Massariosphaeria palustris  

Anamorph: not known. The teleomorph can be produced in culture.
Teleomorph: ascostromata perithecial, 160-250 µm diam., scattered, globose, black, subepidermal, the ostiolar region papillate and pushing up the epidermis. Peridium composed of brown polygonal cells, uneven in thickness, 40-55 µm thick at the sides and to 25 µm at the base. Asci 130-160 x 28-34 µm, few in number, broadly clavate, short-stalked, thick-walled and fissitunicate, 8-spored. Ascospores arranged irregularly bi- or triseriately above, uniseriately below, 37-42 x 11-12 µm, broadly fusiform to fusiform-ellipsoidal, brown, 6- to 8-septate (mostly 7-septate), constricted at the septa, asymmetrical, with 3 to 4 cells in the upper portion and 4 to 5 cells in the lower, 3rd or 4th cells from the apex enlarged, the epispore thick, punctate, surrounded by a gelatinous sheath.