont switches from green algae to cyanobacteria might enhance ecotypical differentiation. These ecotypes could lead to several speciation events in the new lineage resulting in the phylogenetic signal found in this study. We give insights into the origin of lichen diversity exploring the photobiont switch in a phylogenetic context in Pseudocyphellaria s. l. as a model genus. Fil: Vidal Russell, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Messuti, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina

Vertical distribution, biomass abundance and nitrogen stocks of epiphytic macrolichens were examined in the two dominant tree species, interior hybrid spruce (Picea engelmannii Parry ex Engelm. x glauca (Moench) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.), in sub-boreal spruce forest ecosystems of central British Columbia. Lichens were contrasted between two different site types containing either high (High Cyano) or low (Low Cyano) epiphytic cyanolichen abundance. A single rope technique was used for canopy access and a ‘clump’ method was used to estimate the abundance of arboreal lichens at different heights within both canopy tree species for five functional groups: Bryoria spp., Alectoria sarmentosa, foliose chlorolichens, bipartite cyanolichens, and Lobaria pulmonaria (the only tripartite cyanolichen). In this way, the relationship between average lichen biomasses and tree height for each tree species were assessed. We determined that biomass was dependent on tree height and species, with a greater abundance of lichen appearing on fir trees (mean ± SD; 1588 ± 428 g tree−1) than the generally taller spruce trees (917 ± 422 g tree−1). Foliose chlorolichen biomass was more abundant in trees with low abundance of L. pulmonaria (777.1 ± 365.9 g tree−1) than those with a high abundance of L. pulmonaria (553.6 ± 400 g tree−1). Much of this increase in chlorolichen biomass in trees with low cyanolichen abundance was a result of greater chlorolichen abundances in lower canopy positions where cyanolichens would otherwise predominate. Although bipartite cyanolichens had a higher %N (∼3.2%N) than L. pulmonaria (2.3%N) of dry mass, there was a much higher abundance of L. pulmonaria in the canopy of High Cyano sites containing a larger amount of N (4.04 ± 0.95 kg N ha−1) than in all bipartite cyanolichens combined (2.33 ± 1.11 kg N ha−1) or any other lichen spp. Chlorolichens are poor competitors for lower branch positions when cyanolichens such as L. pulmonaria are abundant, the latter of potential importance for N inputs into N-limited sub-boreal forests of central BC.

Lichens result from symbioses between a fungus and either a green alga or a cyanobacterium. They are known to exhibit extreme desiccation tolerance. We investigated the mechanism that makes photobionts biologically active under severe desiccation using green algal lichens (chlorolichens), cyanobacterial lichens (cyanolichens), a cephalodia-possessing lichen composed of green algal and cyanobacterial parts within the same thallus, a green algal photobiont, an aerial green alga, and a terrestrial cyanobacterium. The photosynthetic response to dehydration by the cyanolichen was almost the same as that of the terrestrial cyanobacterium but was more sensitive than that of the chlorolichen or the chlorobiont. Different responses to dehydration were closely related to cellular osmolarity; osmolarity was comparable between the cyanolichen and a cyanobacterium as well as between a chlorolichen and a green alga. In the cephalodium-possessing lichen, osmolarity and the effect of dehydration on cephalodia were similar to those exhibited by cyanolichens. The green algal part response was similar to those exhibited by chlorolichens. Through the analysis of cellular osmolarity, it was clearly shown that photobionts retain their original properties as free-living organisms even after lichenization.

Photosynthesis was compared in two cyanobacterial lichens (Lobaria hallii and Peltigera praetextata) and two green algal lichens (Lobaria pulmonaria and Peltigera leucophlebia) exposed to red, green or blue light. Cyanolichens had substantially lower photosynthetic CO(2) uptake and O(2) evolution than the green algal lichens in blue light, but slightly higher photosynthesis in red and green light. The effective quantum yield of photosystem (PS) II (Φ(PSII)) decreased with increasing red and green light for all species, but in blue light this response occurred in green algal lichens only. Cyanolichen Φ(PSII) increased with increasing blue light at low irradiances, but decreased at stronger exposures. However, after adding red light the efficiency of blue light for photosynthetic O(2) evolution increased by 2.4 times. Because phycobilisomes associated with PSII have a low blue light absorption, our results are consistent with blue light absorption mainly by Chl in PSI. Thereby, unequal allocation of excitation energy between PSII and PSI results in low cyanolichen photosynthesis under blue light. This is new knowledge in the science of lichenology with important implications for e.g. the reliability of using Chl fluorometers with blue light for cyanolichens.

