Individual cyanobacterial species can occupy a diversity of symbiotic lifestyles yet how this lifestyle is determined is unknown. In this study we focus on the symbiotic lifestyles of the cyanobacterial genus Nostoc, and define their lifestyle based on their symbiotic state: free-living or symbiotic with lichen-forming fungi. Within an evolutionary context, members of one symbiotic lifestyle can be found more closely related to members of another symbiotic lifestyle and do not form monophyletic groups. This pattern can be explained by either deterministic or variable factors, by whether or not switches between lifestyles occur infrequently or frequently, and by limitations on symbiont dispersal. We began this study by focusing within a single habitat in which both free-living and symbiotic Nostoc sp. individuals occur in order to test amongst hypotheses. Using the rbcLX genetic region we placed individuals within a larger phylogenetic context using a worldwide dataset of free-living and symbiotic Nostoc sp. Free-living Nostoc sp. growing at this site were distinct from co-occurring lichenized strains, but closely related to symbiotic Nostoc sp. from other continents. We expanded our sampling to a larger geographic area, including free-living Nostoc sp., as well as two additional sites in which free-living and lichenized Nostoc sp., co-occurred. We found no evidence of spatial structure on a regional scale. Based on these results, we conclude that symbiotic lifestyles within distinct Nostoc sp. lineages are determined by variable factors, and their distributions are constrained and exclude physical proximity. Finally, in the course of identifying the fungal symbionts of Nostoc we identified two species of Peltigera using ITS rDNA sequences; These species are either under-reported in Wisconsin (P. ponojensis ) or new to the U.S.A. (P. islandica).

The Acarospora strigata group is distinguished by a common phenotype of heavily pruinose areoles with deep fissures cleaving the cortex. It occurs from South and North America through Asia to Africa and Europe. One new species is described from China in Xinjiang in central Asia: Acarospora tianshanica, which produces gyrophoric acid. Acarospora interrupta is lectotypified and reported new from China. In addition, a key is supplied to the nine species currently recognized in the Acarospora strigata group.

A review of the crustose lichen genus Phlyctis in North America is presented derived from large-scale studies of chemical, morphological, and molecular data (ITS and mtSSU). Five species are recognized based on a combination of morphological and chemical characters, namely P. agelaea, P. argena, P. boliviensis, P. speirea and the newly described P. petraea. Analyses of molecular data supported the recognition of P. boliviensis and P. petraea but recovered P. agelaea, P. argena or P. speirea in a single clade with little internal phylogenetic structure, suggesting their circumscription based on reproductive mode and thallus morphology requires further study. An account is provided that includes an identification key, discussion of each species, distribution maps and illustrations of morphology. Phlyctis petraea, provisionally named more than a decade ago, is described as new to science. Molecular phylogenetic analyses using ITS and mtSSU sequence data both confirm the placement of P. petraea in Phlyctis and demonstrate two known chemotypes (one with norstictic acid and one with norstictic and stictic acids) are not reciprocally monophyletic and should be treated as variants of a single species. Psathyrophlyctis, described as a member of the Phlyctidaceae, is discussed and treated as a member of the Lecanorales incertae sedis.

A synopsis of the known lichenicolous fungi associated with Phlyctis is presented that discusses 14 species and includes an identification key. Monodictys phlyctidis is described as new to science and considered host specific on P. speirea in eastern North America.

A new species belonging to the lichen genus Physconia is described from Alaska and the Canadian and American Rocky Mountains and adjacent forested regions. It is also reported from China, Nepal, India and Siberia. The new species, Physconia labrata, is superficially similar to P. perisidiosa, but can be distinguished by having a blackened, corticate lower surface and a paraplectenchymatous upper cortex.

Anoectangium sikkimense (Pottiaceae, Bryophyta), a rare species known for China, India and Nepal, is reported from the U.S.A. in Alaska. This species, distinctive in the marginal crenulation of the shoulders of the shortly sheathing base, is new to the New World. A key is given to New World species of Anoectangium. Its serial evolutionary relationships are diagramed and discussed.

