Buellia nordinii, a new muscicolous or lignicolous species characterized by a blastidiate thallus containing atranorin, apothecia with a fine granular surface, markedly enlarged paraphyses tips and large triseptate ascospores is described from Venezuela. The species grows in very humid situations near the ground in open paramo vegetation at high elevations. It is compared with other known asexually reproducing and triseptate Buellia taxa.

A new lichen species, Lecanora zeorina Li J. Li & Printzen is described here from the south-west of China. Lecanora zeorina is characterized by its somewhat areolate-squamulose thallus, zeorine to lecanorine apothecia, an epihymenium without crystals around expanded paraphyses tips, an amphithecium with large calcium oxalate crystals and the production of atranorin. A new combination, Lecanora crystalliniformis (B.G. Lee & Hur) Li J. Li & Printzen, is based on Protoparmeliopsis crystalliniformis B.G. Lee & Hur, which was described as a new species from South Korea. Collections from China are almost identical in morphology and chemistry, and are phylogenetically closely related. Phylogenetic reconstructions based on ITS and mtSSU suggest that these two lecanoroid species belong in Lecanora s. str. where they form a sister group to sorediate species such as L. barkmaniana Aptroot & Herk and L. variolascens Nyl. Detailed descriptions, discussions, distributions and phylogenetic trees, based on multiple collections, are presented.

The algicolous and lichenicolous species Psammina filamentosa is described from the Netherlands and the UK, and is characterized by long (generally over 50 μm) and somewhat tapered conidial arms. Psammina filamentosa is compared with other Psammina specimens found in the same habitat, growing on algae or lichens on the dry side of trees and stones. Psammina filamentosa, P. inflata and P. stipitata differ in the dimensions of their conidial arms. Psammina simplex, however, may be a synonym of P. stipitata, and a DNA study is needed to determine whether it is a distinct species or developing material of P. stipitata. Psammina inflata is also reported as new for the Netherlands. A new worldwide key to the 10 species of Psammina currently known is provided, including three species described from plant material.

Two new species of Bryoria are described based on morphology, chemistry and molecular phylogeny (ITS and Mcm7). Both species belong in section Bryoria, which was resolved as a polyphyletic group in the ITS+Mcm7 phylogeny. Bryoria alaskana belongs to a clade restricted to South-East Asia and north-west North America, and is so far known from south-east Alaska and the Sino-Himalayan Mountains. This highly variable species is most reliably recognized by its pendent, esorediate thallus, its production of fumarprotocetraric acid, and the combination of isotomic branching, abundant, whitish, predominantly fusiform pseudocyphellae, and sparse, short perpendicular side branches. Black emorient patches are lacking. Bryoria irwinii is endemic to north-west North America and is closely related to B. araucana from South America, B. poeltii from South-East Asia, as well as B. nadvornikiana and B. trichodes, both widely distributed in the Northern Hemisphere. It is a subpendent, esorediate species recognized by its predominantly anisotomic branching, olivaceous hue, black emorient patches, conspicuous pale brownish, fusiform pseudocyphellae, and numerous perpendicular, more or less basally constricted, side branches.

During a study of the incompletely known lichen flora of the Caucasus, we analyzed 237 specimens of corticolous Bacidia s. str. collected in the Northern and Southern Caucasus, including Armenia, Azerbaijan, Georgia, and Russia. Of these, 54 specimens belonging to 11 species of Bacidia s. str. were selected for molecular studies, representing the observed morphological variability of the genus. We obtained 142 sequences from three RNA-coding genes (nrITS, nrLSU, and mtSSU) and two protein-coding genes (RPB1 and RPB2). The single and concatenated datasets were complemented with Bacidia s. str. sequences from GenBank and subjected to Bayesian inference and two maximum likelihood analyses (RAxML and IQ-TREE). The resulting trees yielded highly concordant topologies of the groups and corresponded with previous results, supporting two main clades correlating with apothecia pigmentation. Our analyses are the first to reveal the presence of Bacidia heterochroa in the Caucasus. An exceptionally high degree of morphological plasticity was found in the Rubella and Suffusa groups. As a result of morphological examination and phylogenetic results, B. caucasica (Suffusa group) was described as new to science. Furthermore, two putative taxa in the Rubella group, Bacidia inconspicua ined. and B. maritima ined., were introduced. This study furthers our understanding and documentation of the understudied lichen flora of the Caucasus, bringing the total number of Bacidia species for the region to 13.

Porina is a widely distributed, species-rich genus of crustose, lichen-forming fungi, some with thalline outgrowths that have been recognized as isidia. We studied three taxa with thalli consisting chiefly of ascending isidioid structures occurring on trunks and branches of Taxodium in southwestern Florida, and provide details of their structure with light and electron microscopy. Two of these taxa we describe as new species: P. microcoralloides and P. nanoarbuscula. Genetic sequences (mtSSU) suggest that they are closely related to each other, yet they differ markedly in the size, morphology and anatomical organization of their isidioid branches as well as in the length of their ascospores. In the three Floridian taxa studied, the crustose portion of the thallus is partly endophloeodic and partly superficial, the latter often patchy, evanescent or inconspicuous, and completely lacks the differentiated anatomical organization characteristic of the isidioid structures arising from it. In Porina microcoralloides, the ascendant thallus consists of branched, coralloid inflated structures with phycobiont (Trentepohlia) unicells arranged at the periphery of a loose central medulla. Sparse fungal cells are interspersed and overlie the algal layer in places, but no differentiated cortex is present, leaving phycobiont cells more or less exposed at the surface. In the closely related Porina nanoarbuscula, the isidioid structures are much finer, more densely branched, and composed of a single, central file of roughly spherical Trentepohlia cells surrounded by a jacket of subglobose fungal cells. The ascospores of P. microcoralloides are more than twice the length of those of P. nanoarbuscula. Although thalli of these two Porina species occur in the same habitats and are sometimes found growing alongside each other, phylogenetic analysis of rbcL sequences suggest that they partner with distinct clades of Trentepohlia phycobionts. A third taxon examined, Porina cf. scabrida, is morphologically rather similar to P. microcoralloides, but the ascendant branches are bright yellow-orange, more cylindrical, and corticated by a thin layer of agglutinated fungal hyphae; perithecia were not seen. Analysis of mtSSU sequences places it distant from P. microcoralloides and P. nanoarbuscula phylogenetically. None of the Floridian taxa studied was particularly close to the European isidiate species Porina hibernica and P. pseudohibernica, which appeared as sister to each other in the analysis. While a particular type of isidiose structure may be reliably characteristic of specific taxa, similarities or differences in these structures do not seem to be useful indicators of phylogenetic proximity or distances among taxa. The morphological trends evident in Porina suggest that multiple transitions from crustose to isidioid or microfruticose growth have arisen repeatedly and in quite different ways within this single genus. At least some of the diverse structures treated within the broad concept of isidia may be representative of the developmental pathways by which fruticose growth forms may arise.

Arctoparmelia collatolica is described as a species new to science based on morphological, chemical and molecular data. The species is similar to the usnic acid-deficient chemotype of A. centrifuga but differs in the grey-brown to brown upper surface in the central part of the thallus and ivory white to pale brown rhizines. The species contains collatolic acid and its derivatives. Seven secondary lichen substances are reported as new for the genus Arctoparmelia. A key to Arctoparmelia taxa is provided.

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