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.

Five species of Umbilicaria are described, three of which, U. africana, U. krascheninnikovii and U. nylanderiana, have not been previously recorded from Antarctica. Distributional patterns and morphological characteristics of these species are discussed.

The Antarctic endemics Umbilicariakappenii and U. antarctica are morphologically close, but mainly distinguished by their reproductive strategies. Umbilicaria antarctica propagates by means of thalloconidia. Umbilicaria kappenii lacks thalloconidia, but exhibits a variety of asexual propagules: soredia, adventive lobes and thallyles. We have now employed molecular data from three gene regions to examine the phylogenetic relationships of these two morphotypes. The phylogeny of ten samples and four outgroup taxa (Umbilicaria decussata, U. krascheninnikovii, U. nylanderiana, U. umbilicarioides) was reconstructed using Bayesian and maximum parsimony analyses of a combined data set of nuclear ITS, nuclear LSU rDNA and mitochondrial LSU rDNA sequences. Forty two new partial sequences of 14 specimens were generated. Our results indicate that all samples morphologically referred to U. antarctica and U. kappenii form a monophyletic group. A topology separating the two morphotypes as phylogenetic species is significantly rejected with the data set. It is proposed to place U. kappenii into synonymy with U. antarctica.