The pale yellowish tint of usnic acid in a lichen thallus itself is a commonly used character in identification keys, particularly in the genus Cladonia. Furthermore, the presence of usnic acid is phylogenetically significant in numerous groups of lichens. While the distinctive colour of usnic acid is readily visible when present in high concentrations, it is commonly problematic to discern when in low to moderate concentrations. We explored the use of an anisaldehyde reagent for visualizing usnic acid. Using both usnic acid-containing Cladonia samples and pure usnic acid, this reaction quickly yields a bright magenta colour on HPTLC and TLC plates after heating and directly with crude acetone extracts on glass slides heated with a lighter. The same magenta product was observed whether or not the usnic acid was accompanied by barbatic, fumarprotocetraric, psoromic, squamatic or thamnolic acids, each of which alone did not produce any colour with anisaldehyde reagent. However, the merochlorophaeic acids in C. albonigra also produced a red reaction. Analysis by high resolution LC-MS of the reaction mixture between anisaldehyde and usnic acid revealed several ions at m/z 477.1586 ([M+H]+, C27H25O8) and 463.1385 ([M+H]+, C26H23O8), respectively, consistent with aldol condensation of usnic acid and p-anisaldehyde.

The lichen species Cladonia angustiloba is characterized by a well-developed primary thallus and narrow squamules which show deep incisions, and the presence of usnic and fumarprotocetraric acids. Morphologically it is similar to C. foliacea and C. convoluta, from which it can be distiguished by the squamule size and morphology. Since similar characters were used to distinguish C. foliacea from C. convoluta which do not represent different lineages, it is necessary to examine the taxonomic status of C. angustiloba by means of DNA sequences. In this study, the species delimitation within the C. foliacea complex was studied by sequencing three loci, ITS rDNA, cox1 and RPB2. The data were analyzed by means of phylogenetic and species delimitation methods (GMYC, PTP, ABGD and BPP). Our results show that none of the three species is monophyletic. Most of the species delimitation methods did not support the current species as evolutionary lineages. Only some of the BPP analyses supported C. angustiloba as a species distinct from C. foliacea and C. convoluta. However, the hypothesis that considers the C. foliacea complex as constituted by a unique species obtained the best Bayes Factor value. Therefore, C. angustiloba and C. convoluta are synonymized with C. foliacea. A new, thoroughly checked synonymy with typifications of the whole C. foliacea complex is presented. An updated survey of the world distribution data is compiled.

To date, many studies surveying the bacterial communities in lichen thalli from diverse geographical areas have shown that Alphaproteobacteria is the predominant bacterial class in most lichens. In this study, bacterial communities in several Antarctic lichens with different growth form and substrates were analysed. The bacterial community composition in fruticose and foliose lichens, Cladonia, Umbilicaria and Usnea, and crustose lichens, Buelia granulosa, Amandinea coniops and Ochrolechia parella, from King George Island was analysed by pyrosequencing of bacterial 16S rRNA genes. Results showed that Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were predominant phyla. The predominant bacterial class in most of the samples was Alphaproteobacteria. Acetobacteriaceae of the order Rhodospiralles in Alphaproteobacteria was the most abundant bacterial family in Antarctic lichens. The LAR1 lineage of the order Rhizobiales, a putative N-fixer which has been frequently observed in lichens from temperate areas, was detected only from a few samples at low frequency. It is expected that other bacterial taxa are working as N-fixers in Antarctic lichens. From the PCoA analysis of the Fast UniFrac distance matrix, it was proposed that the microbial community structures in Antarctic lichens were affected by host species, growth form and substrates.

The new conidial lichenicolous fungus Calongia gibelluloides gen. sp. nov. is described from discoloured soredial patches on thalli of Flavoparmelia caperata and discoloured squamules of a Cladonia species collected in northern Spain. It is especially unusual in its minute size, the solitary conidiophores reaching at most 45 μm and bearing a cluster of conidiogenous cells that are at first enclosed by a membranous sheath, and produce 1-septate narrowly ellipsoid to elongate-reniform or elongate-soleiform fuscous conidia. The fungus has some features that recall the entomogenous hypocrealean genus Gibellula, but species of that genus have synnematous conidiomata, ornamented conidiophores, phialidic conidiogenous cells, no membranous vesicle, and non-septate conidia produced in chains. The phylogenetic placement remains uncertain in the absence of a teleomorph or molecular evidence.

During a study on population genetics of three species of Cladonia using the nuclear ribosomal 18S DNA, two species contained group I intron-like sequences located in positions 788 and 940 with reference to the E. coli 16S rDNA gene. The intron in position 940 was not typical of group I introns and had previously been described only from the Parmeliaceae and Lecanoraceae, but here we report the occurrence of this intron in the Cladoniaceae. The intron in position 788 had characteristics of group I introns and had previously been reported from the Physciaceae. In this paper we provide for the first time a putative RNA fold for the nS788 intron, compare the secondary RNA structure of the Cladonia group I introns (nS788 and nS940) to that of other taxa, and infer a phylogenetic history among 15 members of the Lecanorales based on the evolutionary history of the nS788 group I intron. The RNA fold for nS788 contained two optional hairpins, P2.1 and a potentially newly described hairpin referred to as P5.1. The phylogenetic hypothesis supports the monophyly of the genus Cladonia. It also supports the separation of two large groups in the Physciaceae; the Buellia-group and the Physcia-group.

A new species Opegrapha cladoniicola, lichenicolous on the podetia of Cladonia ochrochlora, is described from Hawaii. It is the first known Opegrapha species found growing on Cladonia.

The new lichen species Cladonia krogiana is described from eight localities in SE Norway. It resembles C. polycarpoides morphologically, but differs in containing barbaric acid and chlorovinetorin.