Spilonema was originally described to accommodate an unusual group of cyanolichens with thread-like, cushion-forming thalli, and has long been placed in Coccocarpiaceae based on ascomatal development. However, Spilonema is the only genus of Peltigerales to include species lichenized with the cyanobacterial genus Stigonema, and the evolutionary relationships of Spilonema to other genera in the family have yet to be tested using molecular data. We present evidence from combined nuclear 28S, 18S and mitochondrial 12S rDNA to confirm the placement of the core species of Spilonema (S. paradoxum and S. revertens) in Coccocarpiaceae. Our data further show that despite possessing a different genus of photobiont (Scytonema), the north Pacific endemic genus Spilonemella must be included within Spilonema, suggesting that closely related species of the genus have changed photobionts in the course of evolution. However, we recovered Spilonema dendroides, one of the only lichens known to associate with the cyanobacterial genus Hyphomorpha, as only distantly related to the Coccocarpiaceae. The evolutionary relationships of this species are as yet unclear but it may occupy a basal position in the Peltigerales. We create for this species the new genus Erinacellus T. Sprib., Muggia & Tønsberg.

Molybdenum (Mo) nitrogenase has long been considered the predominant isoenzyme responsible for dinitrogen fixation worldwide. Recent findings have challenged the paradigm of Mo hegemony, and highlighted the role of alternative nitrogenases, such as the vanadium-nitrogenase. Here, we first characterized homeostasis of vanadium (V) along with other metals in situ in the dinitrogen fixing cyanolichen Peltigera aphthosa. These lichens were sampled in natural sites exposed to various levels of atmospheric metal deposition. These results were compared with laboratory experiments where Anabaena variabilis, which is also hosting the V-nitrogenase, and a relatively close relative of the lichen cyanobiont Nostoc, was subjected to various levels of V. We report here that V is preferentially allocated to cephalodia, specialized structures where dinitrogen fixation occurs in tri-membered lichens. This specific allocation is biologically controlled and tightly regulated. Vanadium homeostasis in lichen cephalodia exposed to various V concentrations is comparable to the one observed in Anabaena variabilis and other dinitrogen fixing organisms using V-nitrogenase. Overall, our findings support current hypotheses that V could be a more important factor in mediating nitrogen input in high latitude ecosystems than previously recognized. They invite the reassessment of current theoretical models linking metal dynamics and dinitrogen fixation in boreal and subarctic ecosystems.

In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.

In the revegetation region of Shapotou (at the southeastern edge of Tengger Desert), biological soil crusts (BSCs) generally develop and succeed from cyanobacterial soil crusts (CSCs) to lichen soil crusts (LSCs). Based on the different dominant lichens on crust surface, LSCs were further divided into cyanolichen soil crusts (CLSCs) and green algae lichen soil crusts (GLSCs). In this study, the microstructures and photosynthetic diurnal changes in both CLSCs and GLSCs were investigated using the microscopic observation and chlorophyll fluorescence techniques. The results showed the different types of LSCs have different surface morphological characteristics and inner structures due to the different biological compositions. Compared with the CLSCs, GLSCs had a higher photosynthetic efficiency, including the maximum photosynthetic efficiency (Fv/Fm) and effective photosynthetic efficiency (Phi(PSII)), which in the final analysis was considered to be closely correlated with the different photosynthetic characteristics between different photobiont types (green algae and cyanobacteria). In addition, similar to CSCs, a midday depression of photosynthetic efficiency was detected in LSCs, although the depression extents were different in different types of LSCs. In conclusion, the occurrence of midday depression of photosynthetic efficiency might be a stress effect and also an adaptation strategy of LSCs to adversity, especially the high light intensity and temperature at noon. (C) 2013 Elsevier Masson SAS. All rights reserved.

