Description: Thallus crustose, inconspicuous, thin to scurfy, pale green or grey. Apothecia scattered to aggregated, usually immersed, later sometimes becoming sessile, 0.2-0.7 mm across, with a pale yellow-brown to pale orange or finally dark brown, deeply concave, waxy disc and a smooth to radially cracked, cream-coloured, brownish or yellowish pink proper margin which is sometimes overrun by thallus. Proper exciple thick, colourless or pale brown in outer part; epithecium hardly differentiated from the hymenium; hymenium colourless, 90-115 µm high; paraphyses slightly longer than the asci, septate, capitate, the apical cells up to 3-4 µm wide; hypothecium colourless to pale yellow. Asci 8-spored, cylindrical to elongate-clavate, thin-walled, lacking an apical apparatus or tholus, K/I+ blue. Ascospores muriform (with 6 or more cells visible in optical view) with 4-9 transverse septa and 1-2 longitudinal septa, most septa perpendicular to each other, hyaline, fusiform, without conical tips, (14-)17-28(-31) x 5-9 µm. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a temperate lichen found on mature trees, mostly Acer and Fraxinus, but also on the slightly nutrient-enriched bark of more acid-barked trees such as oaks, in mild-humid areas; more common in the past, presently localised in clearings of ancient, open, humid deciduous forests.
Growth form: Crustose
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)
, Germany, Baden-Württemberg, Kreis Göppingen, Albrand, Bad Überkingen, auf dem Pfad zum Kahlenstein, 48°35.892'N, 9°48.493'E, 675 m, auf Esche beim Höhleneingang des Kahlensteins, Schumm, 02.07.2006
P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (38246) 2008.02.25
P.L. Nimis; Owner: Department of Life Sciences, University of Trieste