Exploring the biogeography of foliicolous lichens: A focus on the family Gomphillaceae.

In tropical and subtropical environments, lichens growing on living leaves, known as "foliicolous lichens", are amongst the best-known in terms of taxonomy and distribution. Through extensive examination of herbarium collections, previous studies delineated six lichenogeographical regions. Many foliicolous morphospecies exhibited a widespread distribution, e.g., occurring in both the Neo- and the Paleotropics. Our overarching goal is to reconstruct the phylogeny and biogeography of the Gomphillaceae family, one of the dominant elements of foliicolous lichen communities in tropical rain forests. Expanding on an existing dataset from Brazil, we added: i) samples from four continents and islands in three oceans (Guadeloupe, Madagascar, New-Caledonia, Taiwan) ii) non-foliicolous taxa iii) an additional locus (RPB1), and iv) the rbcL locus from the photobiont. Our questions are: (a) What is the global biogeographical history of Gomphillaceae? (b) What is the extent of undiscovered biodiversity in the family? (c) Does the molecular diversity mirror the trend observed in morphospecies, i.e., with many widely distributed species? (d) Does the biogeographical history of the photobiont reflect that of the fungus? Based on 1300 specimens, we applied an integrative taxonomy approach, including detailed phenotypical observations, phylogenetic and species delimitation analyses (GMYC, BPP and ASAP), and ancestral area reconstruction using BioGeoBEARS. Our phylogeny comprises a total of approx. 400 species. We highlighted a high level of unknown diversity, with 53 new clades outside of described genera and approx. 100 undescribed species. Our results challenge previous beliefs, revealing more restricted distributions in phylogenetic species compared to morphospecies.