Thallus subcuticular, effigurate, circular, (1-)2-4 mm diam., rarely to 6 mm diam., marginal lobes very short, rounded, 0.1-0.3 mm broad, distinctly convex, ± uneven to rugose, pale bluish-green to almost white (pure white when moribund) usually with numerous, shining, black points (pores of pycnidia), without a prothallus. Perithecia 1-10 per thallus rosette, 0.25-0.4 mm diam., convex, immersed in thallus at base, exposed part convex, black, shining, ostiole visible as a grey or white point. Asci narrowly obclavate, 45-70 × 10-14 µm. Ascospores 1-septate, biseriate, broadly fusiform but with one cell larger than the other, ends acute, strongly constricted at septum, 17-25 × 4-7 µm. Pycnidia 0.05-0.1 mm diam., ± globose, ± immersed in thallus, upper wall exposed, black, shining. Macroconidia 1-septate, bacillar, 15-18 × 3-4 µm.