Parmelioid lichens are a diverse and ubiquitous group of foliose lichens. Generic delimitation in parmelioid lichens has been in a state of flux since the late 1960s with the segregation of the large, heterogeneous genus Parmelia into numerous smaller genera. Recent molecular phylogenetic studies have demonstrated that some of these new genera were monophyletic, some were not, and others, previously believed to be unrelated, fell within single monophyletic groups, indicating the need for a revision of the generic delimitations. This study aims to give an overview of current knowledge of the major clades of all parmelioid lichens. For this, we assembled a dataset of 762 specimens, including 31 of 33 currently accepted parmelioid genera (and 63 of 84 accepted genera of Parmeliaceae). We performed maximum likelihood and Bayesian analyses of combined datasets including two, three and four loci. Based on these phylogenies and the correlation of morphological and chemical characters that characterize monophyletic groups, we accept 27 genera within nine main clades. We re‐circumscribe several genera and reduce Parmelaria to synonymy with Parmotrema. Emodomelanelia Divakar & A. Crespo is described as a new genus (type: E. masonii). Nipponoparmelia (Kurok.) K.H. Moon, Y. Ohmura & Kashiw. ex A. Crespo & al. is elevated to generic rank and 15 new combinations are proposed (in the genera Flavoparmelia, Parmotrema, Myelochroa, Melanelixia and Nipponoparmelia). A short discussion of the accepted genera is provided and remaining challenges and areas requiring additional taxon sampling are identified.

Lichens are intimate and long-term symbioses of algae and fungi. Such intimate associations are often hypothesized to have undergone long periods of symbiotic interdependence and coevolution. However, coevolution has not been rigorously tested for lichen associations. In the present study we compared the nuclear internal transcribed spacer (ITS) phylogenies of algal and fungal partners from 33 natural lichen associations to test two aspects of coevolution, cospeciation and parallel cladogenesis. Since statistically significant incongruence between symbiont phylogenies rejected parallel cladogenesis and minimized cospeciation events, we conclude that switching of highly selected algal genotypes occurs repeatedly among these symbiotic lichen associations.

Summary• The epiphyte Evernia mesomorpha forms a lichen association with green algae in the genus Trebouxia . Little is known about the population structure of E. mesomorpha. Here, population structure of the algal and fungal symbionts was examined for 290 lichen thalli on 29 jack pine ( Pinus banksiana ) trees in Manitoba.• Through phylogenetic analysis of internal transcribed spacer (ITS) nuclear ribosomal DNA (rDNA) sequences, five algal genotypes were detected that were nested within T. jamesii. Two fungal genotypes were detected that formed a clade with two other Evernia species. The genus Evernia was paraphyletic with E. prunastri , sister to Parmelia saxatilis . Restriction fragment length polymorphism (RFLP) of ITS rDNA showed multiple algal genotypes in 45% of the 290 lichen thalli collected, whereas all thalli only contained one fungal genotype.• Low population subdivision of algal and fungal genotypes among trees suggested that the algal symbiont was being dispersed in the lichen soredium.• Low fungal specificity for multiple algal genotypes and a hypothesized algal switch may be important life history strategies for E. mesomorpha to adapt to changing environmental conditions.

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Algae can tolerate a broad range of growing conditions but extreme conditions may lead to the generation of highly dangerous reactive oxygen species (ROS), which may cause the deterioration of cell metabolism and damage cellular components. The antioxidants produced by algae alleviate the harmful effects of ROS. While the enhancement of antioxidant production in blue green algae under stress has been reported, the antioxidant response to changes in pH levels requires further investigation. This study presents the effect of pH changes on the antioxidant activity and productivity of the blue green alga Spirulina (Arthrospira) platensis. The algal dry weight (DW) was greatly enhanced at pH 9.0. The highest content of chlorophyll a and carotenoids (10.6 and 2.4 mg/g DW, respectively) was recorded at pH 8.5. The highest phenolic content (12.1 mg gallic acid equivalent (GAE)/g DW) was recorded at pH 9.5. The maximum production of total phycobiliprotein (159 mg/g DW) was obtained at pH 9.0. The antioxidant activities of radical scavenging activity, reducing power and chelating activity were highest at pH 9.0 with an increase of 567, 250 and 206% compared to the positive control, respectively. Variation in the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) was also reported. While the high alkaline pH may favor the overproduction of antioxidants, normal cell metabolism and membrane function is unaffected, as shown by growth and chlorophyll content, which suggests that these conditions are suitable for further studies on the harvest of antioxidants from S. platensis.

