A saxicolous species of Chiodecton and two corticolous species of Enterographa are described as new to science. Chiodecton submontanum is characterized by a saxicolous habitat, irregularly verrucose thallus, inspersed hymenium, ascospores usually exceeding 50 μm in length with 6–10 septa and the presence of roccellic acid. Enterographa sparrii has immersed, perithecioid ascomata in indistinct to slightly raised pseudostromata, 40–55 μm long ascospores with 6–9 septa and contains roccellic acid. Enterographa subcaudata has immersed, more or less round ascomata with a black disc, 35–58 μm long ascospores with 6–12(–15) septa and schizopeltic acid in its chemistry. Additionally, an identification key to the members of Roccellaceae reported so far from India is provided.

Gyalolechia fruticum, a new epiphytic species with a Mediterranean-Macaronesian distribution, is described. It differs in molecular data and in ecology from two closely related calcicolous species, G. luteococcinea and G. marmorata, both formerly called Caloplaca subochracea auct. The new species grows on coastal shrubs (rarely on wood), accompanied by species-rich communities of maritime epiphytic lichens. The typical habitat is undisturbed sand dunes, under dry conditions with frequent spells of humid air from the sea. The species is so far known from Greece, Italy, Tunisia, the Canary Islands and probably mainland Spain. We consider this conspicuous lichen an umbrella species of endangered and declining epiphytic communities of ancient shrub vegetation on well-developed sand dunes along Mediterranean coasts affected by touristic overexploitation.

Leprocaulon inexpectatum is described here as a new lichen species and the fourth member of the genus known from Europe. It is characterized by the crustose-granulose, blue-grey to bluish green thallus composed of ±discrete, soredia-like granules c. 45–70 μm in diameter, and the production of usnic acid and zeorin. Based on ITS rDNA, the lichen is closely related to the saxicolous American species L. beechingii. The new species is reported here from numerous localities in north-western Italy. It occurs on the bark of oaks, chestnut, and black locust in open deciduous forests, often in floodplain ecosystems. Our investigation of its photobiont identity using ITS, 18S and rbcL demonstrated that its symbiotic partner represents an undescribed species within the genus Symbiochloris (Trebouxiophyceae). We provide an identification key to sterile crustose sorediate lichens containing usnic acid and zeorin found in Europe.

Two new species, Placomaronea fruticosa and P. placoidea, are described. They were originally discovered in the southern Peruvian Andes at altitudes between 3000 and 4650 m. One specimen of P. fruticosa was subsequently also found among herbarium material collected in Argentina. Placomaronea fruticosa is terricolous in high altitude grasslands with rocky cliffs. It is characterized by its fruticose to subfruticose thallus, which is up to 8 mm tall and partially immersed in the substrate, its branches are bright to deep yellow, flattened and on the substrate surface their elongated apices resemble placodioid lobes of crustose species in the genus Candelina, whereas the cylindrical basal parts are pale beige to deep violet and mostly grow immersed in their substrate. The species has asci with over 20 ascospores in a 60–80 μm tall hymenium. Placomaronea placoidea is a saxicolous species, growing in rocky exposed areas. It is characterized by its tightly adnate, foliose, placodioid thallus with a bright to deep yellow upper surface. No fertile specimens were found. Both species newly described here are morphologically very similar to species of Candelina but are clearly distinguished by a cortex anatomy characteristic of Placomaronea. Cortex anatomy can thus be immensely useful to distinguish crustose and subfoliose genera in Candelariaceae, whereas secondary chemistry is shown to be quite uniform, with some chemotype variation of little taxonomic relevance. An updated ITS-only phylogeny of Candelariaceae is presented and compared with earlier phylogenies of the family. Several well-supported clades are identified, including Candelina, Placomaronea and Protocandelariella, but much of Candelaria and Candelariella s. lat. remain unresolved, and the relationships between the supported clades are not yet known. The limitations of currently available molecular data, primarily only ITS, are discussed, particularly in relation to the lack of support at species level, such as the two newly described species of Placomaronea. An updated key to currently accepted genera in Candelariaceae and all species of Placomaronea now known is provided.

