Tropical mountain forests are hotspots of biodiversity that are widely threatened by human population pressure and climate change. However, the cryptogamic species richness of many tropical mountain regions is insufficiently known, the poorly understood biodiversity of tropical African lichens being a prime example. To study the diversity of the genus Peltigera (Ascomycota, Lecanoromycetes) in East Africa, we studied lichens in a wide range of habitats on the slopes of Mt Kilimanjaro in Tanzania. Ranging from savannah to alpine heath vegetation and from natural forests to agricultural environments, 13 habitat types were sampled for lichens, which were then identified based on the nuITS genetic marker and morphology. We found eight Peltigera species on the slopes of Mt Kilimanjaro, including P. alkalicola sp. nov., P. dolichorhiza, P. polydactyloides, P. praetextata, P. rufescentiformis, P. seneca, P. sorediifera and P. ulcerata. Peltigera is most common and species-rich in the subalpine Erica forest zone, and four of the eight detected species were present only in the subalpine and alpine vegetation zones. Peltigera alkalicola was identified as a previously undescribed species, growing on trachybasaltic lava in the subalpine and alpine zones of Mt Kilimanjaro. The species resembles P. lepidophora but differs by possessing smaller thalli and peltate isidia that are distinctly dark on the lighter, tomentose lamina. Based on data from the NCBI GenBank, P. alkalicola probably also occurs in Alaska (USA) and Ningxia (China). This suggests that even though the species might generally be rare, it may have a global distribution in extreme mountain environments. For the first time, we report P. sorediifera from Tanzania and P. seneca from Africa.

Recent studies have demonstrated that species boundaries among the lichen-forming fungi are in need of revision with the discovery of cryptic species in numerous clades, especially in parmelioid lichens. Here we focus on addressing the species boundaries in Canoparmelia texana, a sorediate species with a pantropical distribution that extends into temperate regions. We extracted DNA sequences of the nuclear ribosomal internal transcribed spacer region (ITS), large subunit (nuLSU) and mitochondrial small subunit (mtSSU) from samples mostly collected in Kenya, and analyzed them in a phylogenetic framework. We illustrate that our samples of the species as currently circumscribed do not form a monophyletic group but fall into two distinct clades, with the apotheciate C. nairobiensis nested within. Both of the discovered lineages have a wide distributional range and are common in Kenya, and Parmelia albaniensis C. W. Dodge is resurrected to accommodate one of the clades; consequently a new combination, Canoparmelia albaniensis (C. W. Dodge) Divakar & Kirika comb. nov., is proposed.

Additions and corrections are provided for the South African species of Graphidaceae tribe Graphideae with hyaline ascospores. Allographa oldayana I. Medeiros sp. nov. is described as new to science based on morphological, chemical and molecular data. The new species is characterized by lirellae with striate labia and a complete thalline margin, a completely carbonized excipulum, large, muriform ascospores, and the presence of hirtifructic acid. Allographa consanguinea (Müll. Arg.) Lücking, A. leptospora (Vain.) Lücking & Kalb, Diorygma aff. minisporum Kalb et al., Graphis crebra Vain., Gr. dupaxana Vain., Gr. furcata Fée, Gr. handelii Zahlbr., Gr. longula Kremp., Gr. pinicola Zahlbr., Gr. proserpens Vain, Gr. subhiascens (Müll. Arg.) Lücking and Platythecium sp. are reported as new records for South Africa. Allographa striatula (Ach.) Lücking & Kalb, Graphis analoga Nyl. and Gr. scripta (L.) Ach. are shown to be misapplied names that should be removed from the South African checklist. The new combination Mangoldia bylii (Vain.) I. Medeiros comb. nov. (bas. Graphis bylii Vain) is made; this represents an earlier name for M. atronitens (A. W. Archer) Lücking et al. Taxonomic notes are provided for Graphis bylii var. lividula Vain. and Gr. denudans Vain., species that are known only from their South African holotypes. Phylogenetic analyses that include new DNA sequence data from the nrLSU, mtSSU and RPB2 loci confirm the generic placements of several species for which molecular data were lacking: Allographa consanguinea, Glyphis atrofusca (Müll. Arg.) Lücking, Graphis crebra and Gr. subhiascens.

An investigation of the genus Usnea, in the biodiversity hotspot of the Republic of São Tomé and Príncipe in tropical West Africa, is presented here. Fifteen species, or species aggregates, were recorded for the islands: Usnea articulata aggr., Usnea baileyi (Stirt.) Zahlbr., Usnea beckeri P. Clerc & Nadel, Usnea bicolorata Motyka, Usnea erinacea aggr., Usnea exasperata (Müll. Arg.) Motyka, Usnea firmula (Stirt.) Motyka, Usnea krogiana P. Clerc, Usnea longiciliata P. Clerc & Nadel, Usnea nodulosa Swinscow & Krog, Usnea pectinata aggr., Usnea sorediosula Motyka, Usnea submollis J. Steiner, and two undetermined species. Two species of lichen are described as new to science: U. beckeri and U. longiciliata. Both species are characterized by a dense and brittle, dark green thallus, the presence of apothecia surrounded by long cilia-like fibrils, a lack of soredia, and the presence of two unknown substances; however, whereas U. beckeri has a pendant growth form and can reach 25 cm in length, U. longiciliata is differentiated by a shrubby growth form of less than 6 cm. These two species also have different ascospore dimensions. A molecular phylogenetic analysis is presented that lends support to their description as new species. Additionally, Usnea krogiana is noted as new to continental Africa and nine Usnea species or aggregates are noted as new to the Islands of São Tomé and Príncipe in the Gulf of Guinea.

