Lichens in the genus Platismatia are common, widespread and were some of the first to be studied by Western taxonomists. However, few molecular phylogenetic studies of Platismatia have been published to date. We present an expanded phylogeny of Platismatia inferred from 60 newly generated ITS sequences and 28 existing publicly available sequences. The new phylogeny confirms the delimitation of P. wheeleri as monophyletic and distinct from the widespread P. glauca, the latter of which was recovered as two separate, highly supported clades, that do not appear to differ in phenotype or biogeography. The western North American endemics P. herrei and P. stenophylla were not recovered as reciprocally monophyletic and may be an example of recent speciation similar to that also hypothesized for Alectoria in the same region. Ancestral state reconstructions of reproductive modes (dominant asexual vs. sexual reproduction; asexual propagule type) suggest that sexual species like P. tuckermanii can evolve from primarily asexual ancestors. Evaluation of species distributions suggests that reproductive mode may be related to range size. These data suggest that Platismatia could serve as a model for future studies on reproductive mode, biogeography and speciation in lichens.

The importance of the COI lichen herbarium is increased by the results shown here. Forty-seven taxa are reported from Africa, forty-three from Angola and seven from Mozambique. Four species are new to Africa, 30 to Angola and 3 to Mozambique. Two species are described as new to science: Parmotrema carballalianum and Sclerococcum parmotrematis, a lichenicolous fungus living on the former. A key to all known lichenicolous species of Sclerococcum growing on Parmelia s.l. is provided.

Numerous distinct clades of lichen-forming fungi have independently specialized as foliicolous colonists of living leaves in the humid tropics and subtropics. Because of technical difficulties, the anatomy of their minute crustose thalli has not been compared in detail. In the present study, we applied SEM-BSE imaging to sectioned blocks of embedded thalli representing six lecanoralean taxa of foliicolous lichen-forming fungi with unicellular green algal partners. We compared our observations with those obtained in a previous study of foliicolous Gomphillaceae (Ostropales), which utilize a similar type of algal partner. The upper surface of the thalli was a mostly continuous layer of mycobiont hyphae of typical diameter, unlike the largely acellular epilayer found previously in the foliicolous Gomphillaceae. Byssoloma leucoblepharum was exceptional in lacking a covering layer altogether. Thalli were essentially unstratified, with algal symbionts not confined to any distinct layer. Whereas the prothallus of foliicolous Gomphillaceae was derived from the overlying epilayer, in the lecanoralean taxa examined here the prothallus was derived from hyphae continuous with either the upper surface of the thallus or the lower surface, or both. This finding suggests that the prothallus of lichen forming fungi may represent structures of developmentally different origins in different taxa.

One of the two most speciose genera in the Mniaceae, Rhizomnium includes 14 to 16 named taxa with the likelihood that more remain to be described. Our previous research established that R. pseudopunctatum is an allodiploid whose haploid progenitors are R. gracile and R. magnifolium. In the course of that work, we sampled five additional species as possible progenitors. Using isozymes from starch-gel electrophoresis, we screened all eight species to compare levels of genetic variation within species, genetic distances between species, and genetic population structure. Levels of variation are generally lower than for species of Plagiomnium but are similar to those for species of Cinclidium. Relationships of species based on genetic data are mostly congruent with Koponen's (1973) “assumed phylogeny” of Rhizomnium, but there are also some clear conflicts. For example, R. appalachianum is highly divergent from the other three species placed in sect. Macromnium, and R. glabrescens does not seem to fit in sect. Rhizomnium. Genetic distance data, however, do support Koponen & Sun's (2016) recognition of R. chlorophyllosum as a separate species from R. punctatum.

