Flora of New Zealand Series

Holotype: New Zealand. Stewart I., lower Kopeka River. On Coprosma foetidissima roots on rata in riverine rata-kamahi-totara-miro forest, c. 10 m, 12 February, 1980. C.D. Meurk, CHR 375960!

Thallus foliose-lobate, rather loosely attached centrally, margins ± free, to 15 mm wide. Lobes linear-elongate to ± rounded, 1 cm wide and 5 cm long, branching ± dichotomous, margins entire, slightly thickened, crenate at apices, sinuses between lobes rounded. Upper surface bright lettuce-green when wet, olivaceous-glaucous when dry, deeply and regularly reticulate-faveolate, connecting ridges prominent, lacunae deep, smooth, glabrous, without soredia, isidia, maculae or pseudocyphellae. Medulla white. Photobiont green. Lower surface pale yellowish-buff or ± whitish, conspicuously bullate, glabrous at margins, with short, soft, pale tomentum centrally. Pseudocyphellae white, punctate, small, scattered, rather indistinct. Apothecia sparse to occasional or frequent, scattered or contiguous, sessile or subpedicellate, marginal, disc 1-4 mm diam., black, smooth, matt, epruinose, margins thick, entire or subcrenulate, concolorous with thallus or distinctly yellowish or pale, thalline exciple smooth, shining, or slightly whitish or brownish, pubescent, concolorous with thallus. Ascospores biseriate, brown, polaribilocular (18.7-)22.1-25.5 × 6.8-8.3 µm, septum 1.5-2 µm thick. Chemistry: Cortex C+ red, methyl gyrophorate, tenuiorin, gyrophoric acid (±), methyl lecanorate (tr.), two unidentified depsidones, hopane-6α, 7β,22-triol, norstictic (tr.), stictic and constictic acids.

N: Hawke's Bay (Urewera National Park). S: Nelson, Westland to Fiordland. St: On twigs of trees and shrubs in moderate shade in damp, humid habitats. Mainly lowland in wetter areas.

Endemic

First collected by G. Einar and Greta Du Rietz from bark of Dacrydium cupressinum in mixed rain forest on Seymour I., Doubtful Sound in 1927. P. durietzii is characterised by the rounded, deeply faveolate lobes, black laminal apothecia and the pale, bullate, lower surface with scattered, punctate white pseudocyphellae. It is related to P. hookeri but distinguished by the green photobiont. These two species can form photosymbiodemes (Dr T.G.A. Green and Dr A.L. Wilkins, pers. comm.).