Antarctic terrestrial ecosystems, covering less than 1% of the continent, are under increasing anthropogenic threats, particularly from climate change and tourism. This study focuses on the impact of human trampling on soil microbial communities in Barrientos Island (South Shetlands archipelago), a frequently visited location. Soil samples were collected within and at the edge of two established paths representing varying levels of human disturbance. Physical and chemical analyses revealed significant differences between the paths, potentially creating anaerobic conditions favorable for specific microbial taxa. Thus, microbial communities also differed between the paths. Aerobic heterotrophic taxa were dominant in the less disturbed path, while anaerobic taxa such as Bacteroidetes vadinHA17 thrived in the more compacted path. Although alpha diversity indices did not differ, beta diversity analyses showed notable distinctions, particularly between the paths rather than trampled and untrampled areas. These findings suggest that microbial communities may recover following the stop of human activity, but also that indigenous microbial communities or other overlooked factors may be influencing the recovery potential. This study thus offers a starting point for similar research, as it highlights the need for further investigation to determine whether human trampling or other environmental factors are primarily responsible for these differences.

An increasing number of studies are describing the diversity of lichen phycobionts, which is leading to a better understanding of how lichen communities are assembled at different taxonomic, evolutionary and geographical scales. The present study explores the identity and genetic diversity of the microalgal partners of Punctelia borreri and P. subrudecta, two tropical and temperate parmelioid lichen fungi that often grow in temperate and Mediterranean forest ecosystems in Europe. Based on a specimen sampling distributed in two climatically divergent regions in the Iberian Peninsula, we found that these mycobionts are associated with Trebouxia gelatinosa, whose identity was also confirmed by an ultrastructural study of the pyrenoid. The bipartite network analysis indicated that each Punctelia species was associated with a different set of low frequency T. gelatinosa infraspecific lineages, whereas the two most abundant phycobiont lineages were shared between both mycobionts. Based on the current sampling, these two algal lineages occur exclusively in one of the two studied regions, which might point towards climate-driven, fine-tuned fungal-algal interactions. Finally, we documented visible symptoms of injury on the thalli in areas likely to have been impacted by air pollution.

Fungi are probably the most diverse group of eukaryotic organisms in the Antarctic continent and nearby archipelagos, and they dominate communities in either mild or harsh habitats. However, our knowledge of their global distribution ranges and the temporal origins of their Antarctic populations is rather limited or almost absent, especially for species that do not lichenize. We focused for the first time on elucidating the taxonomic identity and phylogenetic relationships of several Antarctic collections of the deadly fungal Basidiomycota genus Galerina. By using molecular sequence data from the universal fungal barcode and a dataset encompassing 178 specimens, the inferred phylogeny showed that the Antarctic specimens corresponded with the sub-cosmopolitan species Galerina marginata, Galerina badipes and Galerina fallax, and their most closely related intraspecific genetic lineages were from northern Europe and North America. We found that these species probably host Antarctic-endemic intraspecific lineages. Furthermore, our dating analyses indicated that their Antarctic populations originated in the Pleistocene, a temporal frame that agrees with that proposed for the Antarctic colonization of plants such as the grass Deschampsia antarctica, mosses and some amphitropical lichens. Altogether, these findings converge on the same temporal scenario for the assembly of the most conspicuous terrestrial Antarctic plant and fungal communities.

The new genus of lichenicolous fungi Austrostigmidium is described from Antarctica and Tierra del Fuego (Chile). It is characterized by the presence of black pseudothecia, pseudoparaphyses, fissitunicate, I−, KI− asci and 3-septate hyaline ascospores. So far, the only known species grows on Mastodia tessellata (Verrucariales, Eurotiomycetes). The new genus is compared with anatomically close genera. Based on nuLSU and nuSSU markers we inferred its phylogenetic relationships and found that it belongs to the family Teratosphaeriaceae (Capnodiales, Dothideomycetes) and is closely related to rock-inhabiting fungal species, as well as to the hyphomycetous lichenicolous fungus Xanthoriicola. Finally, the host-parasite interface has been analyzed by means of transmission electron microscopy and fluorescence microscopy in order to describe the interactions among the new fungus and the symbionts forming the host lichen.

For a long time, agriculture and recurrent fires have been the main factors promoting diversity changes in Mediterranean areas. We examined the effect of irrigated and non-irrigated crops and fires on the epiphytic lichen diversity of holm oak trees in the Vall d'Albaida region (Valencia, Spain). Lichen diversity was studied by calculating the LDV (Lichen Diversity Value) and the proportion of functional groups. No significant differences were observed between areas located near irrigated or non-irrigated crops. Fire-affected areas tended to harbour lower LDV and species richness than those influenced by agriculture. By using lichen functional groups, it has been shown that eutrophication tolerance, substratum pH affinity and, to some extent, thallus growth form are the main factors driving epiphytic lichen diversity in this rural area.

Based on a combined three locus analysis two new genera, Charcotiana and Amundsenia, are proposed in the lichen family Teloschistaceae, subfamily Xanthorioideae. Charcotiana includes the new species C. antarctica, which is known only from continental Antarctica. The bipolar genus Amundsenia includes the new species A. austrocontinentalis, which is also known only from continental Antarctica, and the Arctic species Caloplaca approximata which is here combined into the new genus. The two new genera are phylogenetically distinct, but poor in morphological characters; the new species consist mainly of minute apothecia in cracks of rocks located in the climatically harshest regions of the Antarctic. They are somewhat similar to another continental Antarctic species, Austroplaca frigida, which is described as a new name based on the illegitimate name Caloplaca frigida Søchting. The distribution of the four species is mapped.