Jaczewskiella Murashk., Mater. Mikol. Fitopat. Ross. 5(2): 5 (1926).
Index Fungorum number: IF 8647; Facesoffungi number: FoF 08620, 1 morphological species (Species Fungorum 2022), no molecular data available.
Saprobic on host. Sexual morph: Unknown. Asexual morph: Conidiomata stromatic, cupulate, with a more or less well-developed stalk, sometimes sessile, large, scattered, composed of light brown to brown prismatic or oblong cells, darker and thick-walled towards the periphery. Conidiophores lacking. Conidiogenous cells lining the whole inner surface of the conidiomata, holoblastic, annellidic, indeterminate, discrete, cylindrical, thin-walled, smooth, light brown, with a single percurrent proliferation, margin uneven, fimbriate. Conidia solitary, clavate, obclavate, broad ellipsoid, smooth, with transverse and oblique to vertical septa, constricted at transverse septa, light brown, transparent (adapted from Mel'nik and Popushoj 1992; Videira et al. 2017).
Type species: Jaczewskiella altajensis Murashk.
Notes: Jaczewskiella is characterised by stromatic, cupulate conidiomata, holoblastic, annellidic conidiogenous cells and solitary, clavate, obclavate, broadly ellipsoid conidia. Sutton (1977) considered Jaczewskiella as a synonym of Stigmina. Shkarupa (1992) and Braun and Mel'nik (1996) considered Jaczewskiella as a distinct genus based on the cupulate conidiomata and brown phragmo- to dictyoconidia. The placement of Jaczewskiella in Mycosphaerellaceae is doubtful.