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There is a long history of studies on lichens found in ultramafic habitats, but comparisons between lichen communities on different ultramafic lithologies are scant, and potential metabolic adaptations to the multiple edaphic stresses of ultramafic substrates have been widely neglected. The present work is the first to characterise differences in the abundance and structure of saxicolous lichen communities on different ultramafic lithologies (dunite, lherzolite, and serpentinite), analysed in two areas of the Western Alps (NW Italy). Differences between communities on various ultramafic lithologies were observed, including differences between a mafic control (Mg-Al metagabbro); however, factors other than the substrate were observed to drive more remarkable differences between lichen communities on ultramafics of alpine and pre-alpine areas. XRF analyses demonstrated that the mineral composition of different lithologies is reflected by metal contents in crustose lichens, with weathering processes accounting for relative shifts in elemental abundances between rocks and thalli. A thin layer cromatography screening of lichen secondary metabolites (LSMs), which are thought to regulate metal and pH homeostasis in thalli, revealed lithological vicariance among dominant lichen species with different LSM patterns and intraspecific variability in LSM production associated with differences in lithology and location. In particular, the presence or absence of norstictic acid in species or lineages/individuals on the different lithologies, in relationship to concentrations of Fe, Mg, and Ni in lichen thalli, was recognised as a metabolic adaptation to metal stress. Pull-up tests revealed that physical factors such as a differential surface disaggregation may contribute more towards differences observed in lichen abundance on the different lithologies investigated.

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4 Laboratorio analisi scientifica, Direzione ricerca e progetti cofinanziati, Soprintendenza per i beni e le attività culturali, Regione Autonoma Valle d'Aosta -Piazza Narbonne 3, 11100, Aosta, Italy AbstractRelationships between reproductive strategies and population spatial structure have been often suggested for lichens, but still not supported with experimental aerobiological data. For the first time, this study couples aerobiological investigations on meiospore dispersal by Caloplaca crenulatella (Nyl.) H. Olivier and Rhizocarpon geographicum (L.) DC. with the analysis of their local spatial patterns on the walls of a medieval castle in NW-Italy. During a two-year monitoring period carried out in the castle courtyard, a total of 169 polar diblastic spores, 20% of which were morphologically attributable to C. crenulatella, was detected in the mycoareosol, while muriform spores of R. geographicum were never found. Laboratory experiments confirmed that different dispersal patterns characterize the two species, the meiospores of R. geographicum being poorly discharged and only recovered at a short distance from the thalli, whereas those of C. crenulatella were more abundantly discharged, suspended and better dispersed by a moderate air flow. Such a difference was reflected on the castle walls by a random spatial pattern of C. crenulatella, while R. geographicum showed a clustered distribution. Different discharge rates and take-off limitations, possibly related to size differences between the spores, are not sufficient to explain the different colonization patterns and dynamics of the two species, and additional intrinsic and extrinsic factors likely drive the dispersal and establishment success. Nevertheless, information on the relationships between different dispersal patterns of the species and the local spatial structure of their populations may contribute to predict the recovery potential of lichen species exposed to habitat loss or disturbance, or encrusting monumental surfaces. Events of long-distance dispersal, favouring colonization of distant sites, followed by shortdistance dispersal, supporting a more local population expansion, were shown to explain the patchy lichen colonization in a former tree-less landscape (Gjerde et al. 2015). The productions of large asexual diaspores (isidia, soredia) and small sexually-generated meiospores are traditionally related to local and long distance dispersal, respectively (Hedenås et al. 2003;Leavitt & Lumbsch 2016). At the landscape scale, inferences from genetic population studies and spatial pattern analyses mostly supported this view, suggesting a tradeoff between a higher dispersal of meiospores, effective in landscapes with lower connectivity, and a higher establishment effectiveness of asexual diaspores in continuous landscapes (Ellis 2012). In-field measurements on diaspore dispersal generally showed short dispersal capabilities, but evidence on distributional ranges and phylogenetic studies suggested they are (2012) found a spatially structured pattern...

In this contribution, new data concerning lichens and bryophytes of the Italian flora are presented. It includes new records, exclusions, and confirmations to the Italian administrative regions for taxa in the lichen genera Athallia, Ramonia, Thelotrema, Pertusaria, Bryoplaca and in the bryophyte genera Dicranella, Bryum, and Scorpiurium.