Additions to the lichen biota of Isla del Coco, Puntarenas, Costa Rica.
Introduction: The floristic composition of Isla del Coco is relatively well known. While studies have been typically oriented to flowering plants, other organisms such as lichens remain understudied. Objective: The purpose of this inventory is to expand the documentation of lichen species found in Isla del Coco, by reviewing literature and herbarium collections, as well as new collections, to facilitate the understanding of the diversity of said organisms. Methods: A list of the collections deposited in several herbaria was prepared, complemented with the bibliographical references of previous works. In addition, a field trip to collect and photograph specimens was performed in November 2017. The names of the species were adapted according to the online database Index Fungorum. Results: A total of 284 specimens were studied, corresponding to 173 different taxa, including 40 new records. Twenty-five taxa were identified at the genus level and 148 at the species level. The specimens were distributed in 23 families and 66 genera. The best-represented families are Graphidaceae (37 spp.), Pilocarpaceae (34 spp.) and Collemataceae (8 spp.). Porina (17 spp.) and Strigula (14 spp.) were the most diverse genera. The majority (52%) of the 148 species have a pantropical distribution, 34% are Neotropical and 13% are cosmopolitan. Endemic (according to current knowledge) represent about 1% of the species. Conclusions: Despite the addition of new taxa to the list, this is far from reflecting the existing lichen diversity on the island, as there are still many areas to explore.