Thallus thin, effuse, mauve-grey to whitish grey. Anamorph: conidiomata pycnidia, 200-300 µm diam., numerous and evenly scattered, cylindrical, knob-like, with white-pruinose apices. Conidiomatal walls 25-50 μm thick, dark brown in water mount, green-black in K. Conidiogenous cells 8-12 × 2-2.5 μm, cylindrical to slightly tapered, proliferating percurrently with conspicuous annellations. Conidia 12-17 × 2-3 μm, cylindrical to cylindric-fusiform, sometimes slightly curved, hyaline, aseptate, thin-walled, usually multiguttulate, without an epispore, gelatinous sheath or appendages. Teleomorph: ascomata apothecia (not always present), 0.7-2 mm diam., circular, sessile or appressed, thickly yellow-grey pruinose over a brown-black disc, which has a prominent, persistent proper margin. Asci clavate to cylindric-clavate, fissitunicate, the apex with a narrow, K/I± pale blue apical dome penetrated by a small ocular chamber that is sometimes surrounded by a small, K/I+ dark blue, ring-like zone, 8-spored. Ascospores 28-40 × 3-6 μm, fusiform to acicular, 3- (to 4-) septate, ± curved, hyaline, thin- and smooth-walled, without an epispore, gelatinous sheath or appendages. Chemistry: pycnidial pruina C+ red, K–; apothecial pruina and thallus C–, K–, KC–, Pd–; medulla UV+ yellow- or glaucous grey (lecanoric and schizopeltic acids, unknown UV-1 positive substances).