Thallus yellowish or pale creamish grey, variablly developed; sometimes thick and distinctly verrucose, reduced to irregular coalescing areoles or inconspicuous (then only soralia visible). Soralia to 800 µm diam., round to elliptical in outline, bright yellow, greyish-yellow to bluish-yellow [hyaline in preserved specimens], dense or ± diffuse, discrete or coalescing; crateriform, flat or strongly convex. Soredia 20-40 µm diam. Thallus margin not well delimited.
Anamorph: conidiomata rare, sunken in the thallus, 100-120 x 90-100 µm, walls hyaline; conidia filiform, curved, hyaline, 15-19.5 x ca 0.5 µm [Brodo & Vänskä 1984].
Teleomorph: apothecia 600-900 (-1100) µm diam., at first ± flat but later usually strongly convex, sessile. Margin yellowish, thick, smooth or sorediate, becoming excluded. Discs brownish to black, shiny, occasionally pruinose when young. Epithecium brown, granulose, granules disappearing in KOH; hymenium 40-50 µm thick; hypothecium distinct, to 120 µm thick, with a thick algal layer below. True exciple not well differentiated. Paraphyses thick, septate, sometimes branched near the dark brown-pigmented apices. Asci Lecanora-type, broadly clavate to almost saccate when mature, 8-spored. Ascospores irregularly arranged, 10-10.5 x 4-4.5 µm [12-13.5 x 3 µm fide Sliwa & Wetmore 2000], somewhat irregular in shape but usually ellipsoidal or slightly cylindric-clavate, aseptate, hyaline, thick-walled, without a gelatinous sheath or appendages.
Chemistry: thallus and soralia C+ orange, K+ yellow, K/UV+ green, P- (usnic acid, zeorin, and thiophanic acid).
Not assessed, but likely to be rare and vulnerable to climate warming in our region.
Known from a single site on Whalsay (VC112 Shetland).
On a softwood plank embedded in grass above the shoreline.