Naetrocymbe saxicola  

Thallus immersed to superficial, brownish grey (often discoloured by cyanobacteria), often minutely mottled, sometimes clearly delimited, lichenized with Trentepohlia.
Anamorph: conidiomata pycnidia, frequent, 60-80 μm diam., ± half-immersed in the substratum, subglobose to oblate with a rather large ostiole. Conidiomatal wall black, composed of 2-3 layers of very dark brown thick-walled angular cells. Conidiophores absent. Conidiogenous cells lining the inner wall, (3-) 5-6 x (2-) 2.5-3.5 µm, shortly cylindrical with a tapered apex, proliferating percurrently. Conidia 3.5-5 × ca 1 μm, cylindrical to bacillar, aseptate, hyaline, thin- and smooth-walled, without an epispore or gelatinous sheath.
Teleomorph: ascomata perithecia, 120-150 µm diam., ± globose, half to almost completely immersed in pits in rock, the apex black, convex or disc-like. Involucrellum not present, but the exposed part of the upper wall strongly thickened, composed of multiple layers of dark brown very thick-walled irregularly angular cells, sometimes occluded with melanized material, unchanged or darkening slightly in K. Interascal tissue of irregular frequently branched very thin-walled short-celled pseudoparaphyses 2-2.5 µm diam. with cells mostly 7-10 µm in length, sometimes breaking down at full maturity. Asci in a basal fascicle, 72-81 × 22-29 μm, obclavate with the upper part ± attenuated, almost sessile, thick-walled and fissitunicate, with an elongate apical channel that broadens above but no well-defined ocular chamber, not blueing in iodine, the cytoplasm with a dextrinoid reaction, 8-spored. Ascospores arranged biseriately, 19-20.5 (-22) x 5-5.6.5 µm, cylindric-ellipsoidal, with a slightly constricted ± median septum, the upper cell only slightly broader than the lower, hyaline, smooth, thin-walled, with a gelatinous sheath ca 1 µm thick; overmature spores brown, finely rugulose, sometimes thinly 3-septate.