Planistromellaceae M.E. Barr, Mycotaxon 60: 437 (1996).

MycoBank number: MB 81919; Index Fungorum number: IF 81919; Facesoffungi number: 06689, 33 species.

Biotrophic, hemibiotrophic or saprobic on leaves and stems of various plants in terrestrial habitats. Sexual morph: Ascostromata multi- or uniloculate, immersed to erumpent through cracking or splitting of the host tissue, solitary to gregarious, with periphysate ostioles, with or without papilla. Cells of ascostromata thick-walled, composed of several layers of dark brown cells, arranged in a textura angularis. Locules ovoid to globose, developing in the same stroma of the conidiogenous and/or spermatogenous locules, collapsed with the empty locule, which previously produced conidia or spermatia or both, ostiole periphysate. Peridium of locules composed of a few layers of hyaline to light brown flattened cells. Hamathecium lacking pseudoparaphyses, interascal cells abundant even at maturity. Asci 8-spored, bitunicate, fissitunicate, oblong, clavate to nearly cylindrical, with a pedicel and with an ocular chamber, forming in a basal layer, often interspersed with and covered by cellular remnants of interthecial tissues. Ascospores overlapping 1–3-seriate, ellipsoid to broadly obovoid, hyaline or lightly pigmented, yellowish to brownish, aseptate or 1–2-trans-septate, thin-walled, with or without gelatinous sheath, guttulate. Asexual morph: Coelomycetous. Conidiomata subepidermal, dark, immersed to erumpent, solitary to gregarious, pycnidia, locules or acervuli in a stroma or bearing conidia over stroma surface prior to locule formation, ostiolate. Conidiomata walls comprising several layers with cells of textura angularis, the outer layers composed of dark thick-walled cells, lighter towards the inner layers of hyaline cells. Conidiogenous cells short cylindric, conidiogenesis holoblastic, hyaline, smooth. Conidia oblong, ellipsoid-cylindric, hyaline to brown, aseptate or 1-multitrans-septate, smooth-walled or verruculose, with or without one or more apical appendages. Spermatial state developing in the same or separate locules. Spermatogenous cells discrete or integrated, phialidic, cylindric to elongate-conical, determinate, hyaline, smooth. Spermatia bacillary, hyaline, aseptate, smooth-walled.

Type: Kellermania Ellis & Everh.

Notes: Planistromellaceae was introduced by Barr (1996) and belongs to Botryosphaeriales (Minnis et al. 2012; Monkai et al. 2013). Lumbsch and Huhndorf (2010) included the genera Comminutispora, Eruptio, Loratospora., Microcyclus, Mycosphaerellopsis, Planistroma and Planistromella in Planistromellaceae based on morphology. Phylogenetic analysis based on SSU, ITS and LSU sequence data by Minnis et al. (2012) showed that Kellermania, Piptarthron, Planistroma and Planistromella should be treated as a single genus, thus, they synonymized them under Kellermania (oldest name). However, Monkai et al. (2013) indicated that the type species of Kellermania, which is also the type of Planistromella, clustered separately from Planistroma based on LSU and ITS sequence data. Planistroma was accepted as a distinct genus. The family was revised to accommodate Kellermania, Planistroma Mycosphaerellopsis and Umthunziomyces based on morphology and molecular data (Monkai et al. 2013; Phillips et al. 2019).