Acetone-extractable carbon based secondary compounds (CBSCs) were quantified in two epiphytic lichens to study possible effects of external factors (season and aspect) on secondary chemistry and to relate defense investments to biomass growth and changes in specific thallus mass (STM). At the end of four separate annual cycles starting in each of the four seasons, the cyanolichen Lobaria scrobiculata and the cephalolichen Lobaria pulmonaria (green algae as the primary photobiont and with localized Nostoc in internal cephalodia) were monitored in their natural forest habitats and after being transplanted at three contrasting aspects in open sites. Season strongly influenced most CBSCs. Medullary CBSCs in both species were twice as high in summer as in winter. Aspect hardly affected major CBSCs, whereas transplantation from forest to clear-cut slightly reduced these compounds. No major CBSCs in any species showed a trade-off with growth rate. Dry matter- as well as thallus area-based medullary CBSC contents increased with STM. The cortical usnic acid strongly increased with growth rate and followed spatial, but not seasonal variations in light exposure. Maximal CBSC levels during seasons with most herbivores is consistent with the hypothesis inferring that herbivory is a major selective force for CBSCs. Lack of trade-off between growth and defence investments suggests that these two processes do not compete for photosynthates.

Foliose lichens with cyanobacterial bionts (bipartite and tripartite) form a distinct assemblage of epiphytes strongly associated with humid microclimatic conditions in inland British Columbia. Previous research showed that these cyano- and cephalolichen communities are disproportionately abundant and species-rich on conifer saplings beneath Populus compared to beneath other tree species. More revealing, lichens with cyanobacterial bionts were observed beneath Populus even in stands that did not otherwise support them. We experimentally test the hypothesis that this association is due to the interception of glucose-rich nectar that is exuded from Populus extra-floral nectaries (EFN). Using CO2 flux measurements and phospholipid fatty acid (PLFA) analysis with experimental applications of 13C6-labeled glucose, we demonstrate that cyano- and cephalolichens have a strong respiratory response to glucose. Lichens treated with glucose had lower net photosynthesis and higher establishment rates than control thalli. Furthermore, lichens with cyanobacterial bionts rapidly incorporate exogenous 13C into lichen fatty acid tissues. A large proportion of the 13C taken up by the lichens was incorporated into fungal biomarkers, suggesting that the mycobiont absorbed and assimilated the majority of applied 13C6 glucose. Our observations suggest that both cyanolichens and cephalolichens may utilize an exogenous source of glucose, made available by poplar EFNs. The exogenous C may enable these lichens to become established by providing a source of C for fungal respiration despite drought-induced inactivity of the cyanobacterial partner. As such, the mycobiont may adopt an alternative nutritional strategy, using available exogenous carbon to extend its realized niche.

Cryptogamic species and their associated cyanobacteria have attracted the attention of biogeochemists because of their critical roles in the nitrogen cycle through symbiotic and asymbiotic biological fixation of nitrogen (BNF). BNF is mediated by the nitrogenase enzyme, which, in its most common form, requires molybdenum at its active site. Molybdenum has been reported as a limiting nutrient for BNF in many ecosystems, including tropical and temperate forests. Recent studies have suggested that alternative nitrogenases, which use vanadium or iron in place of molybdenum at their active site, might play a more prominent role in natural ecosystems than previously recognized. Here, we studied the occurrence of vanadium, the role of molybdenum availability on vanadium acquisition and the contribution of alternative nitrogenases to BNF in the ubiquitous cyanolichen Peltigera aphthosa s.l. We confirmed the use of the alternative vanadium-based nitrogenase in the Nostoc cyanobiont of these lichens and its substantial contribution to BNF in this organism. We also showed that the acquisition of vanadium is strongly regulated by the abundance of molybdenum. These findings show that alternative nitrogenase can no longer be neglected in natural ecosystems, particularly in molybdenum-limited habitats.

Summary Development of the symbiotic association in the bipartite lichen Pseudocyphellaria crocata was investigated by characterizing two regions of the thallus. Thallus organization was examined using microscopy. A HIP1-based differential display technique was modified for use on Nostoc strains, including lichenized strains. Northern hybridization and quantitative real-time polymerase chain reaction were used to confirm differential display results, and determine expression levels of key cyanobacterial genes. Photosystem II yield across the thallus was measured using pulse-amplitude modulated fluorescence. Microscopy revealed structural differences in the thallus margins compared with the centre and identified putative heterocysts in both regions. Differential display identified altered transcript levels in both Nostoc punctiforme and a lichenized Nostoc strain. Transcript abundance of cox2, atpA, and ribA was increased in the thallus margin compared with the centre. Expression of cox2 is heterocyst specific and expression of other heterocyst-specific genes (hetR and nifK) was elevated in the margin, whereas, expression of psbB and PSII yield were not. Structural organization of the thallus margin differed from the centre. Both regions contained putative heterocysts but gene expression data indicated increased heterocyst differentiation in the margins where photosystem II yield was decreased. This is consistent with a zone of heterocyst differentiation within the thallus margin.

