Flora of New Zealand Series

Lichen saxatilis L., Sp. Pl.: 1142 (1753).

Thallus orbicular, closely attached, 4-10 cm diam., corticolous or saxicolous. Lobes rather narrow (4-12 mm wide), elongate, (to 30 mm long), with slightly broadened, incised apices, margins entire, ± sinuous. Upper surface faveolate, shining towards margins, pale greyish or greenish, pseudocyphellae laminal forming a prominent, ridged reticulum of white lines, isidiate. Isidia coarse, blackened at apices, granular to elongate-branched, occurring mainly on ridges of pseudocyphellae reticulum and sometimes completely covering the whole upper surface. Lower surface black or dark brown, paler at margins, densely rhizinate. Rhizines black, simple or sparingly branched, commonly extending beyond margins, marginal zone always rhizinate or papillate. Apothecia occasional to rare, subpedicellate, to 8 mm diam., disc concave to plane, dark brown, matt or slightly shining, centrally perforate, margins thin, crenate, isidiate, concolorous with thallus. Ascospores ellipsoid, 14-18 × 7-9 µm. Chemistry: Cortex K+ yellow; medulla K+ yellow → red, C-, KC+ red, Pd+ orange. Salazinic and lobaric acids and atranorin.

S: Central Otago (Old Man Ra., Alexandra), and Dunedin.

Cosmopolitan

P. saxatilis is rare in New Zealand. It resembles P. pseudotenuirima; the distinctions between these two taxa are detailed under the latter species. The taxon P. saxatilis var. aizonii Delise in Duby, recorded by Zahlbruckner [ Denkschr. Akad. Wiss. Wien math.-naturwiss. Kl. 104: 355 (1941)] is referable to Xanthoparmelia australasica [Galloway N.Z. J. Bot. 18: 531 (1981)].