Fungal genera: Icmadophila [13 taxa], Idiocercus [9 taxa], Idiomyces [1 taxon], Idriella [127 taxa], Ijuhya [7 taxa], Illosporium [19 taxa], Imimyces [2 taxa], Immotthia [3 taxa], Incrucipilum [5 taxa], Incrupila [6 taxa], Indiella [1 taxon], Inesiosporium [3 taxa], Inflatostereum [1 taxon], Infundibura [1 taxon], Ingoldiella [7 taxa], Inifatiella [5 taxa], Inocutis [3 taxa], Inocybe [178 taxa], Inocyclus [2 taxa], Inonotus [621 taxa], Inopilus [4 taxa], Insecticola [2 taxa], Intercalarispora [25 taxa], Iodophanus [316 taxa], Iodosphaeria [1 taxon], Ionomidotis [9 taxa], Ionophragmium [1 taxon], Irene [30 taxa], Irenina [3 taxa], Irenopsis [1058 taxa], Irpex [190 taxa], Irpiciporus [5 taxa], Irpicodon [7 taxa], Isaria [82 taxa], Isariopsis [44 taxa], Ischnoderma [49 taxa], Isia [2 taxa], Isipinga [20 taxa], Isoachlya [4 taxa], Isothea [7 taxa], Isthmiella [122 taxa], Isthmolongispora [10 taxa], Isthmophragmospora [1 taxon], Isthmospora [9 taxa], Isthmotricladia [7 taxa], Itajahya [9 taxa], Itersonilia [1 taxon], Ithyphallus [5 taxa], Iwilsoniella [1 taxon], Iyengarina [3 taxa]