Acrospermum Tode, Fung. mecklenb. sel. (Lüneburg) 1: 8 (1790), MycoBank: MB 54
Possible synonyms: Scleroglossum Pers., J. Colorado-Wyoming Acad. Sci.: no. 671 (1820)
Xyloglossum Pers., Traité sur les Champignons Comestibles (Paris): 140,144 (1818)
Saprobic or epiphytic on herbaceous plants. Sexual state: Ascomata solitary or in groups, superficial, club-shaped to conoid, erect, uni-locular, brown to blackish when dry, with a short stipe or sessile, flattened when dry, swelling when moist, ostiole large, apex rounded. Peridium in horizontal section comprising three layers, an outer layer comprising dark brown cells of textura angularis , a central thick layer, comprising pale brown tissue of gelatinized hyphae with elongated cells, and an inner layer comprising dense tissue of small, light brown cells. Hamathecium of narrow, long, pseudoparaphyses. Asci 8-spored, bitunicate, narrowly cylindrical, pedicellate, with an ocular chamber. Ascospores fasciculate, filiform, hyaline, multi-septate, almost as long as the asci, smooth-walled. Asexual state: Hyphomycetous. Conidiophores micronematous, pale brown, septate, branched or un-branched. Conidiogenous cells holoblastic, sympodial with denticles, long cylindrical, pale brown, smooth-walled. Conidia cylindrical, long ellipsoid, pale yellow, 1–3-septate, apically rounded, smooth-walled (Webster 1956).
Notes : Acrospermum includes 66 species epithets (Index Fungorum 2013). The genus was established by Tode (1790) and has superficial, club-like ascomata, narrowly cylindrical, bitunicate asci and filiform, multi-septate, hyaline ascospores (Riddle 1920). Eriksson (1981) redescribed the type species A. compressum and another similar species A. graminum. Molecular data showed that these two species can be clearly separated (Stenroos 2010). Webster (1956) also concluded after studying the asexual morphs in culture.
Type species : Acrospermum compressum Tode, Fung. mecklenb. sel. (Lüneburg) 1: 8 (1790), MycoBank: MB140891
Fig. Acrospermum cf. compressum (Material examined: VANUATU, Santo Island, South Santo, on decaying leaves of Pandanus sp., 31 October 1996, E.H.C. McKenzie HKU (M) 5005, IFRD 210–003). a, b Dry black ascomata on host surface. c Ascomata with short stipe. d Ascomata with large ostiole. e Ascoma in horizontal section. f, g Three layers of peridium. h-j Narrowly cylindrical asci. k, l Filiform ascospores. Scale bars: a–d =200μm, e–j =50μm, h–l =10μm