This Special Issue is dedicated to Professor Pier Luigi Nimis on the occasion of his 70th birthday and retirement. It was our aim to publish papers addressing the three major research fields that Pier Luigi dealt with during his career: systematics and taxonomy, biomonitoring and ecology, and data resources and digitization. The papers in this Special Issue provide a vivid overview of the state of the art in the three research fields, and they reflect on Pier Luigi's outstanding contribution to lichenology. They offer a wide array of different methodologies, from the traditional approaches investigating lichen diversity and taxonomy by means of morpho-anatomical analyses, culture isolations and phylogenetic systematics, to the most modern sequencing techniques, and to the development of computer-aided tools and databases for facilitating lichen identification.

A novel species in the genus Squamulea, S. chikarensis, is described from Himalayan moist temperate forest in Pakistan. The morphology, chemistry and ITS sequences support its distinction from other species of this genus. The taxon is characterized by a pale green to yellow thallus, large apothecia up to 0.8–1.8 mm wide, pale yellow to yellow-orange apothecial discs, a hymenium 70–110 μm high, large ascospores (12–20 × 5–11 μm) and a narrow ascospore septum (1.5–3 μm). In addition, S. flakusii is reported as new to Pakistan and Eurasia.

Three new species of Arthoniales are described from Cape Verde: Ingaderia dendritica, with ascomata formed of richly branched-dendroid lirellae and containing erythrin; Sparria caboverdensis, with small stroma-like ascomata and ascospores with 3–7 transverse septa; and Syncesia miesii, with an I− thallus, a tomentose hymenial disc, and a chemistry with fatty acids only. Phylogenetic analyses using nuLSU and RPB2 sequences reveal the placement of Fulvophyton sorediatum, Llimonaea occulta, L. sorediata and Sparria caboverdensis in the family Opegraphaceae. The genus Llimonaea is recovered as paraphyletic, with L. flexuosa being placed as sister species to a lineage including the genera Ingaderia and Paraingaderia. In consequence, an enlarged concept of the genus Ingaderia is proposed, resulting in the transfer of F. sorediatum, L. flexuosa, L. occulta, L. sorediata and Paraingaderia placodioidea to Ingaderia.

This study re-examined the status of species of Diorygma Eshw. known from the Western Ghats using an integrative taxonomy approach that includes morphological and chemical data, as well as multigene phylogenetic analyses. Prior to this work, the two species D. karnatakense and D. dandeliense were distinguished primarily on lirellae morphology (branching pattern) and the number of ascospores per ascus. Our study of the morphology, chemistry and molecular phylogeny (mtSSU, LSU and RPB2) of freshly collected samples and re-examination of type material suggests that both names should be synonymized. Consequently, D. karnatakense is accepted as the correct name, with D. dandeliense as a newly proposed synonym. Phylogenetically, D. karnatakense is allied to D. antillarum and D. hieroglyphicum.

The production of anthraquinones is a major characteristic of most species in the Teloschistaceae. Other secondary metabolites are quite rare in this family, but some species are known to produce depsides, depsidones, xanthones and usnic acid. A new monotypic genus, Neoplaca, with a new species N. mirabilis, is described from the subfamily Caloplacoideae of the family Teloschistaceae, lacking anthraquinones but containing the naphthopyrans simonyellin and consimonyellin. This is the first time this class of organic compounds has been found in the family Teloschistaceae and the second in the order Teloschistales, where simonyellin has been detected in Brigantiaeaceae. Simonyellin and consimonyellin have also previously been reported in the family Roccellaceae. Neoplaca mirabilis is currently known from the two nearby localities in Yakutia, Russia, where it is common and grows on base-rich soil on exposed south-facing siliceous outcrops. The thallus consists of scattered whitish to greyish, or rarely with pale yellow tinge, squamules 1–4.5 mm diam. and 0.3–1 mm thick with citrine to orange-yellow blastidia produced from their margin; apothecia and pycnidia are unknown. In addition to naphthopyrans, N. mirabilis contains an unidentified brown pigment similar in some features to melanin. The new species is also interesting in that the pigments are apparently located inside the cells of the cortex, not on their surface, where anthraquinones are found in Teloschistaceae.

There are people who leave their mark in their field. Without doubt, Pier Luigi Nimis (for the registry office, Pierluigi; for friends, Pier; for family members, Pil; for me and a few colleagues, PL) is such a person. On the threshold of retirement but no less active than ever, Pier Luigi is about to begin a new phase of his life, a life dedicated entirely to science and, in particular, to lichenology.

