Cresponea premnea (Ach.) Egea & Torrente var. premnea

    Thallus crustose, smooth, thin, sometimes  evanescent or hardly visible, or slightly cracked,  pale grey-green, pale greyish, pale greenish, prothallus absent or inconspicuous, thin and blackish. Apothecia scattered all over the thallus, more or less regular, 1-2 mm diam.,  disc flat, hardly ever a little convex, black, sometimes pale greyish-pruinose at first or grey-green, true exciple distinct, rather thick, persistent, sometimes slightly crenulate or wavy, black. Asci in club of 65-70 x 13-15 µm according to our measurements. Cylindrical or shuttle spores with slightly pointed ends, sometimes slightly curved, (4)-5-6-septate, 18-25 x 5-7 µm according to the literature, 20-25 (30) x 4-5 (6) µm according to our measurements. Pycnidia mostly arranged in lines or groups, black. Photobiont: Trentepohlia. Chemical spot tests negative. Rather rare, on bark of old deciduous trees notably oaks (Quercus) in ancient rain forests. See  Cresponea premnea var. saxicola  that differs only by its habitat: vertical shaded walls of mossy siliceous rocks in old oceanic forests.