Präadaption bei Flechten iranischer Halbwüsten

Abstract

25 species of lichens have been collected in semidesertic to desertic areas of Iran. On the basis of spatial relations to the substrate and anatomical features of the thallus three main groups (one with a subdivision based on colour and morphology of the thallus) can be differentiated. Selective advantages and peculiarities in connection with the desert habitat are pointed out, such as inverse thallus-structure, a dense network of skeletal hyphae in the substrate in otherwise epilithic species, proliferating areolae of the thallus, immersed pycnidia with trichogynes and brownish spores in groups with usually colourless spores. Most of the species are wide-spread in arid and often also in humid regions; only one species,Verrucaria buschirensis J. Steiner, seems to be endemic. The prevalence of cyanophilic lichens in deserts may have phylogenetic reasons, as these groups appear to date back to periods without higher vegetation and a desert-like environment.