Flavoplaca limonia (Nimis & Poelt) Arup, Fröden & Sochting = Caloplaca limonia Nimis & Poelt

    Thallus crustose, granulose-squamulose, squamules 1-2.5 mm across and 0.1-0.5 mm thick, areolate-like, squamules covered with blastidia producing, when mature or by erosion, farinose soralia; bright yellow when moist, sections with blastidia cream yellow when dry, sections with soredia paler and typically farinose. Apothecia more or less numerous, 0.2-1.5 mm diam., disc concave or plane, bright orange, exciple apparently thick due to blastidia and/or soralia, concolourous to the thallus. Ascii 8-spored, 55-65 x 14-18 µm. Ascospores polarilocular, ovoid to broadly ellipsoid, 11-15 x 5-8 µm with a septum of 4-7 µm (12-15 x 4-7 µm according to our measures). K+ purple. Belongs to the group of Caloplaca citrina, grows in the supralittoral zone on calcarous rocks (often together with: Lecanora dispersa, Lecanora albescens, Physcia adscendens, Verrucaria macrostoma f. furfuracea, etc.).

N.B. This species is very close to Caloplaca britannica that would be conspecific. Also very close to Flavoplaca arcis of which the thallus margin is lobate and blastidiate. In addition the latter species grows mainly on old walls, notably on chapels near the seashore.*