International audience; Mycosporine-like compounds, comprising mycosporines and mycosporine-like amino acids (MAAs) are UV protecting secondary metabolites described in organisms such as fungi, algae, cyanobacteria or animals. Lichens however, were only poorly investigated for such constituents so far. Here, a method for the characterization of mycosporines and MAAs in purified aqueous extracts, involving HPTLC coupled to spectrophotodensitometry, HPLC-DAD-MS(n) and UPLC-HRMS analysis, is described. This optimized protocol was validated on three algae and one cyanolichen containing known MAAs and mycosporines, and then applied to 18 cyanolichen species. Analyses revealed the presence of five already described mycosporine-like compounds in the investigated species, including mycosporine serinol in Lichina and Peltigera species and mycosporine glutamicol in Degelia plumbea. Apart from that, eight unknown mycosporine-like compounds were detected and tentatively characterized on the basis of their DAD spectra and their MS(n) and HRMS data: two in the alga Porphyra dioica and six in cyanolichen species belonging to the genera Degelia, Nephroma and Stereocaulon. From Nephroma laevigatum, the mycosporine hydroxyglutamicol was preparatively isolated and identified through HRMS, 1D and 2D NMR spectroscopic data. The optimized analytical protocol allowed the characterization of mycosporine-like compounds in small amounts of material and confirmed the potential of cyanolichens as a source of mycosporine compounds. It should also be applicable to investigate lichen species with green algae photobionts for mycosporine-like compounds.

Previous research in phosphorus-fertilized Hawaiian montane forests has demonstrated that cyanolichens respond to elevated canopy phosphorus (P) availability by increasing in abundance and diversity; a similar but more muted response is seen for chlorolichens and mosses. In this study, I ask whether P also controls cyanolichen abundance in five unfertilized Hawaiian forests, four on the island of Kauai and one on Hawaii. In three of the four Kauai sites, trees which hosted abundant cyanolichens had significantly higher foliar P content than trees with sparse cyanolichen growth. In the Hawaii site, both foliar P and bark P content were significantly higher on high-cyanolichen cover trees (0.074% vs. 0.053% for leaves, p < 0.001, and 0.085% vs. 0.035% for bark, p < 0.001). Chlorolichen and bryophyte abundance were best predicted by cyanolichen abundance at three out of four of the Kauai sites. These results suggest that host tree P content may be an important factor controlling the abundance of cya...

Alder-dominated riparian forests represent only a small proportion of the landscape in central-interior British Columbia. However, they possess a suite of attributes that may allow them to function as refugia for canopy macrolichens. These include their deciduous habitat, their location in moist nutrient receiving sites, and their distribution as narrow corridors that cross broad regional landscapes. We have examined their potential role as lichen refugia by assessing canopy macrolichen communities in 75 riparian alder forests across a 200 km longitudinal gradient in central-interior British Columbia. Study sites were stratified equally between three climate subzones of the Sub-Boreal Spruce biogeoclimatic zone. Forty-nine macrolichen taxa were observed, including the old-growth indicator cyanolichen species Lobaria scrobiculata (Scop.) DC., L. retigera (Bory) Trevisan, Nephroma isidiosum (Nyl.) Gyelnik, and Sticta limbata (Sm.) Ach. Canonical correspondence analysis identified mean annual temperature, mean annual precipitation, age of adjacent conifer forest, and abundance of large stems (dbh >10 cm) as significant explanatory variables. Regional precipitation gradients explained the exclusion of many lichen species from both the most westerly and most easterly riparian forests, with drier summer conditions and heavy winter snowpack, respectively, being major limiting factors. Lichens preferentially occupied large leaning stems, which may provide greater precipitation interception and continuity of substrate, when compared with smaller upright alder stems. We conclude that alder-dominated riparian forests represent a major refugium for old-growth dependent lichens in British Columbia’s sub-boreal spruce landscapes and as such may provide valuable dispersal corridors between remnant old-growth coniferous forest patches.

