Bacidina phacodes (Körb.) Vezda

     Thallus crustose, rather thin, uneven, pale greyish, whitish, greenish-whitish when fresh and moist, pale brownish-greenish when dry, sometimes with free-living green algae. Apothecia sessile, 0.2-0.5 mm diam., cup-shaped at first then quickly convexe and subglobulose, more or less bumpy and almost muriform, translucent whitish, cream-whitish at the beginning turning light beige, orange-pinky when mature, thick margin, same colour, visible only when young. Ascopores needle-shaped, colourless, 3-7-septate, 25-45 x 1.5-2 µm. Photobiont: chlorococcoid. No reaction to chemical spot test. Species not common, growing on bark at the base of deciduous trees (Acer ...), either on stand-alone line trees or at the edge of woods and humid forests.

_See Mycobilimbia pilularis with more coloured apothecia, granular thallus and living in a different habitat.