We provide a phylogenetic revision of the Pseudocyphellaria crocata complex in the Americas. Specimens traditionally identified as P. crocata, based on their cyanobacterial photobiont, yellow pseudocyphellae, at least partially white medulla, and yellow soralia or soralia-like structures, are shown to represent 13 distinct species, forming a monophyletic group divided into four large clades, three comprising one species each and one containing eight species, plus two taxa for which no molecular data are available. Seven species correspond to what was previously recognized as P. crocata and one to P. dozyana, whereas a further one is identified as the sorediate counterpart of the usually apotheciate taxon P. lechleri and another as a pseudosorediate morph of the usually phyllidiate species P. neglecta. Surprisingly, none of the species represents P. crocata s.str., which must therefore be excluded from the American lichen biota. The 13 recognized species include three species new to science and three new combinations: P. citrina (Gyeln.) Lücking, Moncada & S.Stenroos, comb. nov. [bas.: Cyanisticta citrina Gyeln., nom. nov. pro Sticta citrina Pers. nom. illeg.], P. desfontainii (Delise) Vain., P. deyi Lücking, sp. nov., P. dozyana (Mont. & Bosch) D.J.Galloway, P. epiflavoides (Gyeln.) Lücking, Farkas & Lőkös, comb. nov. [bas.: Cyanisticta epiflavoides Gyeln.], P. hawaiiensis H.Magn., P. hillii (C.W.Dodge) D.J.Galloway, P. holarctica McCune, Lücking & Moncada, sp. nov., P. lechleri (Müll. Arg.) Du Rietz, P. neglecta (Müll. Arg.) H.Magn., P. punctata Lendemer, Lücking & Moncada sp. nov., P. sandwicensis (Zahlbr.) Moncada & Lücking, comb. nov. [bas.: Sticta crocata f. sandwicensis Zahlbr.], and P. xanthosticta (Pers.) Moncada & Lücking. Based on sequenced specimens, a neotype is selected for P. citrina and epitypes for P. hawaiiensis, P. lechleri, P. sandwicensis and P. xanthosticta. A key to all sorediate or pseudosorediate species of this complex in the Americas is presented, and all species are described, discussed and illustrated.

The following five new species are described from Panama: Anisomeridium trichialis, Arthothelium isidiatum, Astrothelium flavomegaspermum, Mycocalicium chiodectonicola and Polymeridium xanthopleurothecium. In addition, 41 species are reported from Panama for the first time.

The tropical lowland rainforest is a paradise for Lejeuneaceae. Borneo is located in the heart of the biodiversity hotspots of Philippines, Sundaland and Wallacea. During an expedition to explore liverwort diversity of Sabah, Borneo we found an undescribed ocellate taxon in the lowland ultramafic rainforests. Our phylogenetic analyses based on the nuclear ribosomal ITS region and two chloroplast regions (rbcL, trnL-trnF) suggest that this unknown species belongs to the subtribe Lepidolejeuneinae of Lejeuneaceae. On the basis of the combined molecular phylogenetic and morphological data, here we propose a new genus, Thiersianthus, to accommodate this new species. Capillolejeunea known only from the East African Islands and Kymatolejeunea endemic to New Zealand were included in molecular analysis for the first time.

The tropical lowland rainforest is a paradise for Lejeuneaceae. Borneo is located in the heart of the biodiversity hotspots of Philippines, Sundaland and Wallacea. During an expedition to explore liverwort diversity of Sabah, Borneo we found an undescribed ocellate taxon in the lowland ultramafic rainforests. Our phylogenetic analyses based on the nuclear ribosomal ITS region and two chloroplast regions (rbcL, trnL-trnF) suggest that this unknown species belongs to the subtribe Lepidolejeuneinae of Lejeuneaceae. On the basis of the combined molecular phylogenetic and morphological data, here we propose a new genus, Thiersianthus, to accommodate this new species. Capillolejeunea known only from the East African Islands and Kymatolejeunea endemic to New Zealand were included in molecular analysis for the first time.