Description: Thallus crustose, thinly episubstratic, continuous, smooth to finely granulose, dark green or grey-green, sometimes evanescent. Apothecia biatorine, 0.1-0.4(-0.5) mm across, sessile, round, slightly constricted at base, with a concave to flat, whitish to cream-coloured disc (turning yellowish or pinkish in the herbarium) and a thin, smooth, persistent proper margin. Proper exciple well-developed, paraplectenchymatous, composed of globose to angular cells with an outer layer of weakly vertically oriented hyphae; hymenium colourless, 70-90 μm high, I+ blue, then rapidly dirty green and finally red-brown, K/I+ blue; paraphyses simple or sparingly branched in upper part, 1-2 µm thick at mid-level, the apical cells c. 4 µm wide; hypothecium colourless. Asci 8-spored, subcylindrical-clavate, with a blue outer coat and uniformly K/I+ blue apical dome, Catillaria-type. Ascospores 1-septate, hyaline, fusiform to ellipsoid, 9-13(-15) x 2-3.5(-4.5) μm. Pycnidia more or less immersed, hemispherical, 0.1-0.2 mm across, the wall colourless. Conidia oblong, 6-7(-8) x 1.8-2.8 µm, often constricted in the middle. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a probably holarctic lichen, most common on acid bark, both of conifers and of broad-leaved trees, below the subalpine belt; certainly widespread throughout the country, especially in non-heavily disturbed semi-natural areas with a humid climate.