Distribution: N - Emil (Boqueras & al. 1999, Fariselli & al. 2020). C - Sar. S - Camp (Brunialti & al. 2013, Ravera & Brunialti 2013).
Description: Thallus crustose. episubstratic, sorediate, continuous to usually areolate-verrucose or bullate-tuberculate, grey-white, grey or grey-brown. sometimes delimited by a whitish prothallus. Soralia ronded to irregular, mostly arising at the tip of warts, with a more brown hue than thallus, at first well-delimited and concave with a distinct, raised thalline rim, finally convex and sometimes confluent, bearing granular soredia. Apothecia very rare, lecanorine, up to 3 mm across, with a concave to flat, brown, faintly pruinose disc, a distinct parathecial ring, and a thick, raised thalline margin. Proper exciple well-developed; epithecium pale brown; hymenium colourless, c. 300 µm high; hypothecium pale yellowish brown. Asci 4-6-spored, with thick, amyloid walls, Pertusaria-type. Ascospores 1-celled, hyaline, ellipsoid, 50-69 x 25-35 µm. Spot tests: thallus and apothecial margin K- C+ yellow, KC+ yellow, P-; thalline medulla C-; epithecium, soredia, and upper part of proper exciple C+ red. Chemistry: cortex with variolaric acid; epithecium, soredia, and upper part of proper exciple with gyrophoric (major) and lecanoric (minor) acids.
Note: a poorly understood, rarely collected lichen, which badly deserves further study. Indicator values are tentative. The record from Venezia Giulia reported by Nimis (1993: 510) was due to a misidentification. The species is included in the Italian red list of epiphytic lichens as “Data Deficient” (Nascimbene & al. 2013c).
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)