The term ‘siphuloid’ is introduced for a suite of distinct lichen genera with a superficially similar foliose to fruticose morphology, notably Siphula, Siphulella, Siphulopsis, Parasiphula and Knightiellastrum. Three new species are described: Parasiphula squamosa Kantvilas (from Tasmania and New Zealand), characterized by a whitish grey, squamulose or minutely foliose thallus lacking lichen substances or containing traces of atranorin; Siphula capensis Kantvilas (from southern Africa), containing baeomycesic and squamatic acids, and characterized by robust, broadly flattened, rounded lobes with thickened apices; and S. crittendenii (from the Caribbean but with an outlying collection from Queensland, Australia), an epiphytic species containing thamnolic acid, with fragile, flattened lobes mostly to 10 mm long and 1−5 mm wide, with ragged or much-divided apices. Salient features of the species of Parasiphula are summarized and a first key for this genus is presented. Infrageneric problems in Siphula are also discussed briefly.

Lecanora caledonica is described as new to science. Molecular analyses show that it belongs to the L. intumescens group. It is also rather similar in appearance to L. intumescens, but differs mainly chemically in containing only atranorin and an unknown UV+ ice blue substance. There are also anatomical and morphological differences to the other species of the group. The new species has a pronounced oceanic distribution and is so far known only from western Norway and Scotland.

Two new species of the lichenized genus Lasioloma are described from Asia: Lasioloma longiramosum W. C. Wang & A. Abas (collected from Malaysia), is characterized by a distinct woolly prothallus between dispersed thallus patches, comparatively small, muriform ascospores, long filiform conidia (main branch 22–28 μm in length, the other three branches 65–80 μm) and a foliicolous habitat; L. verrucosum W. C. Wang & X. L. Wei (collected from China), is characterized by a warted thallus, filiform conidia (main branch 22–32 μm in length, the other three branches 50–65 μm) and a corticolous habitat. The placement of both new species was confirmed by a molecular phylogenetic approach based on combined ITS, mtSSU and mtLSU sequences, and both are compared in detail to other similar species of the genus. Our study also revealed that the length of the conidial branches, which has not been explored in previous studies, should be regarded as an important feature for species delimitation in Lasioloma.

A first integrative survey of the genus Usnea in the southern Philippines, taking into account morphological, anatomical, chemical and molecular characters, resulted in the recognition of 20 taxa, including three species new to science: Usnea angulata Ach., U. baileyi (Stirt.) Zahlbr., U. bismolliuscula Zahlbr., U. brasiliensis (Zahlbr.) Motyka, U. confusa Asah., U. croceorubescens Stirt., U. dasaea Stirt., U. himalayana C. Bab., U. krogiana P. Clerc, U. longissima Ach., U. nidifica Taylor, U. norsticornuta A. Gerlach & P. Clerc sp. nov. (characterized by a moderately thick cortex and by the presence of norstictic acid), U. paleograndisora A. Gerlach & P. Clerc sp. nov. (characterized by an orange subcortical pigmentation in the medulla, with enlarging soralia and a moderately thick and shiny cortex), U. pectinata Taylor, U. pygmoidea (Asahina) Y. Ohmura, U. rubicunda Stirt., U. rubrotincta (Stirt.) Zahlbr., U. spinulifera (Vain.) Motyka, U. subscabrosa Motyka and U. yoshihitoi P. Clerc & A. Gerlach sp. nov. (characterized by a lax medulla with non-conglutinated hyphae). Usnea krogiana is a new record for Asia; Usnea brasiliensis, Usnea confusa and U. croceorubescens are new records for the Philippines. This is the first phylogenetic study to include DNA sequences of Usnea from the Philippines. Molecular data from the ITS rDNA (76 newly generated sequences) are presented for most taxa except for U. himalayana, U. longissima and U. subscabrosa. At least six further taxa remain unidentified, awaiting the collection of additional specimens.

Microsatellite markers can provide valuable information about gene flow and population history. We developed and tested new microsatellites for the nitrophilic lichenized fungus Xanthoria parietina and studied its genetic diversity and structure within the urban area of Munich, Bavaria. We compared its local genetic pattern with that of its photobiont partner Trebouxia decolorans, for which existing microsatellites were applied. For comparison, a reference site with clean air was included in the sampling. We found support for three genetic clusters in the fungus X. parietina, which occurred intermingled in collecting sites. There was a high degree of admixture within fungal populations and individuals, and analysis of molecular variance revealed a lack of population structure in the mycobiont. The Trebouxia photobiont, in contrast, exhibited structured populations which grouped into two to five genetic clusters, and individuals showed less admixture than in the mycobiont. This indicates that the two lichen partners differ in their ability to move around in the landscape. The microsatellite markers we report are polymorphic and are suitable for population genetic studies.

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.

Urban green spaces are indispensable for the conservation of biodiversity in Germany. In addition, the availability of green areas often provides citizens with the only opportunity to experience nature. Lichens are an important component of urban environments in terms of both species diversity, and ecosystem functions and services. However, they are rarely the subject of biodiversity education. To bolster awareness on their diversity and appreciation, a transformative biodiversity education in both the formal and informal sectors is necessary. This transformative biodiversity education should not only provide knowledge about species and habitats, but also on all dimensions of biodiversity, viz., the three levels of biodiversity, drivers of biodiversity loss, and ecosystem services. For this reason, the design of biodiversity education may be particularly challenging for educators and teachers. This paper shows how biodiversity education projects on urban lichens can be developed in accordance with the principles of transformative education, supporting nature experience, knowledge transfer (species knowledge in a broad sense and interdisciplinary aspects), participation and cooperation, as well as the use of digital media. Two best-case projects, tested in Germany, are presented as examples for the design and implementation of a transformative lichen education in urban areas. A similar approach can be easily applied in other education systems beyond national boundaries.