A Spanish version of this abstract is provided in Supplementary Material File S1 (available online).

Using a combination of field inventories in temporary sample plots and extensive molecular analyses, the diversity of lichens in the order Teloschistales on the Commander Islands (Kamchatka Territory, Russia) was assessed. Nearly 600 specimens of the order were collected from 154 sample plots, which included 36 species, one belonging to the family Brigantiaeaceae and the rest to the Teloschistaceae; of these, 18 species belonged to the subfamily Caloplacoideae and 17 to the Xanthorioideae. The diversity of the Teloschistales is unevenly distributed across the different habitat types of the archipelago, namely coastal, tundra and floodplain. Each habitat type has a specific lichen composition and a combination of traits. Coastal habitats have the highest number of species and the greatest number of species per plot. The Commander Islands are characterized by having the highest number of Teloschistales species when compared with the most well-studied local biotas in the North Pacific. This is probably due to the presence in the archipelago of species with diverse distribution patterns, including western North American species, North-East Asian species, and endemic species, as well as species more widely distributed in the arctic-alpine and boreal regions of both Asia and North America. The putative role of the Commander and Aleutian Islands in migrations of lichens between Asia and North America is discussed. ‘Caloplaca’ litoricola and Polycauliona flavogranulosa from the Commander Islands and Orientophila corticola from the southern part of the Russian Far East are new to Russia. Three species are proposed as new to science: Athallia subrotundispora (epilithic or epiphytic lichen characterized by an inconspicuous thallus and widely ellipsoid to subglobose ascospores, 14–16(18) × 10–11 μm, with septa 6–7 μm wide), Gyalolechia orientoinsularis (corticolous lichen characterized by a yellow thallus and apothecia with a yellow to orange true exciple highly contrasting with a brown to reddish brown disc) and G. paradoxa (muscicolous or lichenicolous lichen characterized by an orange to orange-red thallus and ellipsoid to widely ellipsoid and subglobose ascospores, 12–19 × 8–13 μm, with septa 4–9 μm wide). Lendemeriella kamczatica, L. phaeocarpella and Polycauliona etesiae are new combinations. A lichenicolous morph of Lendemeriella tornoënsis is reported for the first time and a key to species of Gyalolechia s. lat. occurring in the Far East is provided.

A species new to science, Micarea svetlanae, is described from the southern part of the Russian Far East based on morphological, chemical and molecular data. This species is closely related to M. isidioprasina, which also has the micareic acid, the granular-isidiate thallus with Sedifolia-grey pigment, and crystalline granules in the hymenium and thallus, but differs in the cushion-shaped thallus, the presence of Sedifolia-grey pigment in the hymenium, numerous crystalline granules in the hymenium and hypothecium and 0–2(3)-septate ascospores. The results of the phylogenetic reconstruction place M. svetlanae in the M. prasina group. Morphological features and data on ecology, distribution and secondary metabolites are presented in detail in the paper. This new lichen species is named in honour of the Russian lichenologist Dr Svetlana Tchabanenko, who devoted her life to the study of lichens of the Russian Far East.

We describe the new lichen species Lecanora austrocalcicola from a limestone outcrop in Brazil, characterized by a verrucose thallus and small apothecia with pale discs with relatively prominent margins that are UV+ yellow, and by the presence of lichexanthone on the apothecium margin. It resembles some species of Myriolecis and Polyozosia but can be distinguished with phylogenetic analyses.

