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Three twig-growing lichen species belonging to the family Teloschistaceae from southern Patagonia are described as new to science: Marchantiana pyramus sp. nov., with minute apothecia, orange due to dominant content of emodin, M. ramulicola sp. nov., with minute olive apothecia with dominant parietin and Austroplaca thisbe sp. nov., with clear yellow apothecia also with dominant parietin. Marchantiana subpyracea , M. epibrya and M. queenslandica are new combinations for species which, so far, are known only from New Zealand and Australia. Blastenia circumpolaris is shown to be very common in Patagonia and Marchantiana asserigena is documented for the first time from the Southern Hemisphere, viz. the Falkland Islands. The genus Marchantiana is analyzed here using three genes and is shown to be closely related to Yoshimuria ; although appearing as paraphyletic, a monophyletic origin cannot be ruled out. Morphology, ecology and distribution support a monophyletic treatment and Marchantiana is therefore treated as such. [ABSTRACT FROM AUTHOR]

Background and Aims Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understanding of lichen symbiosis because of the macroalgal nature of the photobiont, the flexibility of the symbiotic interaction and the co-existence of free-living and lichenized forms in the same microenvironment. In this context, we aimed to (1) characterize the photosynthetic performance of co-occurring populations of free-living and lichenized Prasiola and (2) assess the effect of the symbiosis on water relations in Prasiola , including its tolerance of desiccation and its survival and performance under sub-zero temperatures. Methods Photochemical responses to irradiance, desiccation and freezing temperature and pressure–volume curves of co-existing free-living and lichenized Prasiola thalli were measured in situ in Livingston Island (Maritime Antarctica). Analyses of photosynthetic pigment, glass transition and ice nucleation temperatures, surface hydrophobicity extent and molecular analyses were conducted in the laboratory. Key Results Free-living and lichenized forms of Prasiola were identified as two different species: P. crispa and Prasiola sp. respectively. While lichenization appears to have no effect on the photochemical performance of the alga or its tolerance of desiccation (in the short term), the symbiotic lifestyle involves (1) changes in water relations, (2) a considerable decrease in the net carbon balance and (3) enhanced freezing tolerance. Conclusions Our results support improved tolerance of sub-zero temperature as the main benefit of lichenization for the photobiont, but highlight that lichenization represents a delicate equilibrium between a mutualistic and a less reciprocal relationship. In a warmer climate scenario, the spread of the free-living Prasiola to the detriment of the lichen form would be likely, with unknown consequences for Maritime Antarctic ecosystems. [ABSTRACT FROM AUTHOR]

Botany Bay is one of the richest sites for lichen and bryophyte biodiversity in continental Antarctica. A total of 29 lichen, nine moss and one liverwort species have been identified. The most extensive vegetation occurs on a sheltered raised beach terrace. Vegetation associations are described and compared to other continental Antarctic localities that also possess a rich vegetation cover. Ordination analysis clearly indicates the importance of the type of water supply, its regularity, the substrate type, and particularly in Botany Bay, the influence of nutrients derived from the local bird population in governing plant distribution and associations. A vegetation map has been produced and can be used as a baseline to assess vegetation changes over time. [ABSTRACT FROM AUTHOR]