Clypeococcum wedinii, a pyrenocarpous ascomycete growing on the lichen genus Bunodophoron in Chile and New Zealand, is described as new to science. It differs from other Clypeococcum species in the combination of the following characteristics: a conspicuous gall formation, scattered, loose to dense stromatic growths sometimes looking like a clypeus, an ascomatal wall composed of both textura intricata and angularis in surface view, a non-amyloid hymenium, an absence of ostiolar filaments, 8-spored asci, and 1-septate ascospores arranged biseriately in the ascus. An updated key to the species of the lichenicolous genus Clypeococcum is provided.

Thelocarpon periphysatum sp. nov. is described from marl quarries in the Netherlands. The species is characterized by perithecioid ascomata that have a green-yellowish ring around the ostiole, abundant periphyses and periphysoids that are up to 120 μm long, the absence of paraphyses and the wide, oblong and often somewhat asymmetrical ascospores. The perithecia are immersed in black cyanobacterial crusts on calcareous rocks. A worldwide key is provided to the 30 species of Thelocarpon that are currently accepted.

A novel lichen species occurring on rocks was collected from three different localities within Deosai National Park, Gilgit-Baltistan, Pakistan. Phylogenetic analyses of the nrDNA ITS and nuLSU regions revealed that it clustered within the genus Anamylopsora. Further chemical and morpho-anatomical analyses confirmed its uniqueness, and it is described here as a new species under the name A. pakistanica. The distinguishing characters are: an irregularly squamulose appressed thallus on rocks without rhizines; an epinecral layer up to 25 μm thick; ascospores that are hyaline, simple, thick-walled with a smooth surface; septate paraphyses with a pigmented apical cell in a gel-like matrix; globose to subglobose pycnidia with hyaline and bacilliform pycnidiospores. In particular, the species is distinguished from other members of the genus by morpho-anatomical features including the coloration of the thalli, the presence of a thick lower cortex (up to 100 μm), and the presence of simple, thick-walled ascospores. Specimens were found at altitudes up to 4587 m, the highest elevation yet reported for Anamylopsora. A key and comparison to all existing species of the genus Anamylopsora is also given.

Hair lichens are distinctive for their capillary growth and typically arboreal occurrence, especially in temperate and boreal forests. They consist of two morphogroups based on cortical pigments: a brown-black group with fungal melanin and a pale yellow-green group with usnic acid. Here we test the hypothesis that these morphogroups are ecologically distinct and thus appropriately regarded as functional groups. We examine their respective horizontal occurrence in the lower canopy of 60-year-old conifer forests on a 250 m tall volcanic cone in south-central British Columbia. Trees on open south-facing slopes and near the summit were found to support mainly melanic hair lichens (Bryoria and Nodobryoria), whereas more densely spaced trees on north-facing slopes and at the base had higher cover values of usnic lichens (especially Alectoria sarmentosa and Ramalina thrausta). The cover of melanic hair lichens was strongly correlated with canopy openness but not for their usnic counterparts. We suggest that investment in light-absorbing melanic pigments is an extreme form of specialization for high light, favouring persistence in dry, sun-exposed canopies of otherwise cool forests. By contrast, the cortex of pendent usnic hair lichens appears to facilitate optimum light transmission to underlying photobionts in shaded sites, though at the cost of sensitivity to light in open habitats, especially in rather dry regions.

Africa is an important global reservoir for biological, cultural and traditional knowledge about fungi and lichens, which are used as food, medicine and in mythology, among other things. African human populations are undergoing highly significant changes and adaptation processes, which are accompanied by rapid urbanization, meeting with western civilization, high rural migration and the loss of natural ecosystems. Indigenous knowledge is being lost, including that concerning fungi and lichens. Ethnomycology and ethnolichenology provide a diversity of knowledge about beneficial and poisonous fungi and lichens, and give insights into their sociological impact on human behaviour and use. Here we present a working and publishing environment established with the Diversity Workbench software in line with national and international initiatives for FAIR guided provision of research data. The database application called ‘EthnoMycAfrica’ contains published ethnomycological and ethnolichenological information from Africa. The content is created and curated by team partners from Central, East, West, North and Southern Africa. Data entry is performed both online and offline, optionally via a mobile device. Currently, the system with the tools DiversityDescriptions and DiversityNaviKey contains a total of 1350 well-structured and freely and openly accessible data records. EthnoMycAfrica is the first database with a data schema, standard descriptors and data content created mainly by African scholars. The data can be useful for researchers, students, conservationists, policy makers, and others. It will also provide a basis for facilitating hypothesis generation and meta-analysis.