Lichens, colorful plant-like beings that commonly grow on rock, bark, and other surfaces, are perceived as individual organisms, but in fact comprise a symbiotic system, consisting of a fungal and an algal component. The lichen symbiosis is thus a particular nutritional association, just as mushrooms form underground root connections, called mycorrhizas, with trees, but lichens are much more complex in biological features. Most lichenized fungi belong to the Ascomycota, a large group that includes many economically important species. New scientific evidence shows that the lichenized life style significantly contributed to the evolution and diversification of Ascomycota. Some 15,000 species are currently accepted, but comparatively little is known about tropical lichens, which are considered key elements in the evolution of lichenized Ascomycota. TICOLICHEN is a major tropical lichen biodiversity inventory, forming part of the Costa Rican Sustainable Biodiversity Development Initiative, an international effort to unravel Costa Rica's organismic diversity. As a collaborative project between the Field Museum in Chicago, the National Institute of Biodiversity in Costa Rica, and the Botanical Museum in Berlin, TICOLICHEN combines well-developed local scientific infrastructure with international taxonomic expertise. Dr Robert Luecking has assembled a team of specialists, local taxonomists, and national and international students, to document the lichen flora of this biologically diverse country, suspected to comprise some 3000 species. Methods include field work to gather representative collections and measure ecologically relevant parameters, museum revisions of thousands of type specimens to clarify the names of known species and the relationships of the many new species to be expected, electronic databasing and image-based documentation, creation of publicly accessible websites, and field workshops to train students and local professionals in tropical lichen taxonomy and biology. One final outcome, a printed lichen flora of Costa Rica for species description and identification, shall endeavor to match the high standards set by floras covering temperate regions, such as the recently published Lichens of North America. The results of this project will serve as a model for lichenological survey work in other tropical countries, help to develop local scientific expertise, and greatly facilitate studies of tropical lichens beyond taxonomy and biodiversity, such as their evolution within the Ascomycota, their biogeography and ecology, their functional role in tropical ecosystems, their use as bioindicators of tropical forest degradation, land use change, and conservation, and their potential medical and industrial applications based on their rich secondary chemistry.
