Buellia rhizocarpica is described from Mexico. This corticolous species is characterized by a yellowish, granulose thallus, the presence of rhizocarpic acid and an unknown pulvinic acid derivative, apothecia containing large amounts of micromera-green together with yellow crystals which react K+ pinkish and by the presence of very small, Buellia-type ascospores. It grows in a well-preserved Pinus hartwegii forest at c. 4000 m altitude at the base of the volcano Popocatepetl.

A new species, Lecania belgica, is described and illustrated. It is a saxicolous lichen known only from the type locality in Belgium. It is characterized by apothecia with pruinose, irregularly undulating discs, relatively short ascospores, and by having 12–16 spores in the asci. It was found on mortar together with Diplotomma alboatrum.

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.

A key is provided to the 81 saxicolous species and infraspecific taxa of Porina Ach. (Trichotheliaceae). It includes diagnostic characters, broad distributional and some habitat information, as well as references to more complete descriptions.

Strigula macaronesica Sèrus., a new foliicolous species found in Madeira and Gomera, is distinguished by its almost linear thallus growing along leaf margins or scars and by its unusually small obclavate asci.

Two new species of Psoroma with unusual cephalodia are described: P. echinaceum with isidiate cephalodia, from southern South America and P. geminatum with fragile phyllidiate cephalodia, from New Zealand and Australia. These are additional to two previously described species producing dispersal units on their cephalodia, P. durietzii P.James & Henssen (with soredia) and P. aphthosum, Vain. (syn. nov. P. dimorphum Malme) (with isidia). This is a strategy development that ensures successful establishment of new thalli.