Anamorph: conidiomata 200-450 µm diam., spherical, immersed in dead host tissue, scattered, visible from the surface only as minute hardly papillate ostioles surrounded by inconspicuous grey discoloration. Peridium thin, composed of 2-3 layers of ± thick-walled dark brown angular cells. Conidiophores absent or reduced to short subtending cells lining the entire inner surface of the conidioma. Conidiogenous cells 5-7 x 3-5 µm, doliiform to shortly cylindrical and tapering towards the apex, ? annellidic. Conidia 12-19 x 4-7 μm, ellipsoidal, dark brown, in mass almost black, 3-septate, slightly constricted at the septa, sometimes slightly verrucose, with an apical appendage and sometimes a small basal appendage.
Teleomorph: not known.
Not formally assessed, but the species appears to be common.
On dead stems of Phragmites australis; also recorded on Ammophila, Nardus and Spartina.
Throughout suitable habitat in England, also known from Harris and Lewis (Outer Hebrides).