Corticolous sorediate Candelariella represent, at least in Europe, a widespread group of species, often predominant in epiphytic communities. Many specimens are challenging to identify since apothecia are generally lacking and names have been frequently misapplied in the past. Here, we studied the morphology and molecular data (ITS nrDNA sequences) of corticolous sorediate Candelariella specimens, with the aim of determining how many species occur in Europe and which names should be applied. We distinguish worldwide five taxa from this group that are widespread and currently well supported by both morphological and molecular data. These include three 8-spored species (Candelariella reflexa, C. rubrisoli and C. xanthostigmoides) and two polyspored species (C. efflorescens and Candelariella pulchella sp. nov., the latter characterized by coarser soredia, larger apothecia with a persistent proper margin and broader paraphyses tips). Four of these species (all except C. xanthostigmoides) occur in Europe. European specimens previously identified as C. xanthostigmoides belong to C. rubrisoli. Candelariella makarevichiae and C. subsquamulosa are considered synonyms of C. xanthostigmoides. Candelariella sorediosa, C. flavosorediata and C. magellanica (the latter two not reported from Europe) remain poorly known species for which molecular data is currently lacking and they require further study. Full descriptions and a key to the species discussed are provided.

Chaenothecopsis inconspicua is a new anamorphic lichenicolous fungus forming black sporodochia on the thallus of Lecanora expallens. Molecular analysis demonstrates that the new species is positioned in the Mycocaliciales. Although a remarkable diversity of anamorphs was already recognized in Mycocaliciales, it is the first species within this order known to produce sporodochioid conidiomata. Chaenothecopsis inconspicua is currently known from several localities in the northern half of the Netherlands, most often on old Quercus robur trees in villages. A key to the lichenicolous fungi inhabiting Lecanora expallens is provided.

Two new species in the genera Diploicia and Physcia are described from the tropical dry forest of Mexico. Both species are supported by morphological, chemical and molecular evidence. Diploicia edulis, a species heavily consumed by invertebrates, is characterized by lecanorine apothecia, a dull brown epihymenium not diffused by a green pigment (K−), a subhymenium conspicuously inspersed with oil droplets, and the diploicin chemosyndrome. We provide the first molecular evidence to support the inclusion of species with lecanorine apothecia in the genus Diploicia. Physcia ornamentalis, previously reported under the name Physcia undulata s. lat. as one of the main construction materials for the bags of a moth caterpillar species (Psychidae), is characterized by a frosted-pruinose thallus, soralia originating in the lobe sinuses, and by lacking soralia in the thalline margin of the apothecia.

A new species of the lichenized genus Fellhaneropsis is described from China. Fellhaneropsis sigmoidea W. C. Wang & J. C. Wei is characterized by a dispersed thallus, brown apothecia with an indistinct margin, 3-septate ascospores (14–20 μm in length), filiform-sigmoid conidia, and a foliicolous growth habit. The placement of the new species within Fellhaneropsis was confirmed by a molecular phylogenetic approach based on mtSSU sequence data. A world key to the species of the genus Fellhaneropsis is provided.

Laetisaria macrospora is a new species of lichenicolous Corticiaceae forming light pink to coral coloured basidiomata on Physcia adscendens and P. stellaris. The basidiomata are usually located on the lower surface of the host thallus and produce basidia with four sterigmata and relatively large basidiospores, 23–34 × 11–18 μm. Phylogenetic analyses using nuITS sequences fully support the placement of the new species in Laetisaria, a genus that is recovered as monophyletic. Laetisaria macrospora was discovered in the Massif Central (France) in lichen communities growing on branches of Juniperus and Genista at the summit of the Puy de Manson.

