Diversity and distribution of Lichen taxa in Argentina

Lichens are symbiotic associations where a fungus forms a partnership with one or more photosynthetic organisms, like algae or cyanobacteria. They are capable of thriving in a wide range of environments, from desert regions to tropical forests, aquatic ecosystems to mountainous areas, and can grow on rocks, trunks, leaves, soil, and anthropogenic substrates. The aim of this study is to determine the lichen richens in Argentina and their diversity across each province. This study provides an updated assessment of lichen diversity and distribution in Argentina, documenting 1,864 taxa (species and infraspecific taxa), representing a 16% increase since the last catalog. Southern regions (Tierra del Fuego, Islas del Atlántico Sur, Río Negro) showed the highest richness, while northern and central-western region exhibited lower diversity, partly due to historical sampling biases. Three indices (taxonomic biodiversity, ecoregionbased diversity, and aridity-adjusted diversity) revealed that lichen distribution is shaped by climate, substrate availability, and uneven research effort rather than strict latitudinal gradients. The findings underscore the need for targeted fieldwork in underrepresented regions (arid northwest), molecular taxonomic revisions, and collaborative efforts to address knowledge gaps.