Parmotrema grayanum (Hue) Hale
Parmelia grayana Hue, Nouv. Archs Mus. Hist. nat. Paris, sér. 5, 1: 184 (1899).
Thallus orbicular, closely attached, to 5 cm diam., saxicolous. Lobes rounded, 5-12 mm wide, crowded, margins crenate, often ascending, ciliate, cilia sparse to conspicuous, 0.5-1.5 mm long, rather coarse. Upper surface matt, coriaceous, greenish-grey, often pruinose at lobe margins and becoming irregularly cracked, sorediate. Soralia marginal, linear to subglobose, soredia coarse, granular, white at first, becoming dark greyish-black. Lower surface black, with a naked, brown, marginal zone. Rhizines black, simple. Apothecia not seen. Chemistry: Cortex K+ yellow; medulla K-, C-, KC-, Pd-. Caperatic acid and atranorin.
N: North Auckland (Three Kings Is to Russell) on coastal rocks and on bark of Avicennia resinifera. Still poorly collected.
Pantropical
P. grayanum is distinguished from P. reticulatum and P. perlatum by chemical differences and the coriaceous upper surface which is distinctly white pruinose and not maculate or cracked in young lobes.
