The genus Scoliciosporum includes crustose lichens characterized by gelatinized, branched and anastomosing paraphyses, Lecanora-type asci, and hyaline, usually septate ascospores. During investigations of crustose lichens in the Canadian Arctic, we discovered a distinctive, previously undescribed species of the genus occurring on terricolous bryophytes, an unusual substratum for the genus. Scoliciosporum quajautik is further characterized by its well-developed thallus, large apothecia with a persistent margin, fusiform 0–1-septate ascospores, and a pigmented hypothecium that produces a magenta effusion with potassium hydroxide solution. Phylogenetic analyses based on four loci (mtSSU, LSU, ITS and RPB2) place the species within a well-supported Scoliciosporum clade, confirming its generic placement despite its atypical morphology and ecology. The new species is currently known from five collections from Nunavut and northern Québec, all from lichen-rich tundra near the boundary between the Northern and Southern Arctic ecozones. In addition, we discuss the status of Catillaria muscicola and Stereocaulon cumulatum in the North American Arctic and conclude that Catillaria muscicola is known only from the type collection from Greenland whereas Stereocaulon cumulatum is present and probably widespread.

A molecular phylogeny of the genus Sporopodium was inferred from concatenated ITS, mtSSU and nrLSU sequences using maximum likelihood and Bayesian phylogenetic analyses, focusing on material from tropical Asia. A highly supported monophyletic group was recovered as the S. asianum group, characterized by pruinose apothecia or containing epithecial algal cells. Five species belonging to this group are described as new to science from Asia: S. album W. C. Wang & J. C. Wei, with small white apothecia with a loosely farinose margin; S. asianum W. C. Wang & A. Abas, with khaki apothecia, a K+ yellow epithecium and a K+ orange thallus; S. chebalingensis W. C. Wang & J. C. Wei, with a green thallus, bright yellow campylidia, epithecial algal cells and a white apothecial margin; S. flavomarginale W. C. Wang & Ek Sangvichien, with a bluish grey thallus, bright yellow campylidia, pruinose apothecia with epithecial algal cells, and a yellow margin; and S. pruinosum W. C. Wang & J. C. Wei, with a yellowish green thallus, brown campylidia, apothecia with a greyish green disc and a yellow margin. These findings point towards Sporopodium being a genus with a high degree of unrecognized diversity.

Nine species and one variety of lichenicolous fungi are reported on Megaspora verrucosa var. verrucosa. Of these, five species and one variety are described as new to science: Arthonia aspiciliae var. megasporae, with black, epruinose, superficial ascomata, a brownish grey, I+ red hymenium, brown, K+ greyish to olivaceous epihymenium and hypothecium, non-capitate paraphysoids lacking a dark apical cap, and hyaline, heteropolar, 1-septate, non-halonate ascospores; Leptosphaeria verrucosae, with epapillate ascomata, well-developed periphysoids and long interascal filaments, 2-spored asci, and olivaceous buff, 3-septate, comparatively large ascospores up to 55 μm long; Merismatium subnigritellum, with ascomata mainly 150–220 μm diam. and (sub)muriform ascospores mainly 14–18 × 8–9.5 μm, showing (6–)8–11(–18) cells in optical section; Polycoccum megasporae, with finally verrucose, 1(–3)-septate, comparatively large ascospores up to 44 μm long; Stigmidium kudratovii, growing on the apothecial discs of the host, with abundant, macroscopically conspicuous, dark vegetative hyphae, pseudoparaphyses of ‘type a’, hyaline, 1-septate, smooth-walled, non-halonate, BCr− ascospores, and lacking paraphysoids; and Talpapellis ochirbatae, with abundant superficial hyphae, relatively short, occasionally branched conidiophores, and (0–)1(–2)-septate conidia in short chains. A presumably undescribed taxon of Lichenostigma subgen. Lichenogramma growing on the same host, with relatively sparse, scarcely ramified plurihyphal vegetative strands, 1–3-septate ascospores, and thalloconidia, is characterized. A key to the 17 species of lichenicolous fungi reported on Megaspora verrucosa is provided.

Lichens have long been recognized as indicator species of environmental health and microclimate stability because they passively regulate their internal water status. Rather, lichens modulate their environment-to-internal water status relationships through structural adaptations in the thallus. Pseudocyphellae, breaks in the upper and lower cortex that expose the medulla, are present across unrelated lineages of lichens. However, they have rarely been studied from a functional physiological perspective in the tropical ecosystem, an ecologically important yet understudied biome. To understand the role of traditionally measured thallus-related traits (thickness, area, specific mass and water holding capacity) and pseudocyphellae-related traits (size and density) in regulating water status, we investigated the tropical lichen Crocodia aurata (Peltigeraceae) at three sites situated along a precipitation gradient in Monteverde, Costa Rica. We hypothesized that drying rate (k) is predicted by differences in water availability along a natural precipitation gradient, and that thallus and pseudocyphellae traits drive variation in k across this gradient. To test this hypothesis, we calculated the drying rate and measured thallus traits in 60 thalli across three sites spanning ~600 m of elevation and differing by 1000–1500 mm in annual precipitation. Consistent with ecophysiological theory, which suggests that lichens in wetter habitats will dry faster to maintain a favourable, intermediate water status, we found that samples of Crocodia aurata from wetter sites dried significantly faster than those from drier sites. All traditionally measured thallus traits predicted drying rate while pseudocyphellae-related traits did not significantly predict drying rate. This suggests that pseudocyphellae may not play a primary role in regulating the drying process in Crocodia aurata, in response to water availability along a tropical precipitation gradient. Instead, traditionally measured thallus traits remain the dominant drivers of drying rates. These findings contribute to our understanding of the acclimation of lichens to different climatic conditions and emphasize the complex interaction between environmental factors and morphological traits. Studying water relations and corresponding functional traits of these poikilohydric organisms is critical if we are to understand how these ecologically important organisms interact with their environments as a function of specific functional traits, and hence understand future impacts of changing climates.