Fuscidea cyathoides (Ach.) V. Wirth & Vezda var. cyathoides
Thallus crustose, very variable in thickness and color, being able to form mosaics on large surfaces, smooth to rough, rimose, finely cracked like a faience, areolated, areoles irregular up to 0.5-0.6 mm per side, a little convex, greyish to brown tinges, brownish, celadon green to brown tinges (worn out specimen), greyish brown, these colors often being accompanied by glaucous tinges in humid weather, hypothallus sometimes zoned, brown-black, black, clearly visible including between the areolas and at the margin of the thallus. Apothecia more or less abundant sessile, 1-1.5 mm in diameter, disc flat then a little convex, dark brown to blackish, thin margin paler, strongly sinuous to lobed so well developed but sometimes not persistent. 8-spore asci of 55-80 x 15-20 µm according to our own measurements. Colorless spores so young but sometimes brown when mature, simple, often bean-shaped (be careful in this case they can under the microscope give the illusion of being 1-septate !), 9-13 x 4.5 -6 µm according to the literature and 10-13 x 5-7 µm according to our own measurements. Pycnidia frequent, immersed, brown. Photobiont: trebouxioid. Medulla: C-, P + red to reddish, K + dirty yellow. Species not especially maritime but with oceanic trends and therefore frequent in our prospecting region where it sometimes forms large mosaics on siliceous rocks but can also occur on stones. This species is extraordinarily variable and may be collective, we classically distinguish:
Fucidea cyathoides var. sorediata (H. Magn.) Poelt which has rounded yellowish-brown to greenish-gray soralia.
Fuscidea cyathoides var. corticola which grows in the mountains on the bark, in particular of Fagus.
And also many forms or ecoforms see for example: Fuscidea cyathoides forma which comes on rocks subjected to sea water projections.