Alyxoria ochrocheila (Nyl.) Ertz & Tehler
=Opegrapha ochrocheila Nyl.
Thallus crustose, very thin, smooth, evanescent, whitish, white-grey sometimes tinged green or brown, or as thin as the bark colour below is visible. Apothecia numerous, lirelliform, simple, straight or curved, seldom forked or stellate, 0.5-2 x 0.2-0.4 mm, black, typically with a brown-orange pruine around and along the slit, usually rather open. Ascospores narrowly ellipsoid or somewhat clavate, 3-septate, without perispore, 12-20 x 3-5 µm. C-, K+/- purple in orange tinged sections, Pd-; pruine brown-orange : K+ purple. Rare (or understated?) in our prospection area, on bark of deciduous trees in dark and humid woodlands. N.B. This species is rather easy to identify in the field when fresh, owing to its lirellae, powdery, ochre-red (this pruine is K+ purple, potentially extending to other thallus sections in favourable conditions). Old specimen, washed-out, may be compared to Alyxoria culmigena (Opegrapha herbarum) without reddish pruine and with larger ascospores.*