Flora of New Zealand Series

Holotype: New Zealand. Nelson, Lake Rotoiti, Peninsula, on Leptospermum ericoides. D.J. Galloway, 29 February, 1980, CHR 343279! Isotype in BM!

Thallus orbicular, rosette-forming to spreading, 6-10(-16) cm wide, loosely attached, lobes short, rounded, 0.3-0.8 mm broad, imbricate or contiguous, margins entire, sinuous, shallowly incised, often subascendent, densely white- tomentose. Upper surface dark, livid, leaden-grey when wet, pale brownish- grey or pinkish-fawn when dry, ± uniformly thickly tomentose, tomentum long, white, silky, cortex below tomentum, smooth, undulate, uneven, shining, never scabrid. Medulla white. Photobiont blue-green. Lower surface pale brownish or whitish at margins, dark brown centrally, irregularly ridged or wrinkled-faveolate towards margins, ± uniformly tomentose, tomentum thick, whitish, silky, uneven, often developing in long, tufted fascicles towards margins. Pseudocyphellae yellow, tiny, 0.1-0.3 mm diam., scattered or frequent, sunk in tomentum. Apothecia not seen. Pycnidia not seen. Chemistry: Tenuiorin, methyl gyrophorate (±), methyl lecanorate, pulvinic dilactone, pulvinic acid, calycin, norstictic and stictic acid and constictic acids, hopane-15α-22-diol, hopane-6α,7β,22-triol.

N: Hawke's Bay (Kuripapango). S: NW Nelson. Apparently restricted to ± subalpine habitats on Leptospermum ericoides, L. scoparium and Olearia avicennifolia in successional vegetation. Tolerant of moderate shade in habitats of high rainfall and humidity.

Endemic

P. margaretae is related to P. pubescens and the two species form photosymbiodemes [Renner and Galloway loc. cit. ]. It differs from P. pubescens in the shorter, rounded, more imbricate lobes, the upper surface is not visibly faveolate or even markedly ridged, the surface of the lobes is evenly tomentose and the colour of the upper surface is a livid, leaden grey-brown. The species is discussed in detail by Renner and Galloway ( loc. cit. ).