In this study we clarify the phylogeny and reassess the current taxonomy of the Micarea prasina group, focusing especially on the M. byssacea and M. micrococca complexes. The phylogeny was investigated using ITS, mtSSU and Mcm7 regions from 25 taxa belonging to the M. prasina group. A total of 107 new sequences were generated. Data were analyzed using maximum parsimony and maximum likelihood methods. The results reveal five undescribed well-supported lineages. Four of the lineages represent new species described as Micarea pseudomicrococca Launis & Myllys sp. nov., M. czarnotae Launis, van den Boom, Sérusiaux & Myllys sp. nov., M. microareolata Launis, Pykälä & Myllys sp. nov. and M. laeta Launis & Myllys sp. nov. In addition, a fifth lineage was revealed that requires further study. Micarea pseudomicrococca is characterized by an olive green granular thallus, small cream-white or brownish apothecia lacking the Sedifolia-grey pigment and two types of paraphyses up to 2 µm wide. Micarea czarnotae forms a granular, densely granular or continuous olive green thallus, convex to hemispherical apothecia often with the Sedifolia-grey pigment and no crystalline granules in the thallus. Micarea microareolata is characterized by a ± pale green areolate thallus (composed of goniocysts), cream-white apothecia lacking the Sedifolia-grey pigment and narrow spores. Micarea laeta has a vivid to olive green granular thallus, pale apothecia lacking the Sedifolia-grey pigment and wider spores compared to M. microareolata. Descriptions, images and a key are provided for the new species. Crystalline granules are introduced as a novel species-level character for Micarea.

Ten new species of Trypetheliaceae are described: Astrothelium bullatothallinum from Venezuela, which is close to A. aeneum but differs by the bullate thallus with a thick cortex, intermixed in a mosaic with the prothallus; A. cayennense from French Guiana, which is similar to A. flavomegaspermum but with a yellow pigment in the pseudostroma near the ostioles; A. diaphanocorticatum from Papua New Guinea, which has a bullate thallus with a thick hyaline cortex and 3-septate ascospores of 25–28×10–12 μm; A. macroeustomum from French Guiana, with joint lateral ostioles, UV+ yellow ostiolar region and 5-septate ascospores of 50–55×12–17 μm; A. minicecidiogenum from Costa Rica, with muriform ascospores of 70–90×20–25 μm, without pseudostromata, with solitary ascomata, lateral ostioles and an inspersed hamathecium; A. palaeoexostemmatis from Thailand, which is similar to A. exostemmatis but with larger, I+ blue ascospores; A. quasimamillanum from Brazil, with muriform ascospores of 30–33×9·5–10·5 μm, without pseudostromata, with solitary ascomata, lateral ostioles and an inspersed hamathecium; A. studerae from Brazil, with astrothelioid ascomata, lichexanthone only in the pseudostromata, 3-septate ascospores of 21·5–23·0×6·5–7·5 μm; A. tanianum from Malaysia, with a bullate thallus, solitary ascomata, covered by the thallus, (9–)11(–15)-septate ascospores, 75–100×20–22 μm; and Pseudopyrenula miniflavida from Brazil, with a yellow-inspersed hamathecium, the inspersion dissolving in KOH without colour change, and 3-septate ascospores, 15–17×5·5–6·5 μm. The unusually thick, hyaline cortical layer of the thallus of Astrothelium diaphanocorticatum, through which the individual algal cells are clearly visible, is discussed. Furthermore, 30 species are reported from 34 countries in which they had previously been unrecorded; one (Astrothelium inspersaeneum) is from a new continent, Asia.

