Abstract
An overview over the present state of investigations on foliicolous lichens in the Neotropics is provided. Historically, a division can be made into (1) the initial period, dominated by the work of J. Müller Argoviensis, (2) the monography of R. Santesson, (3) the Brazilian phase, characterized by the Brazilian mycologist A. C. Batista and his working group, and (4) the modern period, with detailed monographical and floristical studies and an increasing interest in the ecology of foliicolous lichens and their use as bioindicators. We now have rather good knowledge of the taxonomy and systematics of most groups, although new species are continuously described and some families and genera are in need of revision. Detailed floristical information is available from a few regions only, and biogeographical data are therefore incomplete and controversial. Modern ecological studies have been made to some extent, yet the results and their implications have to be verified by extended studies inside and outside the Neotropics. Preliminary data indicate that foliicolous lichens are useful as bioindicators in various respects. Biogeographically, the Neotropics are characterized by a high number of exclusive species and by their affinity with tropical Africa. Within the Neotropics, biogeographical subdivisions, as established by higher plant distribution patterns, are only in a few instances supported by the distribution of foliicolous lichens. In general, subtile biogeographical conclusions with respect to foliicolous lichens are difficult, because of the wide distribution of many species and the insufficient floristic knowledge of particular regions.