Hysterium angustatum  

Anamorph: only known in culture. Conidiomata pycnidial, ovoid, short-necked, the wall membranous, composed of interwoven hyphae.  Conidia 2-3 x 0.5-1 µm in size (Bisby 1941), cylindrical with rounded ends or allantoid, hyaline, smooth, aseptate.

Teleomorph: Ascostromata 300-2000 x (150-) 250-300 µm, 200-300 µm tall, elongate, narrowly elliptical to fusiform in outline, straight or irregularly curved, ovate to ± doliiform in vertical section, constricted at the base, scattered or gregarious, superficial or nearly so, dull black, with a conspicuous longitudinal cleft and often with inconspicuous parallel striations, the cleft gradually widening to expose the hymenium, which is coloured dark brown by the ascospores. Peridium 30-50 µm thick, side walls composed of very dark, near opaque, thick-walled brown-black cells, basal region similar, with a layer of hyaline thin-walled cells forming the cavity floor. Interascal tissue of paraphysoids ca 1.5 µm diam, filiform with rounded ends, hyaline, smooth, sparsely septate, branched and sometimes anastomosed, exceeding the asci and plugging the ascomatal slit when dry. Asci 64-120 x 8-14 µm, cylindrical-clavate, stalked, tapering to a rounded or irregular base, thick-walled, fissitunicate, apex rounded, I-, 8-spored, arising in parallel from the cavity floor. Ascospores 16-30 x 4-8.5 µm (one ascospore had dimensions of 45 x 11 µm), 3-septate (rarely 4-septate), narrowly ellipsoidal-ovoid to cylindrical with rounded ends, often with one side straight, reddish brown, slightly constricted at the septa, the end cells concolorous or slightly paler than median cells.