Mesnieraceae Arx & Müller, Stud. Mycol. 9: 94 (1975).
MycoBank number: MB 80998; Index Fungorum number: IF 80998, Facesoffungi number: FoF 07871, 6 species.
Synonym: Stegasphaeriaceae Syd. & P. Syd., Annls mycol. 14(5): 364 (1916).
Parasitic on leaves, causing necrotic symptoms on leaves, or saprobic. Sexual morph: Mycelium hyaline, developing within host tissue. Ascomata densely gregarious, immersed, sphaerical, flattened or globose to subglobose, yellowish-green, fleshy, light with peridium composed of many cells, uni-loculate, with numerous asci and pseudoparaphyses. Ostiole present or lacking, usually opening apically with a pore, or with wide and large hole in mature ascomata, erumpent through the upper epidermis, comprising elongated columnar cells. Peridium thin-walled, hyaline, composed of many layers of flattened cells of textura angularis, or comprising a few layers of elongate cells. Hamathecium comprising numerous, hypha-like, filamentous, septate pseudoparaphyses, embedded in a gelatinous matrix. Asci 4–24-spored, bitunicate, cylindrical to clavate, or elongate- ellipsoidal, short-pedicellate, inner membrane thickened in the upper part, apex rounded, with or without a well- developed ocular chamber. Ascospores 2- to multi-seriate, ellipsoidal, dark brown to brown, or dark reddish-brown, 0–1-septate, thick-walled, constricted at the septum, with or without a mucilaginous sheath. Asexual morph: Undetermined
Type: Mesniera Sacc. & P. Syd.
Notes: Mesnieraceae was introduced by von Arx and Müller (1975) and type species is Mesniera rottlerae. Mesnieraceae includes the genera Bondiella, Mesniera and Stegasphaeria (Kirk et al. 2008). Hyde (1996) considered Bondiella as a good member in Mesnieraceae (Pirozynski 1972; Eriksson 1981) and observed, redescribed and illustrated Bondiella palmicola from leaf blades of dried fallen palm fronds, while Lumbsch and Huhndorf (2010) included four genera with the addition of Helochora. Helochora was isolated from Puya sp. in Chile, and described as a new genus by Sherwood (1979) and was accommodated in Polystigmataceae. It has ornamented spores which are uni-seriate in the asci. Hyde et al (2013) observed the type specimen of Helochora hypertropha and considered that Helochora does not belong to Mesnieraceae therefore Helochola was transferred to Sordariomycetes genera incertae sedis.