Pleospora Rabenh. ex Ces. & De Not., Comm. Soc. crittog. Ital. 1(4): 217 (1863)
= Stemphylium Wallr., Fl. crypt. Germ. (Norimbergae) 2: 300 (1833)
= Cleistotheca Zukal, Österreichische Botanische Zeitschrift 53 (5): 163 (1893)
= Cleistothecopsis Stevens & True, Illinois Agric. Exper. Stat. Bull. Nr. 220: 507 (1919).
Habitat terrestrial or aquatic, saprobic or parasitic. Ascomata small to medium-sized, immersed, erumpent to superficial, base not easy to remove from the substrate, broadly to narrowly oblong and flattened, ostiolate. Ostiole papillate, black, smooth, ostiolar canal filled with hyaline cells. Peridium thin, usually with two layers, thick at the sides and thinner at the base, outer layer heavily pigmented thick-walled cells of textura angularis, inner layer composed of hyaline thin-walled cells of textura angularis, coriaceous. Hamathecium of cellular, hyaline, septate, broad, dense pseudoparaphyses. Asci 8-spored, bitunicate, fissitunicate, cylindrical to clavate, with furcate pedicel and minute ocular chamber. Ascospores uniseriate or partially overlapping, mostly ellipsoidal, muriform, brown or pale brown, with or without sheath. Asexual morph: Stemphylium. Mycelium immersed or nearly superficial, brown. Stroma sometimes present. Conidiophores macronematous, mononematous, scattered or caespitose, unbranched or rarely loosely branched, straight or flexuous, usually nodose with a number of vesicular swellings, pale to mid brown or olivaceous brown, smooth or in part verruculose. Conidiogenous cells monoblastic, integrated, terminal, percurrent, at first clavate or subsphearical with the wall at the apex thin. Conidia solitary, dry, acrogenous, oblong, rounded at the ends, ellipsoidal, obclavate or subsphearical, pale to mid dark or olivaceous brown, smooth, verrucose or echinulate, muriform, often constricted at one or more of the septa, cicatrized at the base. Colonies effuse, grey, brown, olivaceous brown or black, velvety or cottony (Ellis 1971).
Type species: Pleospora herbarum (Pers.) Rabenh., Klotzschii Herb. Viv. Mycol. 2: no. 547 (1854).