Punctelia rudecta auct. non (Ach.) Krog
Parmelia rudecta Ach., Syn. Lich.: 197 (1814).
Cetraria corallophora Müll. Arg., Bull. Soc. r. Bot. Belg. 31: 26 (1892).
Cetraria corallophora. Lectotype: New Zealand. Sine loco. W. Stephenson, 1843-4, BM!
Parmelia rutidota var. vestita. Type: New Zealand. Otago, Mt. Watkin, J.S. Thomson ZA 210, W - not seen.
Thallus spreading, closely attached 4-8(-20) cm diam., corticolous or saxicolous. Lobes rounded, crenate or regularly incised, dissected, somewhat crowded, margins sinuous, black, shining, isidiate. Upper surface smooth, shining, glossy, wrinkled, becoming ± faveolate at or near margins, wrinkled- ridged centrally, pale greenish-white or greenish-grey or pale bluish-grey, often brownish at margins, pseudocyphellae small, punctiform, mainly marginal, not becoming sorediate. Isidia flattened, lobate-squamiform, rarely terete and simple, becoming strongly dorsiventral, marginal in young lobes, spreading densely over surface of older lobes. Lower surface uniform pale buff or tan with a smooth, pale, naked marginal zone. Rhizines central, simple, pale, long, often densely developed. Apothecia occasional, pedicellate, to 10 mm diam., disc dark red-brown, matt, smooth, imperforate, plane to deeply concave, thalline exciple concolorous with thallus, pseudocyphellate and isidiate. Spores subglobose to broadly ellipsoid, 15-20 × 10-12 µm. Chemistry: Cortex K+ yellow; medulla K-, C+ red, KC+ red, Pd-. Lecanoric acid and atranorin.
N: Hawke's Bay (Hastings) and Akitio. S: Banks Peninsula to Invercargill, mainly coastal and lowland. Inland east of the Main Divide, Peel Forest, Hunter, Matukituki and Dart Valleys. A: (Enderby I.).
Cosmopolitan
P. rudecta is characterised by the abundant lobular, squamiform isidia, the uniformly pale lower surface and the presence of lecanoric acid in the medulla. It is distinguished from P. subrudecta by the absence of soralia. It colonises a variety of substrates, lignum (fenceposts etc), bark and rocks.
