Zasmidium Fr., Summa veg. Scand., Sectio Post. (Stockholm): 407 (1849).
= Periconiella Sacc., in Saccardo & Berlese, Atti Inst. Veneto Sci. lett., ed Arti, Sér. 6 3: 727 (1885).
Index Fungorum number: IF 22396 128; Facesoffungi number: FoF 08574, 223 morphological species (Species Fungorum 2021), 53 species with molecular data.
Hyphomycetous (asexual morphs or asexual holomorphs) or Zasmidium with mycosphaerella-like sexual morphs; saprobic or mostly biotrophic, usually foliicolous, symptomless or causing various lesions, ranging from yellowish discolorations to distinct leaf spots. In plant pathogenic species, mycelium mostly immersed as well as superficial, rarely only immersed; hyphae branched, septate, hyaline or almost so to pigmented, pale olivaceous to brown, wall thin to somewhat thickened, immersed hyphae smooth or almost so to faintly rough, external hyphae distinctly verruculose to verrucose (in culture immersed hyphae usually smooth or almost so, aerial hyphae verruculose). Asexual morph: Stromata lacking to well-developed, pigmented. Conidiophores solitary, arising from superficial hyphae, lateral, occasionally terminal, in vivo (in plant pathogenic taxa) sometimes also fasciculate, arising from internal hyphae or stromata, semimacronematous to macronematous, in culture occasionally micronematous, cylindrical, filiform, subuliform, straight to strongly geniculate-sinuous, mostly unbranched, aseptate, i.e. reduced to conidiogenous cells, to pluriseptate, subhyaline to pigmented, pale olivaceous to medium dark brown, wall thin to somewhat thickened, smooth to verruculose; conidiogenous cells integrated, terminal, occasionally intercalary, rarely pleurogenous, or conidiophores reduced to conidiogenous cells, mostly polyblastic, sympodial, with conspicuous, somewhat thickened and darkened-refractive, planate loci. Conidia solitary or catenate, in simple or branched acropetal chains, shape and size variable, ranging from amero- to scolecosporous, aseptate to transversely plurieuseptate, subhyaline to pigmented, pale olivaceous to brown, wall thin to somewhat thickened, smooth or almost so to usually distinctly verruculose (in plant pathogenic species without superficial mycelium always verruculose), hila somewhat thickened and darkened-refractive, planate, conidial secession schizolytic. Sexual morph: Unknown (Adapted from Braun et al. 2013 and Videira et al. 2017).
Type species: Zasmidium cellare (Pers.) Fr.
Notes: Zasmidium was introduced by Fries (1849) with Z. cellare as type species. Zasmidium is characterized by solitary semimacronematous to macronematous conidiophores arising from superficial hyphae, integrated, terminal, occasionally intercalary conidiogeneous cells and solitary or catenate conidia ranging from amero- to scolecosporous, aseptate to transversely plurieuseptate, subhyaline to brown. Zasmidium accommodates stenella-like fungi belonging to Mycosphaerellaceae (Arzanlou et al. 2007; Braun et al. 2010; Videira et al. 2017). The holotype material of Zasmidium cellare which is based on Racodium cellare, is lost hence Videira et al. (2017) designated a neotype specimen from wall in wine cellar in Europe under the code CBS 146.36. Zasmidium morphologically resembles Stenella but can be differentiated based on the shape of conidiogenous loci (planate in Zasmidium vs pileate in Stenella) (Braun et al. 2013; Videira et al. 2017). Videira et al. (2017) synonymized Verrucisporota to Zasmidium based on morphology and phylogenetic analyses. Zasmidium is a distinct genus in Mycosphaerellaceae but this genus needs revision as the placement of several species in Zasmidium is doubtful due to lack of molecular data.