Placopsis trachyderma (Kremp.) P.James
Lecanora trachyderma Krempelh., Verhandl. zool.-bot. Ges. Wien 26: 451 (1877).
Placopsis alphoplacoides Lamb, Lilloa 13: 234 (1947).
Holotype: New Zealand. Sine loco. Charles Knight, M 123-80/8!
Thallus determinate, effigurate spreading, to 10 cm diam., saxicolous and terricolous, often with a black marginal prothallus. Marginal lobes swollen, discrete, separated by narrow cracks or becoming confluent, closely to loosely attached. Upper surface creamish to grey-white or pinkish-brown, smooth, matt, wrinkled-areolate centrally, areolae small, warted, 0.3-1 mm diam., becoming continuous, wrinkled or folded, soredia absent, isidiate ( var. clavifera). Isidia central, sparse to numerous, wrinkled-warted, terete, simple to branched, to 4 mm tall. Cephalodia sparse to numerous, irregularly pulvinate or rounded-cerebriform, to 3 mm diam., pale flesh-coloured, matt, epruinose. Apothecia numerous, scattered, subpedicellate, 2-3 mm diam., thalline margins prominent, entire, subcrenulate, often white-pruinose, disc plane to subconvex, pinkish-brown to brown-black, wrinkled often pruinose. Hymenium 130-140(-160) µm tall, pale brown-yellow at apices. Hypothecium colourless. Paraphyses slightly thickened at apices. Ascospores biseriate, fusiform, apices rounded, (17-)18-21(-25) × (5-)5.5-6.5 µm. Chemistry: Cortex K-, C+ red; medulla K-, C+ red, KC+ red, Pd-.
N: Mt Ruapehu, Tararua Ra. S: Nelson (Maruia Valley), Canterbury (Arthur's Pass, Lake Tekapo), Westland (Buller River, Otira Gorge), Otago (Hopkins Valley, Huxley River, Matukituki River, Dart River, Pulpit Rock, Silver Peaks), Southland (Dusky Sound, Fiordland). Widely distributed on rocks and soil on river banks, stream beds and glacial moraines, alpine or subalpine.
Australasian
