XVI International Botanical Congess

The biologically defined group of lichenicolous fungi is more or less specialized in growing on or in lichens. This is an exceptional life-style resulting in at least three-biont systems which can persist over a long period of time. The majority of these fungi are ascomycetes and mitosporic fungi but a number of basidiomycetes and few myxomycetes occur just as well. The total amount worldwide is estimated to be 2000 species. In the Sonoran region, c.150 species might occur, placed in about 50 genera. The biological spectra of selected genera are discussed. The species can show phylogenetic relationships either to saprophytic, fungicolous, algicolous or lichenized ones, but certain biological boundaries do exist. Various life strategies and parasitic, parasymbiontic and adelphosymbiontic behaviours are discussed. The ecological adaptationsof lichenicolous fungi on the long life-span of their hosts as well as on the high insolation and aridness of Sonoran habitats are shown by examples. Several taxa of the Sonoran region are depicted regarding their host-selectivity, substrate choice and geographical distribution.