Dolichousnea longissima is famous as the world’s longest lichen, which typically reproduces asexually. Factors impacting its length and reproductive strategies are of theoretical interest and important for conservation. We discovered a Dolichousnea population with apotheciate thalli in Western China. Phylogenetic analyses using ITS sequence data confirmed specimens were D. longissima. Multiple phylogenetic branches included both apotheciate and non-apotheciate thalli, thus genetic differences within the ITS region were not related to apothecia production. There was no indication that apotheciate Dolichousnea specimens from this region belong to a separate, morphologically and genetically distinct population. In a field experiment, we transplanted non-apotheciate thallus strands of 10, 20, 40 or 80 cm length from higher to lower elevations: c. 4000 to 3400 m. Elevational gradients in temperature, relative humidity and vapour pressure deficit simulated future climatic change. We tested hypotheses regarding the impact of climatic stressors on D. longissima growth and reproduction. After three years of growth, thallus mortality was highest at the lowest sites. Of surviving thalli, 23% had fragmented, with fragmentation rates increasing with length. Other thalli thrived, reaching a maximum main stem length of 321 cm, with a maximum total length of 764 cm. Intact thalli showed negative length-dependent growth. Lower elevations were associated with initiation of sexual reproduction, reduced relative thallus length growth rates (RTLGR) and lower photobiont abundance, with apparent shifts of photobionts from the main stem to fibrils and reallocation of resources from length to central cord and fibril mass. Probability of switching to sexual reproduction increased with thallus length, but shorter thalli made greater relative investment in apothecia production. Detrimental impacts of climate change could reduce D. longissima range and biomass production, thereby also decreasing food availability for the endangered lichenivorous monkey, Rhinopithecus bieti. Conservation efforts should be prioritized at sites currently hosting abundant, fast-growing thalli, and high-elevation mature forests where D. longissima is most likely to persist under future climatic change. Apotheciate populations need protection because sexual reproduction theoretically generates genetic variability, increasing the likelihood of generating mycobiont genotypes adapted to altered climatic conditions.

The grazing impact on epiphytic lichens by a non-native gastropod species is documented and quantified for the first time in the province of Newfoundland and Labrador using a unique combination of a multiple-choice feeding design with lichen transplant techniques under controlled laboratory conditions. The feeding experiment included three arboreal lichen species sewn onto a mesh and attached to red maple sticks inside a terrarium where four Cepaea nemoralis snails were introduced and allowed to graze over a five-day period. The three lichen species used in the feeding trials included the green-algal Platismatia glauca, the cephalolichen Lobaria pulmonaria, and the cyanolichen Lobarina scrobiculata. The trials also included two sets of L. pulmonaria from different regions of the island of Newfoundland. The levels of grazing and preference by the snails was very high. Herbivory was high for all lichen species but was highest for Platismatia glauca, for which 70% of thalli were consumed after only 24 hours. Our results show that C. nemoralis is probably affecting the distribution and abundance of epiphytic lichens in the forests of Newfoundland and Labrador. Furthermore, our observations of intense herbivory on reproductive structures challenges the universal application of the optimal defence theory in lichens.

A new Philippine foliicolous species, Porina dolichoepiphylla, was discovered from the central part of Mindanao Island, and is described and illustrated here. This new species is characterized by conspicuously longer ascospores, a feature shared only with P. virescens within the Porina epiphylla subgroup but can be distinguished from the latter by its hairless surface, as well as rough thalli with primordia of perithecia. Porina dolichoepiphylla sp. nov. is known only from the type locality on Mt Kitanglad, growing along the frond of Asplenium vittaeforme in a shady lower montane forest. An updated checklist of Porina species in the Philippines with a taxonomic key to the foliicolous species of the Porina epiphylla subgroup is also provided. The discovery of the new lichen species highlights the importance of continued exploration and documentation efforts within the Philippine archipelago.

Lichens, renowned for their resilience in extreme environments, serve as valuable bio-indicators of environmental conditions. Despite this recognition, environmental influences on lichen ecophysiology are not well understood in urban environments. In this study, we explore the use of functional traits in analyzing the impact of the urban heat island (UHI) on epiphytic chlorolichens. Lichen material was collected from 12 sites across an UHI gradient in Amsterdam and Leiden, the Netherlands. For each lichen specimen, the specific thallus mass (STM) and water-holding capacity (WHC) were calculated. The relationship between the UHI and STM/WHC was assessed using linear mixed models and ANOVA. Our study provides functional trait values (STM and WHC) for 18 species for which no prior data were available. Furthermore, our findings reveal a significant correlation between the UHI and the STM, which suggests STM as a potential indicator for the UHI.

