Seven Graphis species are reported as new to Europe from the Serra de Sintra and the Planalto das Cezaredas, two regions of Portugal where graphidoid Graphidaceae are abundant and diverse. The following species were identified: Graphis cincta, G. crebra, G. handelii, G. leptospora, G. lineola, G. plumierae, and G. verminosa. Many of these share two characters: a densely inspersed hymenium and the presence of norstictic acid in the thallus. A key to the Graphis species known from Europe is provided. The possible reasons for the high, previously unknown, diversity of graphidoid Graphidaceae in this region are discussed. Global warming might be a contributory factor.

The new name Neosergipea M. Cáceres, Ertz & Aptroot is introduced to replace Sergipea M. Cáceres, Ertz & Aptroot, which is a later homonym of Sergipea Regali, Uesugui & Santos, a genus of fossil pollen. Using the small subunit of the mitochondrial rDNA cistron, we present an updated phylogeny of the Enterographa clade in Roccellaceae which includes the genera Dichosporidium, Enterographa, Erythrodecton, Mazosia, and Neosergipea. While in a previous analysis the relationship between Neosergipea and Dichosporidium was unresolved, our results suggest Neosergipea to be an unsupported sister to Dichosporidium s. lat. The latter potentially represents two distinct genera, differing in ascospore type.

The present study investigates the photobiont diversity of the boreal felt lichen, Erioderma pedicellatum. Previously sampled genetic data from Newfoundland were reanalyzed and new sequence data (16S rDNA, rbcLX) of the boreal felt lichen from Alaska (USA), Kamchatka (Russia), and North Trøndelag (Norway) were generated. The highest genetic diversity of the photobiont is found in Alaska and Kamchatka, indicating that these may be the primary sources of the species in the Northern Hemisphere. In Newfoundland, the photobiont of E. pedicellatum was screened on leaves of the symbiotic liverwort Frullania asagrayana and it was found to occur on trees where no other lichens were present, demonstrating that the geographical distribution, and possibly also the ecological requirement of the photobiont of E. pedicellatum, is wider than that of the lichen phenotype. Finally, a postulated association between the occurrence of the vegetatively reproducing Coccocarpia palmicola and the occurrence of the compatible photobiont of E. pedicellatum on the same tree could not be established.

Foliicolous lichens complete their life cycles upon non-deciduous leaves in humid tropical and subtropical environments. The anatomy of these lichens and its adaptations to this specialized niche have received only limited attention. The present work examines the structural organization in seven species of the Gomphillaceae that colonize palm leaves in south-west Florida, USA. Thalli with their leaf substratum were embedded in resin and examined with SEM in backscattered electron detection mode. All species showed a continuous, covering epilayer of fungal origin that consisted of relatively sparse, scattered cell lumina of reduced diameter connected by cell wall-derived material. Fungal cells were intermixed below this layer, with algal cells often resting directly on the substratum. Interactions between symbionts were mainly limited to wall-to-wall contacts without penetration. The epilayer showed continuity with the fungal prothallus at the perimeter of the thalli. Crystalline deposits in the upper portions of thalli were common, particularly in the species of Gyalectidium examined. All thalli were entirely epicuticular; some covered the stomata of the leaf beneath. It is suggested that the prominence of non-living wall materials and mineral crystals in thallus structure might serve to minimize the metabolic cost of fungal tissue in climates where warm temperatures at night result in higher rates of respiration.

In order to improve growth chamber protocols for lichens, we tested the effect of 1) wet filter paper versus self-drained nets as a substratum for lichens, and 2) gradual versus abrupt transitions between dark and light periods. For Lobaria pulmonaria (L.) Hoffm. cultivated on nets, RGR increased by 60% compared to those on wet papers, whereas abrupt on/off transitions between day/night gave as high growth rates as gradual transitions mimicking sunrise/sunset. Because thalli on nets had less surface water than those on papers, the higher RGR on nets likely resulted from less suprasaturation depression of photosynthesis. By supporting very high growth and eliminating any visible damage, the revised growth chamber protocols facilitate new functional lichen studies.

Tyrosinases are a widespread family of multicopper oxidase enzymes. In our earlier work, we identified the presence of tyrosinases in lichenized Ascomycetes based on their substratum specificity, sensitivity to inhibitors and molecular mass. Here, we present a more detailed characterization of a tyrosinase from the lichen Lobaria pulmonaria. We also compare tyrosinase activity with the activities of laccases and peroxidases, the other redox enzymes present in this species. The importance of tyrosinases in lichen biology was studied by testing their role in melanin synthesis. Laboratory experiments clearly showed that tyrosinases from L. pulmonaria resemble those from other lichens and in free-living fungi. While the tyrosinases can metabolize the melanin precursor L-DOPA, L-DOPA can also be metabolized by peroxidases and laccases. A field experiment showed that exposing shade-adapted L. pulmonaria to normal solar radiation induces L-DOPA melanin synthesis. Synthesis occurred when lichens were exposed to either direct sunlight, or placed under a wavelength-neutral filter that slightly reduced overall light. In lichens receiving unfiltered sunlight, melanin synthesis was accompanied by increased laccase activity; by contrast, no changes in enzyme activity occurred in lichens placed under the wavelength-neutral filter. Melanization was reduced by placing lichens under filters that removed UV-B, and prevented by filters that removed both UV-A and UV-B. Removing UV-B had no effect on enzyme activity, whereas removing both UV-A and UV-B increased tyrosinase activity. Results from this study indicate that under some conditions laccases may be involved in melanin synthesis, but they provide no evidence for a role for tyrosinases in melanization. Although high tyrosinase activities are widespread in lichens, many questions on the role of this enzyme in lichen biology remain to be answered.

The composition of fatty acids (FAs) is known to discriminate families within genera of bacteria, fungi, octocorals and algae. Here, we applied the more sensitive gas chromatographic (GC) analysis to investigate the taxonomic value of using FA composition to discriminate 15 species of lichen, including three chlorolichens (two Cladonia species and Stereocaulon scutelligerum), nine tripartite lichens (Stereocaulon species) and three cyanolichens (Lichina pygmaea, Collema cristatum, Peltigera membranacea). One macroscopic cyanobacterium (Nostoc sp.), corresponding to the photobiont partner of Peltigera and Collema cyanolichens, was included for comparison. Five lipid extraction methods were evaluated, using Stereocaulon scutelligerum. Shaking at 80 °C with chloroform/methanol (2:1, v/v) was the most efficient and reproducible method. The total FA composition of the 16 species was compared, using GC coupled with flame ionization detection or mass spectrometry. A statistical hierarchical cluster analysis was used to determine the similarity between the FA profiles, based on total, saturated, unsaturated and branched-chain FAs (BCFAs). The BCFA profile allowed a distinction between the Stereocaulon species and the cyanolichens, in contrast to all the other types of FAs. A detailed characterization of eight FA subclasses, provided by the GC analysis, suggested a preferential pathway for the biogenesis of unsaturated FAs through desaturases, which was especially favoured in the cyanolichens.