The composition and abundance of lichen communities on conifer saplings beneath five overstorey tree species were compared at three subboreal forest site types in east-central British Columbia. Site-level differences in lichen communities were attributed to different levels of moisture and light limitations in the understorey. At sites with adequate moisture and light, cyanolichens were uniformly abundant and species rich on conifer saplings beneath different understorey species. However, at sites with moisture or light limitations, cyanolichens were more abundant and species rich on conifer saplings beneath overstorey Populus than on saplings beneath other overstorey tree species. Cyanolichen communities also showed greater species richness on conifer saplings beneath the Populus canopy than on the trunk of Populus itself. Differences in calcium, phosphorus, molybdenum, and manganese availability in throughfall precipitation failed to explain much of the variation in lichen community structure. These results suggest that Populus can facilitate cyanolichens under sub optimal moisture or light conditions by providing some, as yet unknown, factor that is critical to their establishment and growth.

Macroclichen and bryophyte species diversity, abundance, biomass and nitrogen stocks were compared between arboreal and terrestrial habitats in old-growth sub-boreal spruce forests in central British Columbia, Canada on the two most common soil types in the area, fine- and coarse-textured soils. A total of 118 macrolichen and bryophyte species were identified, including 71 species of macrolichens (44 arboreal and 43 terrestrial) and 47 species of bryophytes, of which only one moss (Orthotrichum sp.) was arboreal. Macrolichen functional groups varied in both diversity and abundance between arboreal and terrestrial communities. Cyanolichens were common in both arboreal and terrestrial habitats, but were much more abundant arboreally than terrestrially. This epiphytic biomass was largely attributed to the tripartite cyanolichen species, Lobaria pulmonaria, while the most common terrestrial macrolichens were bipartite Peltigera cyanolichen species. From a biomass perspective, the epiphyte community w...

Lichens are hosts for a variety of lichenicolous fungi. By investigating two lichens with specialized parasites, we will test the hypothesis that these parasites reduce lichen fitness by increasing the palatability of their respective hosts. The palatability of Lobarina scrobiculata and Lobaria pulmonaria with or without galls of the lichenicolous fungi, Plectocarpon scrobiculatae and P. lichenum, respectively, were quantified in a feeding-preference experiment with grazing snails (Cepaea hortensis). We repeated the experiment for pairs with or without gall in which the carbon-based secondary compounds (CBSCs) had been reduced nondestructively by acetone rinsing. Lichens with galls had lower concentration of CBSCs than those without, but this contrast disappeared after acetone rinsing. In the lichen high in nitrogen (N) (the cyanolichen L. scrobiculata), the grazing was low, and the snails did not discriminate between specimens with and without Plectocarpon-galls. In L. pulmonaria low in N (green algae as main photobiont), the parasite reduced the lichen C : N ratio and the snails strongly preferred specimens with Plectocarpon-galls, regardless of whether CBSC concentration had been reduced or not. In conclusion, some lichen parasites can indirectly reduce lichen fitness by increasing its palatability and thus the grazing pressure from snails, whereas other parasites do not affect grazing preferences.

The suitability of the cyanolichen Peltigera praetextata (Sommerf.) Zopf as indicator of the effects of air pollution around a cement industry was investigated. For this purpose, lichen samples taken from an unpolluted site were exposed for 1–6 months at selected sites (a cement mill, two quarries, inhabited and agricultural sites) in SW Slovakia: physiological parameters and ultrastructural features were examined prior and after exposure. The responses of P. praetextata were then compared with those of the green-algal lichens Evernia prunastri and Xanthoria parietina co-located at the same sites. The performance of the cyanobacterial photobiont of P. praetextata (as reflected by the maximum quantum yield of primary photochemistry FV/FM and by the performance index PIABS) was negatively influenced mainly by the length of exposure in the urban and agricultural sites and less by dust pollution around the cement mill and the quarries. A significant increase in membrane lipid peroxidation products reflected the effects of oxidative stresses in all sites. The alteration of the content of water soluble proteins was detected in the samples exposed around the cement mill, while dehydrogenase activity did not show any significant pattern. Similarly to green algal lichens, ultrastructural alterations featured lipid droplets increase, swelling of cellular components, thylakoid degeneration and sometimes plasmolysis, which on the whole gave the cells an aged appearance, especially in the urban and agricultural sites. On the whole, E. prunastri confirmed to be the most sensitive to dust pollution, P. praetextata was likely influenced by microclimatic conditions and habitat eutrophication and X. parietina was the most resistant. When compared with green-algal lichens, P. praetextata was not the best indicator of the effects of cement dust pollution.

