Description: Thallus crustose, ecorticate, granular-verrucose, pale whitish grey to pale green, often with yellow-orange to rusty red patches which may extend over most of the thallus, rarely immersed. Apothecia rather frequent, on long stalks, pin-like, 0.4-2 mm tall, 5-15 times as long as width of stalk; stalk 70-150 µm diam., shiny, black, epruinose; capitulum broadly to narrowly obconical. True exciple well-developed, epruinose. Maezedium pale to dark brown, often with a yellow tinge. Asci formed in chains, disintegrating early, producing a mass of spores (maezedium) which accumulates on the surface of the apothecia. Ascospores 1-celled, dark brown, uni- to biseriate, globose, 5.5-7.5 μm diam., thick-walled, coarsely and irregularly fissured at maturity. Spot tests: thallus K-, C-, KC, P-, except the pigmented parts, which react K+ deep red; ascospore mass with a yellowish, K+ red pigment. Chemistry: a quinoid pigment.
Note: a cool-temperate to boreal-montane, circumboreal species found on acid bark, especially of very old oaks, Castanea and conifers, on faces protected from rain, sometimes on decorticated stumps and even charred wood, reported as tolerant of air pollution and expanding in northern Europe, but rare and bound to natural habitats throughout Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)