Cercosporella Sacc., Michelia 2(no. 6): 20 (1880).
Index Fungorum number: IF 7546; Facesoffungi number: FoF 08484, 71 morphological species (Species Fungorum 2021), 5 species with molecular data.
Phytopathogenic, mostly causing leaf spots. Asexual morph: Hyphae restricted to intercellular spaces and forming cup- or bowl-shaped appressoria, 7–17 μm diam that attach to walls of mesophyll cells. Conidiophores emerging through stomata or erumpent through the cuticle, straight, subcylindrical to geniculate-sinuous, hyaline, sometimes lightly pigmented near the base, more or less thin-walled and smooth. Conidiogenous cells integrated, terminal, polyblastic, sympodial, mostly conspicuously geniculate, conidiogenous loci conspicuous, hyaline but refractive, thickened and raised in the shape of a truncated cone (ultrastructure). Conidia formed singly, hyaline, sub cylindrical to obclavate, sometimes fusiform, 1- to multiseptate, usually thin-walled and smooth, apex obtuse, base often rounded to truncate or obconically truncate, hilum thickened, not darkened but refractive (Adapted from Braun 1995 and Kirschner 2009)
Type species: Cercosporella virgaureae (Thüm.) Allesch (≡ Ramularia virgaureae Thüm.).
Notes: Cercosporella was introduced by Saccardo (1880) with C. virgaureae as type species. Cercosporella is characterized by subcylindrical to geniculate-sinuous conidiophores, terminal, polyblastic conidiogenous cells, sub cylindrical to obclavate conidia. The taxonomic confusion between Cercosporella and Ramularia has been discussed by several authors (Braun 1995, 1998; Kirschner 2009; Videira et al. 2016). Cercosporella differs from Ramularia in having an appressorium feature to stick to the plant cells and by having a discrete ultrastructure of conidiogenous scars which is flat like a truncate cone. Kirschner (2009) mentioned that Cercosporella and Ramularia are phylogenetically distinct based on LSU sequence data. The phylogenetic analyses of Videira et al. (2016) based on LSU and rpb2 sequences data were in agreement with the result of Kirschner (2009). The type species, Cercosporella virgaureae, was found from the host Solidago virgaureae and collected in Austria. Videira et al. (2016) observed strains of this species from Brazilean and Korean origin and reported 100 % identity to the freshly collected isolate of Cercosporella virgaureae from Germany. Currently, Cercosporella is a distinct and well-supported genus in Mycosphaerellaceae.