Anamorph: not known.
Teleomorph: ascostromata perithecia, 100-300 µm diam., globose to pyriform, sometimes distinctly papillate, the substrate stained purple-red. Peridium composed of angular cells, strongly melanized especially in the ostiolar region. Interascal tissue of well-developed pseudoparaphyses. Asci 130-210 x 30-43 µm, not numerous, clavate, fissitunicate, 8-spored. Ascospores biseriately arranged, 44-58 x 13-18.5 µm, narrowly ellipsoidal, often somewhat clavate and asymmetrical, pale yellow to pale brown, smooth, with the upper part more rounded than the lower part, (13-) 15- to 19-septate, with 2-5 longitudinal or oblique septa, with a broad gelatinous epispore.
Not formally assessed. The species might be considered as threatened but the known host plant is very widespread and the fungus could well be under-recorded. It should probably be considered to be Data Deficient.
This is the only dictyosporous species of Massariosphaeria known from GB&I.
On dead tissues of Ammophila arenaria.
In GB&I, only known from a single site on the island of Rhum (VC104).