Nitrogen-fixing epiphytes (especially lichens with a cyanobacterial symbiont-cyanolichens) have the potential to contribute significant amounts of nitrogen (N) to montane tropical forests, which are typically low in N-but the factors controlling the abundance and distribution of epiphytic cyanolichens are poorly understood. In long-term fertilization experiments in montane forests on a 4.1 million-yr-old Oxisol on the island of Kaua' i and on a 152-yr-old lava flow on the island ofHawai'i, the epiphytic cyanolichen Pseudocyphellaria crocata increased significantly in abundance in canopies of host trees fertilized with phosphorus (P). There was no response to fertilization with N or other essential elements. Nitrogen-fixation rates were also elevated in lichens in P-fertilized plots at both sites. Phosphorus supply to host trees may be an important factor controlling N inputs to montane tropical forests by N-fixing epiphytes.

In the boreal forest landscape, aspen has been effectively selected against in favour of conifers. The decrease in aspen is of particular concern since it has more host-specific species associated with it than any other boreal tree species. Recently forest management systems have begun to include green-tree retention in order to maintain structural diversity. We initiated this study in order to investigate whether retained aspen trees provide suitable habitats for epiphytic lichens and, if so, whether this varies according to species characteristics, such as morphology and photobiont. We chose to investigate the abundance and vitality of five species: three foliose cyanobacterial lichens (Collema curtisporum, Collema furfuraceum and Leptogium saturninum) and two crustose green-algal lichens (Biatora epixanthoides and Mycobilimbia carneoalbida). These lichens were examined on aspen within forest stands and on remnant aspen in clear-cuts at eight localities, in northern Sweden. Our results show that the response to exposure following clear-felling differs between species according to their morphology. The two crustose lichens were more abundant in the forest stands compared to the clear-cuts. In the clear-cuts, they mainly occurred on the northern sides of the trunks. Even 24 years after cutting, the three cyanolichens were equally or even more abundant on trees in the clear-cuts than in the forest stands. However, they were mainly found on the northern sides of the remnant aspen. We suggest that remnant aspen trees may function as suitable substrate and as stepping stones for colonisation of new stands, at least for the cyanolichens studied here.

Dinitrogen (N2)-fixing lichens (cyanolichens) have long been recognized as a source of exogenous N in various ecosystems, yet the effects of nitrogen inputs from these lichens have been little studied. Cyanolichens of the genus Peltigera Willd. are often the dominant members of the earth-dwelling (terricolous) cyanolichen community. They occur in diverse habitats around the globe, but no studies of their influence on soil N have been reported. We conducted field and laboratory investigations with the primary objective of determining whether soil N availability is increased near healthy thalli of terricolous dinitrogen-fixing lichens. We measured available soil N in situ with ion-exchange resin bags, potentially mineralizable N with laboratory incubations, total soil N, and soil temperature. Measurements were taken along transects that extended away from thalli of Peltigera, perpendicular to and parallel to topographic contours. Studies were conducted in ten types of forest across northern Minnesota, including two contrasting sites that represent extremes of habitat for Peltigera. Soil N availability, potentially mineralizable N, and soil %N increased significantly with proximity to healthy thalli of Peltigera (P-values

Dark respiration (DR) of lichens is reported to be higher in species with a high photosynthetic potential (suggesting a metabolic maintenance cost effect) and also, often in laboratory studies, transiently after photosynthesis (suggesting a substrate-driven effect). We investigated the occurrence of the latter, the effect of diurnal net photosynthesis (NP) on subsequent nocturnal DR, under natural temperate climate conditions in the chlorolichens Lecanora muralis and Cladonia convoluta and the cyanolichen Collema cristatum. Data sets totalling 15 months, 106 and 113 days, respectively, were obtained from automatic cuvettes that continually measured CO2 exchange and ambient conditions at 30 min intervals. For each 24 h period (sunrise to following sunrise), several measures of NP and DR were extracted, including maximal and mean rates and daily sums. No statistically significant correlations between the various measures of DR and preceding NP were found for L. muralis, only one weak correlation for Co. cristatum (the means of DR and NP) and three for Cl. convoluta (sums and means of DR and NP). It is proposed that even these significant correlations are actually a result of embedded codependencies between NP, DR and thallus water content. Overall it is concluded that no substrate-driven dependency of DR on preceding NP under natural conditions could be recognised. The periods of desiccation that often occur between the NP and following DR as well as the wide range of combinations of conditions would certainly contribute to this lack of relationship.

