Asteromassaria macrospora (Desm.) Höhn., Sber. Akad. Wiss. Wien, Math.-naturw. Kl., Abt. 1 126(4-5): 368 (1917) Fig. 1
≡ Sphaeria macrospora Desm., Annls Sci. Nat., Bot., sér. 3 11(2): 350 (1849)
Index Fungorum number: IF 120830; Facesoffungi number: FoF 06213
Saprobic on unidentified dry twigs in terrestrial habitat. Sexual morph: Ascomata 0.9–1.2 mm high × 0.9–1.3 mm diam. (x̅ = 1.5 × 1.1 µm, n = 10), solitary, scattered, or in small groups, immersed, erumpent, depressed globose or subglobose, medium to large, black, ostiolate. Ostiole papillate, opening via a minute slit or a small conical swelling in the bark. Peridium 53–65 μm, 1-layered, composed of small pigmented thick-walled compressed cells, base consists of small, pigmented, thick-walled cells of textura angularis and apex comprises comparatively large cells. Hamathecium 3.5–4 μm of dense, cellular, filiform, broad, septate pseudoparaphyses, embedded in a gelatinous matrix. Asci 200–245 µm × 36–40 µm (x̅ = 230 × 38 µm, n = 10), 8-spored, bitunicate, fissitunicate, broadly cylindrical to broadly cylindro-clavate, with a short, narrow, thick pedicel, rounded at the apex with a small ocular chamber. Ascospores 50–56 µm × 16–22 µm (x̅ = 54 × 19 µm, n = 10), biseriate, partially overlapping, narrowly oblong with broadly to narrowly rounded ends, hyaline, 1-septate, constricted at septum, smooth to verrucose, without a mucilaginous sheath. Asexual morph: Scolicosporium macrosporium (Berk.) B. Sutton. Acervuli immersed in bark, brown, discrete, up to 200 μm diam., opening by irregular rupture of the overlaying tissues. Conidiophores cylindrical, 1–2 septate, up to 30 μm long and 3–5 μm wide. Conidiogenous cells holoblastic, enteroblastic, 1-2-annellate, cylindrical. Conidia 140–190 µm × 12–18 μm, fusoid, brown, with paler or hyaline ends, 7–10 transverse septate, smooth-walled, with a tapered apex and truncate base.
Material examined – FRANCE, Normandie, in the park of Lébisey near Caen, on unidentified dry twigs, 6 April 1845, Roberge (S-F73254, holotype).
Economic significance – The genus Asteromassaria seems to be a source of an enzyme capable of breaking the middle lamella of bark cells and a biological agent of interest able to digest wood (Shoemaker et al. 2003). Asteromassaria has also been reported to be associated to Mulberry diseases of Japan (Tanaka 2005).