Cyphelium tigillare (Ach.) Ach.

        Thallus crustose which can reach 10 cm at its greatest length, more or less immersed in its substrate, strongly warty, bright and bright green-yellow (almost "fluo") if wet, more grayish-yellow or greenish-yellow if dry. Very numerous apothecia at the top of the warts (1 per wart), deeply immersed in the thallus (like a tooth), 0.4-0.7 mm in diameter, flat disc, brown-black, blackish, black, thin margin, concolorous to the thallus. Spores broadly elliptical, 1-septate with a constriction at the septum (in a ball of wool), brown-black, 17-21 x 9-11 µm. Abundant pycnidia. Photobiont: trebouxioid. C-, K-, KC-, P-. Rare mountain species growing on bare wood, generally conifer.

N.B. Cyphelium notarisii is very similar and is distinguished only by its spores which become submuriform.