Lichens marins

Alyxoria culmigena (Lib.) Ertz

=Opegrapha culmigena

Opegrapha culmigena Lib.

Opegrapha herbarum Mont.

Opegrapha varia var. herbarum

Opegrapha betulina Sm.

Description

Thallus crustose, 0.5-2 cm, thin, smooth and not sorediate, whitish, pale grayish-white if dry, yellowish-gray to greenish-gray, olive, olive-brown if moist, without hypothallus if alone. Apothecia in the form of protruding lirelles, simple and sinuous, rarely branched or star-shaped, 0.5-2 x 0.2-0.5 mm, shiny black but sometimes with powdery greenish spots, disc at the bottom of a slit. Hyaline spores, club-shaped, with a thin perispore, 3-septate, 18-26 x 5-7 µm according to the literature, 20-29 x 6-8 µm according to our measurements. Pycnidia rare, black. Photobiont: Trentepohlia. Chemical reactions negative. Species coming in the shade on the smooth bark of the shrubs, in particular the shrubs constituting the hedges of the gardens by the sea, sometimes on the herbaceous debris, the stubble, etc. This species seems common but it goes unnoticed, its preferential habitat being little explored... N.B. Appearance quite variable depending on the nature of the substrate. See Opegrapha ochrocheila with red-orange bloom and smaller spores.