Despite their global distribution moss physiology is not well understood, particularly in tropical environments. Photosynthetic Electron Transport Rate (ETR) of Hyophila involuta was measured using PAM technology. The plants were growing in a heavily shaded habitat with irregular sunflecks of full sunlight. Two models were used for estimating photosynthetic electron transport (ETR), the Waiting-in-Line and Eilers-Peeters models. Both take photoinhibition into account and gave similar results. The population studied was growing on bricks and stonework and so periodically dried out. The same species is sometimes found in waterfall environments where it is semi-aquatic. ETR_max was low at dawn, increased to an early morning maxima and then decreased during the course of the day, partially reversed by rainstorms. Mid-morning (10:30 solar time): E_opt ≈ 521 ± 77 µmol photon m^–2 s^–1 which is higher than might be expected in a shaded sun-fleck environment, ETR_max ≈ 28.3 ± 2.5 µmol e^- m^–2 s^–1 on a projected surface area basis or ≈ 57.7 ± 5.1 (µmol e^- g^–1 Chl a s^–1), photosynthetic efficiency (Alpha, α₀) ≈ 0.301 (e^- photon^–1 g^–1 Chl a). Chl a content of Hyophila was ≈ 453 mg Chl a m^–2 with Chl b/a ≈ 0.371. The O₂ electrode-based respiration rate was R = 6.78 ± 0.698 µmol O₂ g^–1 Chl a s^–1, the ETR_max is roughly equivalent to Gross photosynthesis (Pg) ≈ 14.4 ± 1.28 µmol O₂ g^–1 Chl a s^–1 (4 e^-/ O₂), so the optimum P_g/R ratio is about 2.12 ± 0.289 and net photosynthesis (P_n) is ≈ 7.62 ± 1.46 µmol O₂ g^–1 Chl a s^–1. Thus even under optimum irradiance net photosynthesis was actually rather low. pH experiments showed that Hyophila used both CO₂ & HCO₃^- inorganic carbon sources, suggesting that a concentrating mechanism (CCM) is present. Hyophila is partially homiochlorophyllous, recovering well from desiccation after 2h of lighted rehydration and recovers more after 24h but lost ≈30% of its Chl a. The moss retained its chlorophyll content if desiccated in the dark. The moss lost ≈ 2/3 of its Chl a during the monsoonal dry season.

Until a few years ago, Sphagnum magellanicum was understood to be a single widespread species with an intercontinental range. Recent work by Norwegian sphagnologists showed that S. magellanicum s.str. is restricted to southern South America and plants known as S. magellanicum in Europe should be referred to S. divinum and S. medium. In a separate publication, we showed that there are two additional major clades in eastern North America, and we describe them herein as S. diabolicum and S. magniae. These species are very hard to distinguish morphologically (and also from S. divinum and S. medium) but are distinct phylogenetically, ecologically and geographically, and are important units of biodiversity. Morphological variation within and between species is photographically documented.

Sticta is a subcosmopolitan, predominantly epiphytic lichenizing fungal genus characteristic of open sites in humid late-successional ecosystems. Recent molecular analysis has shown that the laminally isidiate species S. fuliginosa, long assumed to be well delimited, encompasses >20 phylospecies which, taken together, constitute the S. fuliginosa morphodeme. Here we elucidate the northwestern North American members of this morphodeme based on a rich sampling from throughout the Pacific Northwest regions of the U.S.A. and Canada: Alaska, British Columbia, California, Oregon and Washington. Our results support recognition of five species, three of which – S. arenosella sp. nov., S. fasciculata sp. nov. and S. torii – appear to be endemic. Of the remainder, S. globulifuliginosa was described from Colombia, while S. gretae sp. nov. occurs also in the Canary Islands and China. Two of our new species – S. fasciculata and S. gretae comprise a new phylogenetic lineage and is referred to as the S. gretae clade. New taxonomically informative thallus characters are introduced and a key to the genus Sticta in northwest North America is provided.

Schadonia saulskellyana is described as new to science based on material from the southern Appalachian Mountains in the eastern United States. The species appears to be endemic to the region and mostly restricted to the bark of conifers. It is particularly abundant and frequent in the imperiled high-elevation spruce-fir forests of the region. The new species is distinguished from its congeners by its corticolous habit, minutely areolate thallus with areoles that erupt into soralia which dissolve the areoles and give the appearance of a leprose crust, epruinose, dark brown-black apothecia with a brown hypothecium, and monosporous asci with large, muriform ascospores. It is also compared with other genera of Pilocarpaceae, particularly Calopadia. Lopadium disciforme, a superficially similar species is also compared to the new species and photographs, as well as a distribution map for eastern North America, are provided for that species.

Two competing predictions regarding highly dispersible clonal plants, such as bryophytes, expect levels of genetic diversity to either increase or decrease over time following a disturbance that opens habitat for colonization. Following up on previous research that found higher levels of genetic variation in bryophytes from relatively undisturbed forest sites, we examined unisexual, haploid species of a moss (Plagiomnium ciliare), a leafy liverwort (Porella platyphylloidea), and a thalloid liverwort (Conocephalum conicum sensu lato) from the Mountains, Piedmont, and Coastal Plain of the southeastern United States. In terms of time since last disturbance, sites were ranked Mountains > Piedmont > Coastal Plain. Measures of genetic variation, including percentage of loci polymorphic, mean number of alleles per locus, mean expected heterozygosity, and number of multilocus genotypes, all fit the prediction that genetic diversity should increase over time. We also examined several components of reproductive success expected to influence levels of genetic variation, including colony size, colony mixing, sex expression, phenotypic sex ratio, and sporophyte production (percentage of females producing sporophytes). Most, but not all, of our predictions for populations of varying time since last disturbance were fulfilled, although other ecological differences related to soil, climate, and vegetation are also likely to influence reproductive success.