The assertion that the blue-greens (‘cyanobacteria’) are bacteria and not algae has led to alternative concepts for both of the latter terms. Bacteria is now often used to designate the prokaryote kingdom, that includes the blue-greens, while in other contexts it means specifically those prokaryotes that are not blue-greens. The term algae, on the other hand, has no biosystematic implications; it encompasses many phylogenetically independent lineages characterized by oxygen-evolving photosynthesis. The algal status of the blue-greens is therefore not compromised by their classification among the bacteria. Current lichenological terminology, however, reflects the view that the blue-greens are not algae, thereby diverging from the concept of algae employed in phycology. The purpose and utility of terms that group organisms according to structural, functional and ecological criteria are insufficiently appreciated. These concepts do not compete with phylogenetic/biosystematic classifications, but rather complement them.

A galactomannan was isolated from the cyanolichen Leptogium azureum via successive alkaline extraction and precipitation with Fehling solution. The structure of the polysaccharide was investigated using NMR spectroscopy, methylation analysis, Smith degradation, and HPSEC-MALLS. As galactomannans from other lichens species, the polymer obtained presents a (1→6)-linked main chain of α-mannopyranose, substituted preferentially at O-2 by α-Manp or β-Galp non-reducing ends. As observed in previous investigations, the C-1 region of the 13C-NMR of these heteropolysaccharides are typical of some lichens species, and can be used as fingerprints in chemotaxonomy. However, in despite of the general structure in common, the substitution level of this structure and their content of mannose is higher than of the others galactomannans obtained of lichenized fungi contained the green alga of the genus Trebouxia.

The cyanolichen genus Epiphloea is currently included within the Heppiaceae (Lichinomycetes) based on ascus characteristics. The presumed presence of a prototunicate ascus has been used as support for this classification, despite the incongruence with other characters (e.g. spores). Here, we use a molecular phylogeny of the two markers mtSSU rDNA and Mcm7 to investigate the position of Epiphloea. In addition, we have re-investigated the ascus characteristics. Our results place the two species, Epiphloea byssina and E. terrena, within the Collemataceae, nested in Leptogium s. str. The ascus type in both species is shown to be Lecanoralean and similar to the ascus in other Collemataceae, with a strongly amyloid tube-like structure. This observation supports the placement within Lecanoromycetes and refutes the earlier suggested affinities with Heppiaceae and Lichinomycetes. The correct names for these species are Leptogium byssinum and Leptogium terrenum.

Abundant canopy lichen communities characterize wet-temperate rainforests on the windward slopes of interior mountain ranges in north-central British Columbia, Canada. Historically, these forests have regenerated through gap-dynamics; however, our knowledge of lichen colonization within gaps is limited. We have now compared lichen biomass on regenerating trees in naturally occurring 1–3 ha gap-disturbances (these gaps presumed to have originated from insect out-breaks in the late 1800's) with those on regenerating trees of similar age growing in the understory of the surrounding old growth forest. Only small differences were seen in total lichen biomass on regenerating trees between the two settings, however, analysis of the individual lichen groups (Alectoria, Bryoria, Foliose, and Cyanolichen) revealed striking differences. The Bryoria group was 35% more abundant on gap trees (632 g/tree) and was distributed vertically through a larger proportion of the tree crown. The Cyanolichen functional gr...

Summary • Cyanobacteria were isolated from bipartite cyanolichen species of Pseudocyphellaria and the identity of the major photobionts established. The specificity of the cyanobacterial–fungal association was also examined. • Comparison of 16S rRNA gene sequences distinguished cyanobacterial and green algal isolates, and both 16S rRNA gene and tRNALeu (UAA) intron sequences of isolates and lichen thalli identified candidate photobionts. In addition, the genetic diversity of both the cyanobiont and mycobiont was investigated using the comparison of tRNALeu (UAA) intron sequences and ITS sequences, respectively. • The 16S rRNA gene sequences identified two species-specific photobionts with similar sequences; however, the tRNALeu (UAA) intron sequences unambiguously discriminated between the two symbiotic cyanobacterial strains. Moreover, the fungal ITS sequences of the two corresponding lichens, Pseudocyphellaria crocata and Pseudocyphellaria neglecta, showed little variation. • The cyanobacterial–fungal associations of P. crocata and P. neglecta were specific for all samples. However, the similarity of the ITS sequences raised the possibility that they represent the same species and that their different morphology is influenced by the cyanobacterial symbiont.