Mycosphaerella is a genus of ascomycota. With more than 10,000 species, it is the largest genus of plant pathogen fungi. The following introduction about the fungal genus Mycosphaerella is copied (with permission) from the dissertation of W. Quaedvlieg (named: Re-evaluating Mycosphaerella and allied genera). * The genera Passalora and Pseudocercosporella are known to be paraphyletic and will be treated separately in the near future.