| Marchandiobasidium | Marchandiobasidium aurantiacum - see Erythricium aurantiacum |
| Marchandiomyces | Marchandiomyces aurantiacus - see Erythricium aurantiacum |
| Marchandiomyces corallinus | |
| Melampsora | Melampsora euphorbiae |
| Melampsora hypericorum | |
| Melampsora laricis-tremulae | |
| Melampsora rostrupii | |
| Melampsoridium | Melampsoridium betulinum |
| Melanotaenium | Melanotaenium cingens |
| Microbotryum | Microbotryum bistortarum |
| Microbotryum coronariae | |
| Microbotryum silenes-dioicae | |
| Microstroma | Microstroma album |