Sphaerellothecium reticulatum (Zopf) Etayo, a new lichenicolous fungus for Antarctica

In the project aiming to determine the lichen mycota of James Ross Island, we identifieda new lichenicolous fungus species which is reported from Antarctica for the first time:Sphaerellothecium reticulatum on Flavoparmelia gerlachei. Although this species wasidentified on other parmelioid lichens, it was never reported on Flavoparmelia spp.&nbsp;</p

Identification of some lichenised fungi from James Ross Island (Antarctic Peninsula) using nrITS markers

James Ross Island (Antarctic Peninsula) is one of the lichen rich islands of Antarctica because of its large deglaciated area, with over 140 species of lichenised fungi being reported from the island. Because of its rich lichen biodiversity we decided to study the lichen biodiversity of James Ross Island in more detail, using molecular techniques in addition to morphological characters. Collections made from James Ross Island in the 2016-2017 season by the first and second authors showed that lichen biodiversity of Antarctica is still poorly known and that molecular studies should be carried out to determine the lichen mycota of the white continent. For this research we selected five species and, after morphological and anatomical studies, we also worked with the nrITS gene regions of the selected specimens. Aspicilia virginea and Peltigera ponojensis are new to Antarctica and we provide nrITS data for Candelaria murrayi and Flavoparmelia gerlachei for the first time. Austroplaca frigida was only known from continental Antarctica and we report this species from maritime Antarctica for the first time. Detailed descriptions, habitat preferences and nrITS phylogenies of these species are provided. We believe that the lichen biodiversity of Antarctica will be much better known if molecular techniques are used in the classification of lichenised fungi

New records of lichenized fungi for Antarctica

Three lichenized fungal species collected from James Ross Island (eastern coast of Antarctic Peninsula): Cladonia acuminata (Ach.) Norrl., Rhizocarpon pusillum Runemark and Rhizoplaca parilis S.D. Leav., Fern.-Mend., Lumbsch, Sohrabi et St. Clair are reported from Antarctica for the first time. Detailed morphological and anatomical properties of these species along with photographes based on Antarctic specimens are provided here. In addition, the nrITS gene regions of the selected specimens are studied and the phylogenetic positions of the species are discussed. The nrITS data for Rhizocarpon pusillum is provided for the first time. According to our studies the lichen biodiversity of the Antarctic is still poorly known and molecular studies are very important in order to present the correct lichen biodiversity of Antarctica

Inhibition of Primary Photosynthesis in Desiccating Antarctic Lichens Differing in Their Photobionts, Thallus Morphology, and Spectral Properties

Five macrolichens of different thallus morphology from Antarctica (King George Island) were used for this ecophysiological study. The effect of thallus desiccation on primary photosynthetic processes was examined. We investigated the lichens' responses to the relative water content (RWC) in their thalli during the transition from a wet (RWC of 100%) to a dry state (RWC of 0%). The slow Kautsky kinetics of chlorophyll fluorescence (ChlF) that was recorded during controlled dehydration (RWC decreased from 100 to 0%) and supplemented with a quenching analysis revealed a polyphasic species-specific response of variable fluorescence. The changes in ChlF at a steady state (Fs), potential and effective quantum yields of photosystem II (F-V/F-M, phi(PSII)), and nonphotochemical quenching (NPQ) reflected a desiccation-induced inhibition of the photosynthetic processes. The dehydration-dependent fall in F-V/F-M and phi(PSII) was species-specific, starting at an RWC range of 22-32%. The critical RWC for phi(PSII) was below 5%. The changes indicated the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts at RWCs of below 20%. In both the wet and dry states, the spectral reflectance curves (SRC) (wavelength 400-800 nm) and indices (NDVI, PRI) of the studied lichen species were measured. Black Himantormia lugubris showed no difference in the SRCs between wet and dry state. Other lichens showed a higher reflectance in the dry state compared to the wet state. The lichen morphology and anatomy data, together with the ChlF and spectral reflectance data, are discussed in relation to its potential for ecophysiological studies in Antarctic lichens

Antarctic Lichens under Long-Term Passive Warming: Species-Specific Photochemical Responses to Desiccation and Heat Shock Treatments

Climate warming in the Antarctic tundra will affect locally dominant cryptogams. Being adapted to low temperatures and freezing, little is known about the response of the polar lichens' primary photochemistry to warming and desiccation. Since 2008, we have monitored the ecophysiological responses of lichens to the future warming scenario during a long-term warming experiment through open top chambers (OTCs) on Fildes Peninsula. We studied the primary photochemical response (potential Fv/Fm and effective efficiency of photosystem II YPSII) of different lichen taxa and morphotypes under desiccation kinetics and heat shock experiments. As lichens grow slowly, to observe changes during warming we methodologically focused on carbon and nitrogen content as well as on the stable isotope ratios. Endemic Himantormia lugubris showed the strongest effect of long-term warming on primary photochemistry, where PSII activity occurred at a lower %RWC inside the OTCs, in addition to higher Fv/Fm values at 30 degrees C in the heat shock kinetic treatment. In contrast, Usnea aurantiaco-atra did not show any effect of long-term warming but was active at a thallus RWC lower than 10%. Both Cladonia species were most affected by water stress, with Cladonia aff. gracilis showing no significant differences in primary photochemical responses between the warming and the control but a high sensibility to water deficiency, where, at 60% thallus RWC, the photochemical parameters began to decrease. We detected species-specific responses not only to long-term warming, but also to desiccation. On the other hand, the carbon content did not vary significantly among the species or because of the passive warming treatment. Similarly, the nitrogen content showed non-significant variation; however, the C/N ratio was affected, with the strongest C/N decrease in Cladonia borealis. Our results suggest that Antarctic lichens can tolerate warming and high temperature better than desiccation and that climate change may affect these species if it is associated with a decrease in water availability