Fungi are on the priority groups for OHBR as they have not been widely recorded in the past. The database includes records of macro-fungi (mushrooms, toadstools, brackets) and micro-fungi (mildew, moulds, rusts, smuts). Over 490 species are illustrated on the Outer Hebrides Fungi website, which includes photographs of microscopic characters but not distribution maps.

The slime moulds belong to the phylum Myxomycota, which is part of the fourth kingdom Protista. They have been included with the fungi for convenience. They are difficult to identify and we currently have very few records.

Lichens are a compound organism composed of a fungus with an alga and sometimes a cyanobacterium but are included in the same kingdom as the fungi. They are priority recording group for OHBR and a work on a systematic checklist is in progress. The lichens will be added to the OHBR Fungi website during 2020.