Physcia tribacioides Nyl.
Thallus rather delicate, often rosette-forming, closely attached to 4 cm diam., corticolous. Lobes dichotomously to irregularly branched, often imbricate, 1-2.5 mm wide. Upper surface plane or ± convex, whitish-grey to pale greenish-grey, occasionally white-maculate, without pruina, sorediate. Soralia laminal, capitate to crateriform, soredia granular, rather coarse, white to pale greenish-white in shaded situations. Lower surface pale, rhizinate. Rhizines pale, sparse, short. Apothecia rare, central, sessile to subpedicellate, to 1 mm diam., disc dark brown, densely grey-pruinose, margins thick, entire, concolorous with thallus. Ascospores 18-21 × 7-9 µm. Chemistry: Cortex and medulla K+ yellow. Atranorin, leucotylin, zeorin and two unidentified compounds.
N: North Auckland (Pandora to Whangarei), South Auckland (Te Aroha and King Country). S: Canterbury (Banks Peninsula), Southland (Waihopai Reserve).
Cosmopolitan
From both bark and rocks; still very poorly collected. Material from shaded, ± eutrophic habitats in eastern Canterbury (Banks Peninsula) is rarely fertile and greenish-white in colour, whereas specimens from coastal shrubs (Avicennia) in North Auckland are white, ± rosette-shaped and often fertile. Recently, material of P. albata (F. Wils.) Hale, was identified by Dr Roland Moberg (Uppsala) from a collection made by J.K. Bartlett from East Cape. It is possible that some collections of P. tribacioides from New Zealand may be referable to P. albata, but further collections are necessary to establish this point unequivocally.
