Fiona Ruth Worthy

Based on a combination of morphological, chemical, and phylogenetic analyses, we present a new revision of the lichen genus Pleopsidium in China. Pleopsidium tumidulumsp. nov. and P. corrugatulumsp. nov. are proposed as new species to science, both included in a distinctive clade (clade 1) together with P. gobiense. These three species are characterized by the absence of fatty acids, acaranoic and acarenoic acids, and share similar ecological traits. In contrast, species containing fatty acids, including Pleopsidium flavum, P. chlorophanum, and P. discurrens, constitute a separate clade (clade 2). Fresh specimens of Pleopsidium discurrens were collected from the type locality, Yulong Snow Mountain, and molecular data were generated to confirm the phylogenetic position of the species. Our study additionally reveals substantial morphological variation in this species. New collections and sequences of Pleopsidium gobiense from Hami City, the type locality, are provided, from which a neotype is designated, confirming its phylogenetic position. Differences in morphology, anatomy, chemistry, and ecology among Pleopsidium species from China are discussed. A key and several phylograms are provided.

Epiphytic lichens are especially threatened by accelerated climatic change at high elevations. All lichens are sensitive to atmospheric conditions. Treelines constrain epiphyte ability to migrate upward to follow suitable conditions. Thus, acclimation to changing conditions will likely determine their survival. To simulate lichen response to climate change, we conducted a translocation field experiment in three regions of the trans‐Himalayas. Translocation of thalli to lower elevations simulated future increased temperatures, reduced relative humidity, and increased vapor pressure deficit. We hypothesized that this would decrease initial establishment, growth rates, reproduction, photosynthetic pigments, and photosynthesis, but that lichens might alternatively acclimate or shift life history strategies. The study species comprised three fruticose and six foliose species with regional medicinal or culinary uses. Dolichousnea longissima is also crucial for the endangered, endemic, lichenivorous monkey: Rhinopithecus bieti. We found some support for each hypothesis, but high interspecific, intraspecific, and regional variability. Host tree associations and bark pH impacted lichens, but microclimate variables were more important. Increased winter temperatures were most influential at the highest elevation region, whereas reduced relative humidity was most important at mid‐elevations. Increased vapor pressure deficit was beneficial to Do. longissima but detrimental to four species. Life history strategy switching occurred for both Sulcaria sulcata (beginning apothecia production in younger thalli) and Dendriscosticta hookeri (faster growth, but delayed apothecia production). The prime beneficiary of simulated climate change was Do. longissima, which had faster growth, healthier thalli, and increased photosynthetic pigments. The worst outcomes were for Hypogymnia flavida. After harvesting translocated specimens, we measured carbon exchange rates under laboratory conditions. All species increased photosynthetic rates at increased CO₂ concentrations, but temperature impacts were variable. The extent of photosynthetic acclimation varied with the degree of temperature increase. Conservation of intact mature forest habitat in high‐elevation regions will be crucial for the performance of these epiphytic lichens.

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 lichen genus Solorina exhibits significant morphological and chemical variations between species. Recent molecular studies have demonstrated that Solorina is polyphyletic, underscoring the need for a comprehensive taxonomic revision. Phylogenetic analyses employing Bayesian methods and Maximum Likelihood approaches based on three molecular loci (nrITS, nrLSU, mtSSU) revealed that species of Solorina segregate into two distinct clades. The first clade includes species characterized by bright orange lower surfaces that contain secondary metabolites, notably solorinic acid. The type species, Solorina crocea, is retained in the genus Solorina. The second clade encompasses species with white or brownish lower surfaces; most species lack secondary metabolites and are now classified as a new genus, Pseudosolorina. As a result of this taxonomic revision, two species: S. crocea and S. crocoides remain in the genus Solorina. Five species with white or brownish lower surfaces were transferred to the new genus Pseudosolorina, which consists of three newly described species and five new combinations. Four species previously described as Solorina: S. embolina, S. fuegiensis, S. octospora, and S. platycarpa have morphology consistent with Pseudosolorina, but are currently retained in Solorina due to the absence of supporting DNA sequence data. A key to Solorina and Pseudosolorina is provided. The spores of S. crocea exhibit wall ornamentation featuring rounded papillae, which are distinct from those of Pseudosolorina. Molecular data and morphological characters also indicate that both Solorina and Pseudosolorina engage in symbiotic associations with photobionts cyanobacteria Nostoc and chlorophytes Coccomyxa or Asterochloris.

Trans-Himalayan winters are projected to become milder, with shifting precipitation patterns and freeze-thaw cycles; changing stressors for their lichen communities. Lichens from Antarctica and high latitudes are cryoresistant when dry, but susceptible to cell damage if frozen when wet, or subjected to repeated freeze-thaw events. Little is known regarding cryoresistance in high-elevation, mid-latitude lichens. We collected thalli of nine species of epiphytic lichenized fungi, from three regions of the trans-Himalayas; at ≈ 4000 m, 3400 m and 2400 m elevation. We subjected thalli to differing freezing (continuous − 18 °C and − 36 °C or freeze-thaw cycles in natural daylight) and moisture conditions. Even dry thalli suffered some damage. Frozen wet thalli had greater chlorophyll degradation and reduced chlorophyll content. There were no clear elevational trends in freeze-thaw susceptibility: it caused more damage than continuous freezing. The most freeze-thaw resilient lichens were Dolichousnea longissima (from 4000 m) and Usnea florida (from 2400 m). However, species from coldest sites were most resilient to extreme freezing. Under predicted climate change conditions these sites would experience fewer annual freeze-thaw cycles, annual sub-zero days and frost days. Reduced freezing constraints might allow range expansion of mid-elevation lichens, but increase competitive pressures and temperature stressors impacting high-elevation lichens.

Kirschsteiniothelia is a saprotrophic genus that occurs in both terrestrial and aquatic habitats. This study introduces a novel species of Kirschsteiniothelia, discovered on the bark of Abies fabri, collected from Yunnan Province, China, and named K. laojunensis. The identification was established through a combination of molecular analyses and morphological characteristics. Kirschsteiniothelia laojunensis is characterized by its large subglobose to globose, black perithecia, clavate, 8-spored asci, fusiform asymmetric ascospores, which are hyaline when immature and become greenish to brown at maturity. This discovery marks the first occurrence of Kirschsteiniothelia on tree bark, with some lichen thallus tissue surrounding the base of the perithecia. Detailed morpho-molecular characterization along with a synopsis table for the genus are provided.

The lichenicolous species Sclerococcum glaucomarioides growing on the lichen Ochrolechia akagiensis is newly reported from China. This study provides an illustration and morphological description for this species, complemented by phylogenetic analyses based on ITS, LSU and mtSSU sequence data. The taxon is characterized by adpressed to sessile apothecia that are round to angular with black disc, hymenium with brownish color, 25–40 μm high, broadly cylindrical to subclavate 8-spored asci, 20–30 × 10–15 μm, with euamyloid apical cap and brown ascospores with 2–3 transverse septa.

Glypholecia qinghaiensis An C. Yin, Q. Y. Zhong & Li S. Wang is described as new to science. It is characterized by its squamulose thallus, compound apothecia, ellipsoid ascospores, and the presence of rhizines on the lower surface of the thallus. A phylogenetic tree of Glypholecia species was constructed based on nrITS and mtSSU sequences. Two species G. qinghaiensis and G. scabra are confirmed in China.