Colonies dispersed, superficial, black, arising on the surface of the host. Mycelium immersed, composed of brownish, thin-walled hyphae and irregular clumps of cells from which conidia are produced.
Anamorph: conidiomata absent. Conidiophores not branched, brown, septate, irregular and poorly differentiated. Conidiogenous cells subcylindrical to subglobose, grey to brown, not proliferating. Conidia arising singly, mostly 6-16 µm diam., irregular in form but usually globose to cuboid, muriform, composed of 8-10 cells when fully developed, individual cells mainly 4-5 µm diam., dark grey to brown, the cell wall with irregular melanized patches, smooth, without an epispore or gelatinous sheath.
Teleomorph: not known.
Not evaluated by Woods & Coppins (2012), but listed as Nationally Rare. Possibly overlooked for other black powdery species.
On thalli of Lobaria pulmonaria and Xanthoria parietina, not causing significant damage to the thallus.
Known from two sites on Skye (VC104 N Ebudes) and one on North Uist (VC110 Outer Hebrides).