Flora of New Zealand Series

P. psilophylla (Müll. Arg.) D. Galloway et P. James, Lichenologist 12: 301 (1980).

Sticta psilophylla Müll. Arg. Bull. Soc. r. Bot. Belg. 31: 29 (1892).

Holotype [fide Galloway and James loc. cit., p. 301 (1980)]: New Zealand, Sine loco. Charles Knight, G!

Thallus ± linear-elongate, spreading, loosely attached, to 20 cm diam. Lobes linear-elongate to 6 mm wide, ± discrete, to contiguous, margins rather fragile, copiously incised, isidiate, ± ascending, becoming concave and ± canaliculate. Upper surface bright lettuce-green when wet, pale greenish-grey or fawn when dry, undulate, ± canaliculate, wrinkled to shallowly faveolate, matt or shining, marginally and then laminally isidiate. Isidia terete to somewhat flattened, simple, becoming coralloid-branched, fragile and easily abraded, leaving small, white pock-like depressions not to be confused with pseudocyphellae. Medulla white. Photobiont green. Lower surface pale pinkish-buff, whitish at margins, obscurely wrinkled-scrobiculate, bullate, glabrous, rarely very thinly and patchily tomentose centrally, tomentum white, silky, often lacking. Pseudocyphellae white, minute, inapparent, punctiform, fleck-like, numerous. Apothecia sparse, submarginal, 1.0-1.8 mm diam., subpedicellate, disc red-brown, matt or shining, concave to plane, margins denticulate-isidiate, thin, concolorous with thallus, thalline exciple wrinkled. Ascospores brown, fusiform, 1-3-septate, (23-)28-34(-42) × 7-11 µm. Chemistry: 7β-acetoxyhopan-22-ol, hopane-15α,22-diol, methylgyrophorate (tr.) and gyrophoric acid (C+ red).

N: Throughout, Three Kings Is to Wellington. S: Rather rare, northwest Nelson to Greymouth, Banks Peninsula and Green Hills (Southland). On trees and shrubs in lowland, coastal forest, best developed in northern, coastal habitats.

Australasian

P. psilophylla is distinguished by its glabrous, pale lower surface, green photobiont, white medulla, and the fragile marginal or laminal isidia. It is a fragile, brittle species and may be mistaken for P. episticta but that species has pseudocyphellae on the upper surface that are not derived from isidia, and is tomentose on the lower surface.