This study investigated the molecular, chemical and morphological variation in the Usnea pectinata aggregate using 42 specimens, 22 from Tanzania and 20 from São Tomé and Príncipe. A total of 31 sequences (13 ITS, 13 nuLSU and 5 RPB1) were generated. The results are presented in two phylogenies: first a three-markers ‘backbone’ phylogeny for the U. pectinata aggregate, where six distinct, strongly supported subclades indicate considerable genetic variation in the dataset; and second, an ITS phylogeny with 47 terminals along with a mapping of morphological and chemistry data. Several well-supported monophyletic clades were recovered in both phylogenies and these may well represent separate species in the complex referred to here as the U. pectinata aggregate. Three morphotypes characterized by axis pigmentation and four by branch shape were noted. Six chemotypes were observed.

Of the c. 900 lichen species known from Kenya, 178 belong to the parmelioid clade. Several of these parmelioid taxa require further revisionary studies. An identification key to the species of the parmelioid clade, based on updated nomenclature, is produced to support the practical work in collecting and selecting certain parmelioid lichens for further research. A new combination Parmotrema nyasense (C. W. Dodge) R. S. Egan comb. nov. in Egan et al., Bibliotheca Lichenologica 110, 383 (2016) is published here by R. S. Egan.

Photosynthetic organisms have evolved a great variety of mechanisms to optimize their use of sunlight. Some of the clearest examples of adaptations can be seen by comparing photosynthesis in different species and in different individuals of the same species that grow under high and low light levels. While the adaptations of sun and shade higher plants have been relatively well studied, much less information is available on the photobionts of lichenized Ascomycetes. An important adaptation that can protect photosynthetic organisms from the potentially harmful effects of excess light is non-photochemical quenching (NPQ); NPQ can dissipate unused light energy as heat. Here we used chlorophyll fluorescence to compare the induction and relaxation of NPQ and the induction of electron transport (rETR) in collections of the same lichen species from exposed and from more shaded locations. All species have trebouxioid photobionts and normally grow in more exposed microhabitats but can also be readily collected from more shaded locations. Shade forms display generally higher NPQ, presumably to protect lichens from occasional rapid increases in light that occur during sunflecks. Furthermore, the NPQ of shade forms relaxes quickly when light levels are reduced, presumably to ensure efficient photosynthesis after a sunfleck has passed. The maximal relative electron transport rate is lower in shade than sun collections, probably reflecting a downregulation of photosynthetic capacity to reduce energy costs. We also compared collections of pale and melanized thalli from three species of shade lichens with Symbiochloris as their photobiont. Interestingly, NPQ in melanized thalli from slightly more exposed microhabitats induced and relaxed in a way that resembled shade rather than sun forms of the trebouxioid lichens. This might suggest that in some locations melanization induced during a temporary period of high light may be excessive and could potentially reduce photosynthesis later in the growing season. Taken together, the results suggest that lichen photobionts can flexibly adjust the amount and type of NPQ, and their levels of rETR in response to light availability.

In this study, we sampled L. pulmonaria thalli from Mt Kilimanjaro and Mt Meru, Tanzania. Across all sampled tree species, a range of 1–35 thalli of L. pulmonaria were counted per trunk (up to 5 m above ground level), with sampling distributed across 13 (c. 1 ha) plots located in the sub-alpine to montane forest altitudinal gradients of Mt Kilimanjaro and Mt Meru. Descriptive analyses were performed to determine the association of L. pulmonaria with particular host trees among the study sites and regions, and linear mixed effects models (LMM) were used to explore relationships with tree-level variables. The analyses showed that most thalli of L. pulmonaria were unevenly distributed among the tree species in the montane and sub-alpine forests of Mt Kilimanjaro and Mt Meru. Host tree characteristics such as trunk circumference, height on trunk, bark texture and trunk shape appeared to have an effect on the local population size of L. pulmonaria and the frequency of occurrence. Also, the results indicated an effect of trunk circumference and tree bark on the development of L. pulmonaria thallus size among the study sites. Furthermore, host tree species, for example, Hypericum revolutum and Rapenea melanophloeos were important habitats for L. pulmonaria on both mountains, whereas Ilex mitis, Bersama abyssinica and Hagenia abyssinica were important only on one mountain. The wider literature on L. pulmonaria ecology is also reviewed and it is therefore recommended that for successful conservation of the threatened L. pulmonaria in tropical montane forests, strategies should consider the type of the forests, together with the host tree species and their size.