Lichens marins

Alyxoria xerica (Torrente & Egea) Van Haluwyn & Cl. Roux =Opegrapha xerica Torrente & Egea

Opegrapha xerica Torrente & Egea

Description

Thallus very thin, slightly visible pale, glaucous-white, pale greyish, pale greenish-gray, pale greenish a little yellowish or these colorations mixed on the same thallus depending on the orientation. Apothecia in simple lirelles of 0.5-1.5 x 0.2-0.5 mm; very prominent, black, rarely powdered with gray-greenish, slit opening progressively in particular towards the center of the lirelle. Olive-green epithecium in KOH. Utriform asci with 8 spores. Colorless, shuttle-shaped spores, with sometimes asymmetrical ends (one wider and more rounded than the other), 3-4 (5-6) times septate, 14-20 x 4-6 µm according to the literature; 14-20 (22) x 4-5 µm according to our measurements. Black pycnidia, bacilliform pycnidiospores, 4-6 x 1-1.2 µm. C-, KC-, K-, P-. Rare (or going unnoticed) and very localized species, coming in the oceanic forests of Brittany and the South of Great Britain, on the bark of deciduous or coniferous trees: Quercus, Taxus, Cupressus.

Alyxoria varia is very similar but differs by its larger spores: 20-30 x 3-5 µm and its chocolate-brown epithecium in KOH.

N.B. Species taken here in the sense of the British authors but this taxon is probably different from the type species due to the difference in habitat and should probably be renamed.