Introduction: The inventory of fungi and myxomycetes on Cocos Island is a relatively recent process. The first record of fungi was published by Cooke & Bonar (1961), followed by the listings of Fosberg & Klawe (1966), Gómez (1983), and the contributions of Mata (2003) and Mata, Halling, & Mueller (2003). Subsequent to these studies on fungi, Rojas & Stevenson (2008) carried out research on the diversity, ecology and distribution of myxomycetes. Objective: To present a compilation and taxonomic update of the inventory of fungi and myxomycetes that were registered on Cocos Island and to facilitate the knowledge about their diversity on the island. Methods: The list provided here is based on the review of available literature, databases of herbaria and on the determination of the specimens collected recently by several researchers of the Department of Natural History of the National Museum of Costa Rica. Three field trips were made to the island to collect and photograph specimens. These field trips took place between 2016 and 2017, in the months of June, November and December. The names of the species included were adjusted according to the online database Index Fungorum. Results: A total of 648 records distributed in 401 fungi (mainly macrofungi) and 247 myxomycetes were analyzed for Cocos Island. This number of records represent 185 species, of which 139 correspond to fungi and 46 to myxomycetes. The fungi registered were distributed in 85 genera, 46 families (four of them under the term “Incertae sedis”), 21 orders (two of them as “Incertae sedis”) and two divisions (Ascomycota and Basidiomycota); meanwhile, the myxomycetes were classified in 21 genera, 10 families, 5 orders and one division (Myxomycota). The family represented most in Ascomycota was Xylariaceae (8 spp.), followed by Pyronemataceae (3 spp.) and Sarcoscyphaceae (2 spp.). In Basidiomycota, the most diverse families were Omphalotaceae and Polyporaceae (both had 11 spp.), followed by Marasmiaceae (10 spp.), Agaricaceae (8 spp.), Hymenochaetaceae (8 spp.), Mycenaceae (8 spp.), Ganodermataceae (6 spp.) and Meripilaceae (6 spp.). The families with the highest number of species recorded in Myxomycota were Stemonitidaceae (14 spp.), Physaraceae (8 spp.), Trichiaceae (6 spp.), Didymiaceae (5 spp.) and Arcyriaceae (4 spp.). Thirty-four species were recorded for the first time for Cocos Island, the majority of them belonging to fungi (Ascomycota, 8 spp. and Basidiomycota, 21 spp.) and the remaining species (5) to myxomycetes. On the island, some of the species registered are relevant because of their edible or medicinal properties. Photographs of some of the fungi collected on the island are included. Conclusions: The list generated in this study is still preliminary for the fungi and myxomycetes that were registered on Cocos Island due to certain groups such as microfungi being scarcely collected.

Keywords: Ascomycota; Basidiomycota; Myxomycota; neotropics; Cocos Island; inventory.