Cercosporidium Earle, Muhlenbergia 1(2): 16 (1901).
Index Fungorum number: IF 7547; Facesoffungi number: FoF 08485, 10 morphological species (Species Fungorum 2021), 2 species with molecular data.
Foliicolous. Mycelium internal, hyaline to pale olivaceous brown, or dark brown. Stromata small to developed, olivaceous brown to brown. Conidiophores solitary or in fascicles, micro- to macronematous, sometimes irregular in width, very pale to olivaceous brown, smooth to rough, simple or branched, straight to geniculate-sinuous, sometimes reduced to conidiogenous cells. Conidiogenous cells terminal, proliferation sympodial or percurrent, mono- or polyblastic, with conidiogenous loci slightly to distinctly thickened and darkened. Conidia solitary in vivo, rarely catenate in vitro, hyaline to pale olivaceous, smooth to verruculose, thick-walled, cylindrical, ovoid, obovoid or obclavate, straight or slightly curved, slightly thickened, truncate or short obconical truncate at the base, broadly rounded or beak-like at the apex, euseptate, hilum thickened, darkened and refractive (Adapted from Videira et al. 2017).
Type species: Scolicotrichum euphorbiae Tracy & Earle
Notes: Cercosporidium was introduced by Earle (1901) with S. euphorbiae as type species. Though Earle (1901) selected Scoletotrichum euphorbiae as the type species of Cercosporidium, the combination was not validly published in the genus. A revised description of the genus was published by Deighton (1967) and a combination of the older name Cladosporium chaetomium was introduced. This treatment was followed by several authors (Baker et al. 2000, Crous and Braun 2003). Braun et al. (2013) mentioned Cercosporidium helleri Earle as the type species of Cercosporidium. The status of the genus Cercosporidium underwent many debate for several years. von Arx (1983), Castaneda and Braun (1989) and Braun (1995) argued that Cercosporidium is a synonym of Passalora. Pons and Sutton (1996), Baker et al. (2000) reported that Cercosporidium is a distinct genus. Videira et al. (2017) resurrected Cercosporidium based on morphology and phylogeny. Cercosporidium is characterized by a well-developed stroma, and geniculate-sinuous conidiophores with rim-like conidial loci, conidia solitary, sub cylindrical to obclavate, pale colored, reasonably thick-walled, smooth to verruculose surface, and darkened hila. Cercosporidium is a well-supported genus in Mycosphaerellaceae.