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.

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.

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.

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.