Psora decipiens (Hedw.) Hoffm.
Lichen decipiens Hedwig, Descr. adumbr. Musc. Frond. 2: 7 (1789).
Thallus squamulose, spreading, terricolous. Squamules 3-6 mm diam., peltate, clustered to ± scattered, upper surface salmon-pink to chestnut-brown, often copiously white-pruinose, margins entire, subcrenate, white. Apothecia marginal, black, 1-1.5 mm diam., convex, immarginate. Hypothecium pale brown. Asci clavate, 60-70 × 12-15 µm. Ascospores ellipsoid, 12-17 × 5.5-7.5 µm. Chemistry: Medulla K+ yellow, C-, KC-, Pd+ yellow. Norstictic acid.
S: Canterbury (Weka Pass, Castle Hill, Flock Hill, Ashburton Gorge near Mt Somers), Otago (Hampden), Southland (Clifden). On limestone soils, often in drainage cracks in limestone or scattered on soils near limestone outcrops.
Cosmopolitan
P. decipiens is characteristic of limestone areas, the thick, peltate, clustered squamules with the pinkish-brown upper surface, ± white-pruinose, being especially characteristic.
