Acrospermaceae Fuckel, Jb. nassau. Ver. Naturk. 23–24: 92 (1870) [1869–70].
MycoBank number: MB 80430; Index Fungorum number: IF 80430; Facesoffungi number: FoF 06380, 52 species.
Saprobic, epiphytic or symbiotic on herbaceous plants. Sexual morph: Ascomata solitary or in groups, superficial or immersed in stromata, erect, elongate, with smooth or sometimes rough surface, dark brown to black, flattened, club-shaped to conoid, with a short stipe, swelling when moist, ostiolate. Peridium comprising two or three layers, an outer layer composed of dark brown cells of textura angularis, a central layer, composed of hyaline, sometimes pale brown tissue of elongated cells intertwined, and an inner layer composed of dense tissue of small, light brown cells. Hamathecium comprising narrow, long, hyaline, filiform pseudoparaphyses. Asci typically 8-spored, bitunicate, long, narrowly cylindrical, pedicellate, apically rounded with an ocular chamber. Ascospores fasciculate, filiform, hyaline, multi-septate, almost as long as the asci, smooth-walled, not fragmenting, without sheath, typically intertwined in a fascicle within the ascus. Asexual morph: Hyphomycetous. Conidiophores micronematous, pale brown, septate, branched or unbranched. Conidiogenous cells holoblastic, sympodial with denticles, pale brown, smooth-walled. Conidia cylindrical, long ellipsoid, pale yellow, 1–3-septate, smooth-walled.
Type: Acrospermum Tode.
Notes: Acrospermaceae was introduced with a single genus Acrospermum by Fuckel (1870) and since then its higher taxonomic placement has undergone various changes (Saccardo 1883; Rehm 1887; Ellis and Everhart 1892; Ainsworth et al. 1973; Barr 1990). The family was previously placed in the class Dothideomycetes family incertae sedis, due to its uncertain position (Hyde et al. 2013). Two genera, Acrospermum and Oomyces are currently accepted (Lumbsch and Huhndorf 2010; Wijayawardene et al. 2018). Acrospermum is characterised by erect, elongate, usually brown, superficial ascomata that are more or less club-shaped and are solitary or in small groups, with long paraphyses which resemble ascospores. Oomyces is considered to be clavicipitalean (Diehl 1950) as it has conoid, yellowish white, multi-locular stromata, bitunicate asci and lacks pseudoparaphyses (Eriksson 1981). No monograph of the genus is available. Riddle (1920) reviewed Acrospermum and introduced A. maxoni and A. graminum var. foliicolum based on asexual morphs. Presently, the asexual morphs of Acrospermaceae comprise members of Dactylaria and Gonatophragmium (Wijayawardene et al. 2018). Dactylaria was shown to be polyphyletic by Bussaban et al. (2005) and is heterogenous (Seifert et al. (2011). Gonatophragmium was also found to be an asexual morph of Acrospermum by Kirk et al. (2008), but Seifert et al. (2011) did not assign it to any taxonomic rank. A Blast search of an LSU sequence of Gonatophragmium triuniae showed closed hits to Acrospermum adeanum (Crous et al. 2014). We therefore, agree with Wijayawardene et al. (2018) and include Gonatophragmium in Acrospermaceae until further data becomes available. The hyphomycetous genus Pseudovirgaria was introduced by Shin et al. in Arzanlou et al. (2007), with P. hyperparasitica as type species. Pseudovirgaria is assigned to Capnodiales, genera incertae sedis in Index Fungorum (2020), while it was mentioned as Dothideomycetes genera incertae sedis in Wijayawardene et al. (2018). In our phylogenetic analysis, two species of Pseudovirgaria clustered in Acrospermales. Pseudovirgaria is a hyphomycetous genus and morphologically resembles Gonatophragmium in having cylindric-clavate, thin-walled conidia. Therefore, we include Pseudovirgaria in Acrospermaceae based on phylogenetic evidence, and morphological resemblance to asexual genera of Acrospermaceae. Descriptions and illustrations of the asexual morphs of Acrospermaceae can be seen in previous studies (i.e. Crous et al. 2014; Berger et al. 2015; Shamsi et al. 2017)