Mycosphaerella, one of the largest genera of ascomycetes, encompasses several thousand species and has anamorphs residing in more than 30 form genera. Although previous phylogenetic studies based on the ITS rDNA locus supported the monophyly of the genus, DNA sequence data derived from the LSU gene distinguish several clades and families in what has hitherto been considered to represent the Mycosphaerellaceae. Several important leaf spotting and extremotolerant species need to be disposed to the genus Teratosphaeria, for which a new family, the Teratosphaeriaceae, is introduced. Other distinct clades represent the Schizothyriaceae, Davidiellaceae, Capnodiaceae, and the Mycosphaerellaceae. Within the two major clades, namely Teratosphaeriaceae and Mycosphaerellaceae, most anamorph genera are polyphyletic, and new anamorph concepts need to be derived to cope with dual nomenclature within the Mycosphaerella complex.Taxonomic novelties: Batcheloromyces eucalypti (Alcorn) Crous & U. Braun, comb. nov., Catenulostroma Crous & U. Braun, gen. nov., Catenulostroma abietis (Butin & Pehl) Crous& U. Braun, comb. nov., Catenulostroma chromoblastomycosum Crous& U. Braun, sp. nov., Catenulostroma elginense (Joanne E. Taylor& Crous) Crous & U. Braun, comb. nov., Catenulostroma excentricum (B. Sutton & Ganap.) Crous & U. Braun, comb. nov., Catenulostroma germanicum Crous & U. Braun, sp. nov., Catenulostroma macowanii (Sacc.) Crous & U. Braun, comb. nov., Catenulostroma microsporum (Joanne E. Taylor & Crous) Crous & U. Braun, comb. nov., Catenulostroma protearum (Crous & M.E. Palm) Crous & U. Braun, comb. nov., Penidiella Crous & U. Braun, gen. nov., Penidiella columbiana Crous & U. Braun, sp. nov., Penidiella cubensis (R.F. Castañeda) U. Braun, Crous& R.F. Castañeda, comb. nov., Penidiella nectandrae Crous, U. Braun & R.F. Castañeda, nom. nov., Penidiella rigidophora Crous, R.F. Castañeda & U. Braun, sp. nov., Penidiella strumelloidea (Milko & Dunaev) Crous & U. Braun, comb. nov., Penidiella venezuelensis Crous & U. Braun, sp. nov., Readeriella blakelyi (Crous & Summerell) Crous & U. Braun, comb. nov., Readeriella brunneotingens Crous & Summerell, sp. nov., Readeriella considenianae (Crous & Summerell) Crous & U. Braun, comb. nov., Readeriella destructans (M.J. Wingf. & Crous) Crous & U. Braun, comb. nov., Readeriella dimorpha (Crous& Carnegie) Crous & U. Braun, comb. nov., Readeriella epicoccoides (Cooke & Massee) Crous & U. Braun, comb. nov., Readeriella gauchensis (M.-N. Cortinas, Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Readeriella molleriana (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Readeriella nubilosa (Ganap. & Corbin) Crous & U. Braun, comb. nov., Readeriella pulcherrima (Gadgil & M. Dick) Crous & U. Braun, comb. nov., Readeriella stellenboschiana (Crous) Crous & U. Braun, comb. nov., Readeriella toledana (Crous & Bills) Crous & U. Braun, comb. nov., Readeriella zuluensis (M.J. Wingf., Crous & T.A. Cout.) Crous & U. Braun, comb. nov., Teratosphaeria africana (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria alistairii (Crous) Crous & U. Braun, comb. nov., Teratosphaeria associata (Crous & Carnegie) Crous & U. Braun, comb. nov., Teratosphaeria bellula (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria cryptica (Cooke) Crous & U. Braun, comb. nov., Teratosphaeria dentritica (Crous & Summerell) Crous & U. Braun, comb. nov., Teratosphaeria excentrica (Crous& Carnegie) Crous & U. Braun, comb. nov., Teratosphaeria fimbriata (Crous & Summerell) Crous & U. Braun, comb. nov., Teratosphaeria flexuosa (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria gamsii (Crous) Crous & U. Braun, comb. nov., Teratosphaeria jonkershoekensis (P.S. van Wyk, Marasas & Knox-Dav.) Crous & U. Braun, comb. nov., Teratosphaeria maxii (Crous) Crous & U. Braun, comb. nov., Teratosphaeria mexicana (Crous) Crous & U. Braun, comb. nov., Teratosphaeria molleriana (Thüm.) Crous & U. Braun, comb. nov., Teratosphaeria nubilosa (Cooke) Crous & U. Braun, comb. nov., Teratosphaeria ohnowa (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria parkiiaffinis (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria parva (R.F. Park& Keane) Crous & U. Braun, comb. nov., Teratosphaeria perpendicularis (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria pluritubularis (Crous & Mansilla) Crous& U. Braun, comb. nov., Teratosphaeria pseudafricana (Crous & T.A. Cout.) Crous & U. Braun, comb. nov., Teratosphaeria pseudocryptica (Crous) Crous & U. Braun, comb. nov., Teratosphaeria pseudosuberosa (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria quasicercospora (Crous & T.A. Cout.) Crous & U. Braun, comb. nov., Teratosphaeria readeriellophora (Crous & Mansilla) Crous & U. Braun, comb. nov., Teratosphaeria secundaria (Crous & Alfenas) Crous & U. Braun, comb. nov., Teratosphaeria stramenticola (Crous & Alfenas) Crous& U. Braun, comb. nov., Teratosphaeria suberosa (Crous, F.A. Ferreira, Alfenas & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria suttonii (Crous & M.J. Wingf.) Crous & U. Braun, comb. nov., Teratosphaeria toledana (Crous & Bills) Crous& U. Braun, comb. nov., Teratosphaeriaceae Crous & U. Braun, fam. nov.