The delimitation of Antarctic and bipolar species of neuropogonoid Usnea (Ascomycota, Lecanorales): a cohesion approach of species recognition for the Usnea perpusilla complex.

Species of the Neuropogon group in the lichen genus Usnea have their centre of distribution in polar regions of the Southern Hemisphere. Their morphological and chemical variability is poorly understood and several asexual taxa with uncertain relationships to fertile taxa occur in the group. The species concept is controversial.

The sterile microfilamentous lichenized fungi Cystocoleus ebeneus and Racodium rupestre are relatives of plant pathogens and clinically important dothidealean fungi.

The phylogenetic positions of the always-sterile microfilamentous lichens Cystocoleus ebeneus and Racodium rupestre were studied in a phylogenetic framework using sequence data of 5' nuSSU, nuLSU, and mtSSU rDNA. The analysis reveals that both genera are ascomycetes and belong to Dothideomycetidae: they are not close to lichenized members within the subclass, but rather belong to Capnodiales. The macroscopically scarcely distinguishable C.

Lichen fungi have low cyanobiont selectivity in maritime Antarctica.

•  The cyanobionts of lichens and free-living Nostoc strains from Livingston Island (maritime Antarctica) were examined to determine both the cyanobiont specificity of lichens and the spatial distribution of Nostoc strains under extreme environmental conditions. •  We collected five different lichen species with cyanobacteria as primary or secondary photobiont (Massalongia carnosa, Leptogium puberulum, Psoroma cinnamomeum, Placopsis parellina and Placopsis contortuplicata) and free-living cyanobacteria from different sample sites and analysed them using the tRNA (UAA) intron as a genetic marker to identify the cyanobacterial strains. •  Our results showed that the same Nostoc strain was shared by all five lichen species and that an additional strain was present in two of the lichens.