Psoroma melanizum Zahlbr.
Holotype: New Zealand. Otago, Boyd's Bush near Dunedin, on schist rock. J.S. Thomson ZA 74, W.
Thallus squamulose, closely attached, in compact rosettes, often confluent in mosaics, 1-3 cm diam., bordered by a short, black, byssoid prothallus, 1-2 mm wide. Squamules minute, 0.2-1.0 mm diam., round to irregular, concave to plane to subconvex, margins entire, slightly thickened, often secondarily lobulate and dispersed at margins, coalescing, imbricate centrally, forming a diffract-areolate crust, prothallus visible between areolae, yellowish to pale whitish at margins, whole thallus superficially blackened, smooth to coriaceous, shining, waxy, epruinose. Cephalodia frequent, scattered, marginal on squamules, occasionally laminal or on hyphae of prothallus, ± rosette-shaped, dark purplish-grey, rising above squamules, wrinkled-plicate, smooth to slightly granular. Apothecia sessile, frequent centrally, rarely marginal, round to irregular, 0.5-1.5 mm diam., disc brown-black, plane to subconcave, matt, epruinose, margins thin, pale or concolorous with thallus, crenulate. Ascospores ellipsoid to subglobose, 12 µm diam., or smaller, 4-6 × 3 µm.
S: Coastal in eastern localities from Banks Peninsula southwards. St: A: Mainly coastal on rock.
Endemic