Rapid advances in species distribution modelling have been facilitated by open availability of ‘big data’ and powerful statistical methods. A key consideration remains the time window over which field recorded occurrence data are sampled to develop a baseline species distribution. Too narrow, and distributions are incomplete and affected by sampling bias, too broad and distributions may fail to meet an assumption of equilibrium, having been affected by dynamic change across a range of different predictors. Lichens are a case in point; being diverse, functionally important and the subject of bioclimatic modelling for conservation assessment, they are nevertheless a specialist taxonomic group that is comparatively less well recorded compared to birds, mammals or vascular plants, for example. In this study, we examined the distribution of the ‘hair-lichen’ Bryoria fuscescens, based on UK record data. We partitioned records into sub-decadal periods (1970s, 1990s, 2010s), and accounting for recording effort, we compared these distributions to three predictors: an historical reconstruction of two different pollutants (sulphur dioxide and nitrogen deposition), and the climate (minimum mean temperature). We asked whether the strength of evidence for the effect of environmental predictors on Bryoria fuscescens distribution varied among the different decades, while also considering a potential for lag-effects. We show that a Bryoria fuscescens distribution that appears static, is dynamic when referenced against patterns of field recording effort. Climate was consistently important in explaining Bryoria fuscescens distribution, which was also affected by the changing pattern of pollution over time. This included a lag-effect of peak sulphur dioxide in the 1970s, and accrued effects of nitrogen deposition that strengthen over time. Overall, we conclude that Bryoria fuscescens has undergone a long-term decline in extent over the last six decades, caused by complex multivariate effects of air pollution, probably combined with climate warming. The ability to resolve these trends for assessment against future conservation targets depends critically on maintaining field identification skills and a sufficiently robust recording effort.

This work attempts to better understand the significance of morphological diversity among fungal-algal contact zones present in lichens. We used TEM to examine a variety of lichen symbioses involving non-trebouxialean green algae that show intraparietal penetration by the mycobiont. A principal focus was on Endocarpon pusillum, a well-known member of a family (Verrucariaceae; Eurotiomycetes) previously reported to be characterized by unwalled haustoria exposing a naked fungal protoplast. Peg-like haustoria arose from an inner layer(s) of the mycobiont cell wall that broke through outer layers and penetrated a short distance into the wall of the green algal symbiont (Diplosphaera). In both fungal and algal cells at the contact interface, lomasome-like vesicles and tubules occurred as modifications of the plasmalemma intermixed with wall materials at the inner surface of the cell wall. A fungal cell wall was consistently present around the haustorium, which resembled those depicted in earlier TEM studies of Verrucariaceae. Previously published micrographs of Verrucariaceae purporting to show wall-less haustoria surrounded by an empty space are believed to have been misinterpreted. However, in the isidiose Porina and foliicolous Calopadia, Byssoloma and Fellhanera species (Lecanoromycetes), we did observe extreme degrees of reduction in the mycobiont cell wall at symbiont contact interfaces. In those lichens, a broad area of the fungal cell bulged into the adjacent algal symbiont, broadly invaginating the wall of the latter and penetrating it intraparietally without differentiation of a distinct haustorial structure. The mycobiont wall surrounding such protrusions often thinned to near indistinguishability towards its extremity. The protrusion made direct contact with the algal cell wall; no empty space occurred between them. We propose that the short, peg-like intraparietal haustoria bind the symbionts and help maintain cell contacts amid the stresses of tissue expansion and shrinkage, thereby avoiding disruption of the continuous hydrophobic coating that facilitates transfer between them. Broader contact interfaces with extremely thin adjacent walls may facilitate solute flow between symbionts. Reciprocal penetration of algal protrusions into mycobiont cells, noted in Porina as well as other lichens studied previously, is a neglected but potentially significant indication that both symbionts may actively work to maintain functional contact interfaces.