Ramularia Unger, Exanth. Pflanzen (Wien): 119 (1833).
= Mycosphaerella Johanson, Öfvers. K. Svensk. Vetensk.-Akad. Förhandl. 41(no. 9): 163 (1884) [1884-1885].
Index Fungorum number: IF 9691; Facesoffungi number: FoF 09222, 1,662 morphological species (1,252 species as Mycosphaerella and 410 species as Ramularia) (Species Fungorum 2020), 154 species with molecular data (71 species as Mycosphaerella and 83 species as Ramularia).
Saprobic on bark. Sexual morph: Unknown. Asexual morph: Mycelium immersed, hyphae pigmented. Stromata immersed, composed of brown, thick-walled hyphal cells. Conidiophores in dense fascicles, arising from stromata, olivaceous brown, smooth, simple, straight, subcylindrical, slightly geniculate-sinuous. Conidiogenous cells terminal, sub hyaline to pale olivaceous, smooth, proliferating sympodially, conidiogenous loci conspicuous, slightly thickened and darkened. Conidia solitary, ellipsoid-ovoid, obclavate-fusiform, subcylindrical, aseptate or septate, sub hyaline to pale olivaceous, smooth to verruculose, apex obtuse or subacute, base obconically truncate, hila hardly thickened and somewhat darkened (adapted from Videira et al. 2017).
Type species: Ramularia endophylla Verkley & U. Braun, in Verkley et al.
Notes: Mycosphaerella is one of the largest genera of ascomycetes, and comprises plant pathogens of economically important crops, as well as saprobic species. Mycosphaerella was introduced by Johanson et al. (1885) with M. punctiformis as type species. The sexual morph morphology is rather simple and uniform in Mycosphaerella, but the genus is problematic due to the variety of related asexual morphs (Arx 1983; Sutton and Hennebert 1994). Klebahn (1918) and Laibach (1922) proposed to separate groups of species from Mycosphaerella on the basis of their association with a particular asexual morph but these proposals were not widely accepted. The characters used to define asexual morph genera in Mycosphaerella are conidiomatal structure, conidial shape, size, and septation but these features are not phylogenetically informative (Crous et al. 2000, 2001; Verkley et al. 2004). Verkley et al. (2004) re-examined the lectotype material of M. punctiformis deposited in L and confirmed its identity. Recent studies based on phylogenetic analyses have reported that M. punctiformis comprises cryptic species that are morphologically similar (Crous et al. 2004, 2006; Videira et al. 2007). Verkley et al. (2004) reported that many strains in the CBS collection that had been morphologically recognized as M. punctiformis from Quercus, Acer and Tilia are actually heterogeneous in their sequences of the internal transcribed spacer (ITS) region. Verkley et al. (2004) designated an epitype of M. punctiformis with a specimen collected from the type host Quercus robur in The Netherlands and provided a phenotypic description of the sexual morph, and (syn) asexual morphs in culture. The Mycosphaerella-like sexual morphs are generally morphologically conserved and species are mainly differentiated based on morphology of their asexual morphs (Crous et al. 2009e). Mycosphaerella s. str. is characterised by Ramularia asexual morphs while Mycosphaerella s. lat. signifies several genera distributed over different families. Mycosphaerella and Ramularia are polyphyletic (Crous et al. 2007a, 2009e; Videira et al. 2015b, 2016). Since the name Ramularia (1833) is older than Mycosphaerella (1884), the former was selected over Mycosphaerella based on the one fungus = one name initiative (Wijayawardene et al. 2014; Rossman et al. 2015; Videira et al. 2015a, b). These two genera still have a long historical debate by many authors (Braun 1995; Crous et al. 2009c, e; Kirschner 2009; Videira et al. 2015b, 2016). Lately, several new genera were introduced to accommodate Mycosphaerella s. lat. and Ramularia s. lat. (Videira et al. 2016, 2017). Molecular markers available for Ramularia are ITS, LSU, SSU, Actin, BTUB, Calmodulin, Chs, GAPDH, Histone, RPB2 and TEF-1.