Flora of New Zealand Series

Holotype: New Zealand. Southland, Fiordland, Deep Cove, Doubtful Sound. On Coprosma propinqua, 4 March, 1927. G. Einar and Greta Du Rietz 2075:1, S!

Thallus forming regular or irregular, complete or partial rosettes or irregularly encircling twigs and then often fragmentary, loosely to closely attached, 3-5(-8) cm diam. Lobes few to numerous, 1-2 mm wide, often discrete at margins or intricately interwoven, zig-zag, often markedly contorted centrally, terminal lobes subdichotomously branched, margins notably sinuous-angular, not, or sparingly blackened, upper and lower surface of internal cavity white. Upper surface convex, occasionally where lobes are bunched forming ridges, glaucous or greyish, smooth, slightly glossy. Perforations numerous, rather regularly distributed, margins elevated and becoming sorediate, to 0.5 mm diam., in median line. Soralia mainly confined to and surrounding perforations, white, finely granular, rarely a few laminal and not associated with perforations. Apothecia rare, 2-8 mm diam., ± pedicellate often with ± crenulate and ± sorediate margins, disc brown, shining, subconcave to plane, epruinose, exciple slightly wrinkled, concolorous with thallus. Epithecium not granular. Asci 2-spored. Ascospores simple, oval to ovoid, 45-56 × 20-32 µm, wall 4-5 µm thick. Chemistry: Stictic, constictic, norstictic (tr.) and menegazziaic acids, atranorin (cortex ±), and accessory compounds, medulla K+ yellow → orange, C-, KC+ orange, Pd+ orange.

N: South of lat. 35°S. S: St: A: C: Ant: Throughout, coastal and inland, on trees, shrubs and fenceposts, s.l. to 1200 m.

Australasian

M. circumsorediata is a distinctive species in having sorediate perforations; soralia are rarely developed elsewhere on the thallus and are always few in number. M. subpertusa has a similar thallus but this species usually has a duller, more corrugate surface and the soralia are mostly not associated with the perforations. M. circumsorediata has a wide ecological amplitude being common in dry Leptospermum shrubland as well as damp, forested areas close to, and both east and west of, the Main Divide.