Forum Flora Germanica

Thallus and apothecial margin UV+ bright pink Polyozosia antiqua (J.R. Laundon) S.Y. Kondr., Lőkös & Farkas
Thallus crustose, granular-warted to inconspicuous and hardly evident, pale grey to cream-coloured, without a distinct prothallus. Apothecia lecanorine, sessile, 0.3-0.8(-1) mm across, usually crowded in small clusters, round or irregular in outline due to mutual compression, with a flat to slightly convex, pale brown to pale grey-brown, sometimes pruinose disc and a thick, smooth, often crenulate, white-pruinose, finally often excluded thalline margin. Thalline exciple corticate, rich in algae, with a few crystals; epithecium brownish yellow, 10-13 µm high; hymenium colourless, 45-60 µm high; paraphyses sparingly branched, 1-2 µm thick at mid-level, the apical cells somewhat wider but not markedly swollen; hypothecium colourless. Asci 8-spored, elongate-clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a K/I+ blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, (8-)11-13(-15) x 4-7 µm. Pycnidia rare. Conidia 10–15 × c. 0.5 µm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C- or C+ pale yellow, KC+ pale yellow, P-; apothecial margin K+ yellow, C+ and KC+ orange-brown, UV+ bright pink: apothecial disc C+ yellow-orange. Chemistry: xanthones, mainly concentrated in the apothecial margin. Note: on steeply inclined surfaces of basic siliceous rocks (especially basalt), sometimes on calciferous rocks. For further details see Laundon (2010).