Thallus small, 2-4 mm diam. or irregular and following contours in the rock, areolate. Areoles (200-) 350-500 (-1000) µm diam., 150-250 (-300) μm thick, irregular, usually polygonal, the surface flat or shallowly convex, grey-brown, not or thinly white-pruinose, the radial sides often dark brown. Upper cortex 8-15 μm thick, of 1-2 (-3) layers of brown-walled cells, epinecral layer patchy and variably developed, 0-30 μm thick. Algal layer 65-120 μm thick, with algal cells 8-17 μm diam. Medulla not or weakly J+, 80-180 μm thick, fairly dense, with abundant crystals from the substrate, in places with necrotic brown parts of the host lichen. Anamorph: conidiomata pycnidia, in locules within the thallus, the walls hyaline, mid brown immediately around the ostiole. Conidiogenous cells conical to doliiform, proliferating peruccrently. Conidia 4-5.5 × 0.5-1 μm, narrowly bacillar, aseptate, hyaline. Teleomorph: ascomata perithecia, 105-175 μm diam., completely immersed, rarely prominent, 1-3 (-5) in each areole, visible from above due to blackening around the ostiole which may appear distinctly papillate. Peridium 10-15 μm thick, hyaline except for a small apical area of brown pigmentation, composed of 3-4 layers of rather thick-walled flattened cells. Involucrellum not clearly present. Interascal tissue absent, periphysoids 14-22 × 2.5-4 μm in size. Asci 45-60 × 13-18 (-26) μm, clavate to saccate, distinctly thick-walled when young but rather thin-walled at maturity, 8-spored. Ascospores (12.5-) 13.5-15 (-16) x (5-) 5.5-6.5 μm, ellipsoidal, L/W ratio 2.2-2.6, mostly aseptate but with a small proportion (~10%) with a median septum, hyaline, thin- and smooth-walled, without an epispore, gelatinous sheath or appendages.