Flora of New Zealand Series

Parmelia dilatata Vainio, Acta Soc. Faun. Fl. fenn. 7 (7): 33 (1890).

Thallus lobate, orbicular to spreading, large, 8-12 cm diam., loosely to closely attached, corticolous. Lobes rounded, undulate, 5-10 mm wide, margins entire, thin, slightly sinuous, ciliate, cilia to 1.5 mm, slender, numerous. Upper surface pale greenish-grey, smooth, matt, not shining or pruinose, very faintly maculate (×10 lens) at margins, becoming reticulate-cracked centrally, sorediate. Soralia marginal, short, linear, becoming convolute or slightly hooded on small, incised marginal laciniae, never recurved, soredia fine, granular, greyish-white, not becoming blackened. Lower surface smooth, black, with a wide, pale, naked marginal zone. Rhizines sparse, central, simple, black. Apothecia pedicellate, disc brown, to 3 mm diam., imperforate, margins entire, often sorediate, thalline exciple smooth and faintly maculate. Ascospores 18-22 × 8-10 µm. Chemistry: Cortex K+ yellow; medulla K-, C-, KC-, Pd+ red. Protocetraric acid and atranorin, occasionally usnic acid (tr.).

N: North Auckland to King Country. S: Nelson (St Arnaud). Still very much undercollected and poorly known. It is most common in northern coastal habitats where it can be a conspicuous epiphyte of trees and shrubs.

Pantropical

P. dilatatum may be confused with P. cristiferum and the two plants occupy similar habitats. P. dilatatum has a different chemistry, long marginal cilia and more laciniate margins with coarse irregular soralia.