The genus Mycosphaerella in the broad sense comprises one of the largest genera in the phylum Ascomycota where it has evolved over a broad developmental and physiological adaptationrange which includes endophytes, saprophytes and symbionts. Together with its more than 30 anamorph genera, the most noteworthy of these including Septoria, Cercospora, Pseudocercospora, Ramularia, Dothistroma etc, it contains more than 10,000 species names. For the major part Mycosphaerella consists of narrow host range, follicolous plant pathogens that are the cause of significant economical losses in both temperate and tropical crops worldwide; however, it is not uncommon to also encounter species with a broad host range.  Although originally thought to be monophyletic, in recent years Mycosphaerella was shown to be polyphyletic and teleomorph genera such as Davidiella (with Cladosporium anamorphs) and Teratosphaeria (frequently with Readeriella and Kirramyces anamorphs) were split off the genus. The recent advance in molecular techniques and the continuous effort to obtain living cultures of previously described species, have made it finally possible to start resolving the Mycosphaerella generic complex into clearly defined species and genera.

References

    Crous PW, Kang J-C, Braun U. 2001. A phylogenetic redefinition of anamorph genera in Mycosphaerella based on ITS rDNA sequence and morphology. Mycologia 93: 1081-1101.
    Crous PW, Braun U, Schubert K, Groenewald JZ. 2007. Delimiting Cladosporium from morphologically similar genera. Studies in Mycology 58: 33-56.
    Crous PW, Summerell BA, Carnegie AJ, Wingfield MJ, Hunter GC, Burgess TI, Andjic V, Barber PA, Groenewald JZ (2009). UnravellingMycosphaerella: do you believe in genera? Persoonia 23: 99-118.
    Crous PW, Schoch CL, Hyde KD, Wood AR, Gueidan C, Hoog GS de, Groenewald JZ (2009). Phylogenetic lineages in the Capnodiales. Studies in Mycology 64: 17-47.