Caloplaca saxicola (Hoffm.) Nordin
Psora saxicola Hoffm., Descr. adumbr. Pl. Lich. (3): 82 (1790).
Thallus squamulose, radiate-plicate, effigurate, rosette-forming 1-3(-5) cm diam., yellow, ochraceous or orange, rarely brown-red, distinctly lobate, K+ purple, saxicolous. Lobes convex, contiguous, 0.3-0.5 mm long and 0.25-1.5 mm wide, often scarcely longer than broad, or palmate, strongly white pruinose, pruina coarse, ± areolate-diffract centrally. Apothecia clustered centrally often obscuring thallus, numerous, to 1 mm diam., plane to convex, disc matt or slightly roughened, margins entire or minutely crenulate or somewhat granular, concolorous with disc or paler, persistent or occluded with age. Ascospores ellipsoid or oblong-ellipsoid with rounded apices, 2-locular, 9-16 × 4.5-7 µm, septum ⅓ to ½ length of spore. Chemistry: Emodin, parietin, xanthorin, fallacinal.
S: Canterbury (Weka Pass, Castle Hill, Mt Somers), Otago (Maheno), Southland (Clifden). On limestone rocks, often very common, imparting a characteristic orange-yellow colour to the rocks.
Cosmopolitan
Associated with C. decipiens (rarely), C. citrina, Diplotomma alboatrum. Formerly recorded as C. murorum.
