Thallus 5-10(-20) mm diam., continuous or at periphery dispersed into rounded patches of varying size connected by a thin prothallus, greyish-white to grey, sometimes with a greenish tinge, smooth, matt or subnitid, foliicolous. Apothecia strongly constricted at base, 0.3-0.8 mm diam., round or somewhat irregular at margins, scattered, disc black, epruinose, plane at first with a thin, black margin, becoming convex and immarginate. Hypothecium dark purplish- brown, 20-90 µm thick. Ascospores 2-4, rarely 6 or 8 per ascus, muriform with 15-30 transverse and 1-3 longitudinal septa, narrowly ellipsoid to almost cylindrical, 50-105 × 9-17 µm. Pycnidia scanty, often absent, sessile or with immersed bases, globose, 60-70 µm diam., bluish-black, scattered. Conidia simple, dumb-bell to flask-shaped, 5-6 × 1-1.5 µm.