Pleomassariaceae M.E. Barr, Mycologia 71(5): 949 (1979).

MycoBank number: MB 81634; Index Fungorum number: IF 81634; Facesoffungi number: FoF 06430, 58 species.

Saprobic or parasitic on woody substrates or lichens in terrestrial environments. Sexual morph: Ascomata medium to large, solitary, scattered or in groups, superficial to immersed in or erumpent from the peridium of woody host, globose or depressed globose, ostiolate. Ostiole flattened, papillate, open via minute slit or a small conical swelling in the host. Peridium thickened at sides, thin at the base and at the apex, comprises of one to several cell layers. Hamathecium comprising narrow cellular pseudoparaphyses. Asci 8-spored, bitunicate, fissitunicate, oblong, cylindrical or clavate, with a furcate pedicel and minute ocular chamber. Ascospores partially overlapping, obliquely 1–2-seriate, clavate, oblong to ellipsoidal, brown, mostly distoseptate, often euseptate, 1-septate to multi-septate or muriform, constricted at the septa, smooth-walled to verruculose, surrounded by a gelatinous sheath. Asexual morph: Coelomycetous or hyphomycetous, Beverwykella, Myxocyclus, Prosthemium are currently reported asexual morphs for the family.

TypeProsthemium Kunze

NotesPleomassariaceae was introduced with Pleomassaria as the type by Barr (1979b) to include fungi characterized by distoseptate, dark brown ascospores and ascomatal walls which are thickened at sides and thin at the base (Hyde et al. 2013, Wijayawardene et al. 2014a). After the initial introduction of Asteromassaria and Splanchnonema into the family (Barr 1979b), many genera were included into or excluded from the family during past revisions based on host, morphology and asexual morph (Hawksworth 1985, Aptroot 1991, Barr 1993a). Based on the morphological similarities excluding ascospore septation, Pleomassaria was treated as a synonym of Splanchnonema (Barr 1993a), though it was not followed by many studies (Zhang et al. 2012b). Molecular studies conducted by Zhang et al. (2009c) placed Pleomassariaceae within Melanommataceae similar to the study by Tanaka et al. (2010). Subsequently Zhang et al. (2012b) showed a well-supported monophyletic clustering of Pleomassaria siparia and four Prosthemium species basal to Melanommataceae. Hence, Pleomassariaceae was reinstated as a separate family in Pleosporales. Lumbsch & Huhndorf (2010) accepted Lichenopyrenis, Peridiothelia, Pleomassaria, Splanchnonema and Asteromassaria in Pleomassariaceae; however, the latter was excluded by Hyde et al. (2013). Wijayawardene et al. (2018) accepted seven genera in the family, Beverwykella, Lichenopyrenis, Myxocyclus, Peridiothelia, Prosthemium (previously known as Pleomassaria) Pseudotrichia and Splanchnonema. Pleomassariaceae consists of both sexual and asexual morphs. The asexual morphs include both hyphomycetous (Beverwykella) and coelomycetous (Myxocyclus and Prosthemium) taxa. Long before the inclusion of molecular phylogeny in fungal identification, doubts arose on the connection between Pleomassaria siparia and Prosthemium betulinum based on observations of the two spore types in the same host sites (Winter 1887, Allescher 1903). Hantula et al. (1998) confirmed P. betulinum as the asexual morph of P. siparia. According to International Code of Nomenclature for algae, fungi and plants (McNeil et al. 2012), Wijayawardene et al. (2014a) and Rossman et al. (2015) proposed to adopt the older asexual typified name Prosthemium as the generic name over the younger sexual name Pleomassaria. Even though Prosthemiaceae (1847) was validated before Pleomassariaceae (1979), it was proposed to conserve the family name Pleomassariaceae to maintain the nomenclatural stability rather than to adopt the long forgotten asexual family name Prosthemiaceae. This is because the name Prosthemiaceae has never been used in fungal classification since its introduction.