Thelopsis corticola (Coppins & P. James) Sanderson & Ertz = Opegrapha corticola Coppins & P. James p.p.

       Thallus fairly thin crustose, continuous and without prothallus, gray-greenish, greenish in shade, yellow-ochre, gray-brownish, pale brownish in light, covered with punctate soralia 2-3 mm in diameter, ocher-greenish, gray-brownish, yellowish, ochraceous, becoming confluent and finally forming a continuous crust with finely grainy ochraceous soredia. Very rare perithecia (but it is sometimes possible to find their trace in the form of small cavities, especially at the periphery of the thallus) immersed in the thallus and only showing their top, 0.4-0.6 mm in diameter, reddish-brown. Cylindrical asci containing many spores (up to a hundred), 100-120 x 12-15 µm according to our measurements. Hyaline spores, oblong with rounded ends, (2)-3-septate, 7.5-13 x 3-5 µm according to literature, 8-13 x 4-5 µm according to our measurements. Photobiont: Trentepohlia. C-, K-, KC-, P-. Rare species coming to the base receiving rain from trees in humid oceanic forests (often on Cupressus).

N.B. Species very similar to Thelopsis rubella but this last species differs by its DNA, its larger spores and the absence of soredia.

Watch out for Porina multipuncta with bright orange soralia, coming into crevices at the base of deciduous trunks but also on rocks, and also Francisrosea bicolor with non-continuous, bicolored soralia: orange above, yellow below.

Zwackhia sorediifera is C + reddish pink (sometimes weak!).