Two foliose lichens as microfungal ecological niches

Abstract

The assemblage of filamentous fungi obtained from two foliose lichens, Parmelia taractica and Peltigera praetextata, collected at the same site in a coniferous forest (Aosta Valley, Italy), was studied. Ten apparently healthy thalli of each species were subjected to four isolation techniques. A total of 117 fungal taxa (67 identified to genus or species) were obtained. Numbers of fungal taxa, numbers of isolates, and diversity indices were significantly different in the two lichens; some fungal taxa were significantly associated with only one species. Multivariate analyses (cluster analysis and principal component analysis) showed a tendency towards grouping of fungal assemblages belonging to the same lichen species. These results indicate that some host specificity exists for the fungal colonizers. The range of isolated fungi included typical colonizers of leaves and the rhizoplane-ectomycorrhizoplane, microhabitats that show some ecological and structural similarities with lichen thalli. Other taxa could be obligately lichenicolous, or even true mycobionts. It is suggested that the inherent selectivity of isolation techniques may lead to underestimation of fungal populations associated in nature with Pa. taractica and Pe. praetextata.