Species delimitation in lichen-forming fungi has been based largely on morphological differences of fungal structures and the lichen thallus with an assumption that morphology reflects hereditary changes. One of the distinguishing features between Cladonia pyxidata and C. pocillum (Cladoniaceae, Ascomycotina) is the shape of the primary squamules. Because these species may inhabit different types of soil the phylogeny of these species was examined in light of potential environmental influences from soil pH and photobiont. Samples were collected across North America, and soil pH was measured for a subset of samples. The nuclear ribosomal internal transcribed spacer of 49 fungal and 14 algal partners and a portion of the polyketide synthase gene of 18 fungi was sequenced and analyzed by phylogenetic methods. Restriction fragment length polymorphism (RFLP) profiles for 129 algae were examined for geographic variation and fungal specificity. Cladonia pyxidata and C. pocillum are not monophyletic but results show seven highly supported lineages. The photobiont and geographic distribution do not play a role in species delimitation. Soil pH shows a statistically significant difference between the extreme morphologies of the two species suggesting a possible link between morphology and environmental conditions.

The lichen-forming fungal genus Cladonia P. Browne associates with green algae in the genus Trebouxia de Puymaly. Genetic structure of the algal symbionts in Cladonia gracilis (L.) Willd., Cladonia multiformis G. Merr., and C. rangiferina (L.) Nyl. was used to infer geographic patterns and symbiont associations. Algal genotypes were defined by restriction fragment length polymorphisms in the nuclear internal transcribed spacer rDNA from 115 samples of Cladonia collected from two geographic regions in Manitoba, Canada. Results suggested that two species of fungal symbiont were highly selective of the algal partner within given geographic areas, and one species was highly selective of the algal partner regardless of the geographic region. Different degrees of selectivity in three species suggested that even within the same genus, fungal selection for the algal partner may vary. In addition, DNA sequences from a subsample of 20 algal and 11 fungal specimens were used to determine phylogenetic relationships of each symbiont. Sequences of four group I intron-like insertions in the small subunit rDNA, two of which were newly reported for the genus Cladonia, were used to infer the fungal phylogeny. The intron phylogenies produced monophyletic species. Sequences of the internal transcribed spacer rDNA were used to infer the algal phylogeny. Cladonia gracilis and C. rangiferina were associated with three species of Trebouxia.Key words: selectivity, Cladonia, Trebouxia, phylogeny, geographic pattern.

Members of the Cladonia gracilis group of lichen fungi are common terrestrial lichens where morphological features are more similar between members of the C. gracilis species complex and allied species outside the complex than they are between subspecies within the complex. The objectives of this study were to examine whether the Cladonia gracilis species complex is monophyletic, to determine whether morphological similarity is supported by genetic variation, and to examine the utility of the polyketide synthase (PKS) gene for phylogenetic studies among closely related species. Two loci, the ketosynthase region of the PKS gene and the internal transcribed spacer (ITS) region of nuclear ribosomal DNA, were sequenced and analysed by Maximum Parsimony, Bayesian and haplotype network analyses. Functional differences were also inferred through ITS2 RNA secondary structures and non-synonymous changes in translated PKS amino acid sequences. The monophyly of the C. gracilis complex is supported by 71% bootstrap in the ITS phylogeny, and 92% bootstrap with greater than 95% posterior probability in the PKS phylogeny. Morphological similarity is not always supported by genetic similarity. The PKS gene is less variable than the ITS but the PKS supports species hypotheses that are reflected in the ITS2 RNA model. We conclude that monophyly of the C. gracilis complex can be supported if C. cornuta, C. coniocraea and C. ochrochlora are included in the complex. In addition, C. maxima, C. phyllophora and C. subchordalis are supported as monophyletic species outside the C. gracilis complex. Cladonia maxima may form a separate species and variation among podetial morphology may be explained by convergent evolution.