Sixteen species of lichenicolous fungi are documented from Siphula-like lichens. Two new genera based on new species are introduced. Amylogalla Suija, Motiej. & Kantvilas, characterized by I+ blue, K/I+ violet vegetative hyphae and ascomatal wall, immersed, cleistohymenial, yellowish to orange ascomata, unitunicate, non-amyloid, 8-spored asci and hyaline, ellipsoid, aseptate ascospores, is described from Parasiphula in Tasmania. Saania Zhurb., characterized by superficial, stromatic, multilocular ascomata, non-amyloid hymenial gel, persistent periphysoids, bitunicate, non-amyloid, 4(–8)-spored asci and narrowly obovate to ellipsoid, 1(–3)-septate, initially hyaline and smooth-walled, later sometimes brown and verruculose ascospores, is described from Siphula in South Africa. Four additional species are described as new: two from Siphula (Cercidospora santessonii Motiej., Zhurb., Suija & Kantvilas and Stigmidium kashiwadanii Zhurb.) and two from Parasiphula (Endococcus hafellnerianus Motiej., Suija & Kantvilas and Pyrenidium macrosporum Motiej., Zhurb., Suija & Kantvilas). Additional hosts and/or expanded geographical ranges are reported for Aabaarnia siphulicola, Epigloea soleiformis, Plectocarpon gayanum and Pyrenidium actinellum. The Southern Hemisphere is the centre of species richness for siphulicolous fungi, with 12 species restricted to this region. Taxa recorded for the Northern Hemisphere are Sphaerellothecium siphulae (arctic and boreal) and the subcosmopolitan Epigloea soleiformis and Pyrenidium actinellum, both of which are also known from various lichen hosts. The distribution of siphulicolous fungi strongly underpins the current generic classification of Siphula-like lichens, with five species being confined exclusively to Parasiphula and nine to Siphula. A key to the taxa occurring on Siphula and Parasiphula is provided.

An ecological biogeographical perspective provides an understanding of the factors that shape the geographical distribution of organisms, their biodiversity and ecological speciation. Focusing on members of the lichen genus Solenopsora, which are strongly linked to a Mediterranean-type climate, we aimed to depict their environmental niches in the Apennine Peninsula. This area represents their ecological optima, as well as the biogeographical centre of distribution. On the basis of occurrences of Solenopsora congeners, we identified the key ecological factors that shape their environmental niches. Applying an ensemble approach, which merges the results of Random Forest, GLM and MaxEnt algorithms, suitability maps were developed. These are mainly influenced by geological substratum, temperature and precipitation. Occurrence of Solenopsora taxa seems to be mainly governed by low variability in diurnal temperature and tolerance to dryness, with precipitation in the range of 0–20 mm in the driest month and a minimum temperature of >5 °C in the coldest month. The sensitivity to diurnal temperature, an important indicator for climate change, suggests that the taxa confined to Mediterranean bioclimatic types (i.e. Solenopsora grisea, S. marina, S. olivacea subsp. olbiensis and S. olivacea subsp. olivacea) might be good indicators of climatic stability. The geological substratum was a strong limiting factor and separated the taxa into three groups: those growing on calcareous, siliceous and ultramafic substrata. Limited co-occurrence of species confined to one of the three categories suggests that the level of niche differentiation is on a microhabitat level. Accounting for ecological requirements, the taxa differ in their tolerance to sub-optimal conditions. The ecological niches of a sister subspecies pair with different reproduction strategies, fertile S. olivacea subsp. olivacea and sorediate S. olivacea subsp. olbiensis, overlap strongly. However, habitat suitability for S. olivacea subsp. olbiensis is greater in areas with higher precipitation in the driest month, whereas S. olivacea subsp. olivacea is more restricted to warmer and drier areas. We also report new regional records for Italy and the first records of S. cesatii in Serbia and Ukraine, and of S. liparina in Serbia.

Lobaria pulmonaria is a widespread epiphytic foliose lichen that exhibits a prominent reticulum, a structure that has a presumed role in mechanical support and water capture. Using photogrammetry, thallus topography was digitally modelled in three dimensions to calculate 3D surface area (A3D), which was consistently greater than areas extracted from projected images (A2D). The A3D:A2D ratio, a proxy for topographic three-dimensionality, was strongly correlated with both specific thallus mass (STM) and external water-holding capacity (WHCexternal), suggesting that the reticulum in L. pulmonaria extends hydration, photosynthetic activity and growth, following rainfall. Three-dimensionality was more pronounced in larger thalli, which is likely beneficial to liquid water-dependent internal cephalodia that occur more in older thalli and most often within the fovea.