Opegrapha varia Pers.
Opegrapha lichenoides Pers.
Thallus crustose, very thin and inconspicuous, more or less smooth, pale grey, pale grey-brownish, sometimes tinged green. Apothecia lirelliform, rather long, 1-3 x 0.2-0.5 mm, minutely above the thallus level, 0.08-0.12 mm tall, simple, seldom branched or stellate, blackish, disc slit-shaped, more or less opened, greyish. Ascospores fusiform with sligthly rounded ends, brown-reddish when marure, 20-37 x 6-9 µm. Pycnidia grey, conidia bacilliform. Chemical spot tests negative. Highly variable. Several taxa growing on alkaline barks of deciduous trees have been described.*