Flora of New Zealand Series

P. araneosum (Church. Bab.) Nyl., Syn. Meth. Lich. 2: 23 (1863).

Pannaria rubiginosa var. araneosa Church. Bab., Fl. N.Z. 2: 289 (1855).

Psoroma subpruinosum Nyl. in J.D. Hook., Handbk N.Z. Fl.: 574 (1867).

Lectotype: New Zealand. Sine loco (prob. Bay of Islands). J.D. Hooker, BM!

P. subpruinosum. Lectotype: New Zealand. Sine loco (?Waiheke I.). Milne 41, 1853 (H.M.S. Herald), BM!

Thallus large, rosette-forming to spreading, loosely to closely attached, lobate-foliose, free at margins, without a prothallus, 5-12(-20) cm diam. Lobes broad, 5-20 mm wide, coriaceous, margins rounded, sinuous often crisped, ascending, overlapping, conspicuously thickened. Upper surface uneven, matt centrally, coarsely scabrid near margins and regularly marginally tomentose, tomentum white, arachnoid, pubescent, plant bright green when wet, pale greenish-grey or pale greenish-fawn when dry. Medulla white. Lower surface whitish, naked or very finely tomentose, striate, with occasional tufts of pale buff, squarrose rhizines centrally. Cephalodia frequent to moderate, small, globose, ± granular to subplacodioid, 1.3 mm diam., pale whitish-grey, laminal, densely wrinkled-plicate. Apothecia sessile, laminal, often crowded centrally 1-5 mm diam., margins concolorous with thallus, thick, crenulate-striate, disc plane or subconcave, chestnut-brown to dark red-brown, smooth, matt, epruinose, not gyrose-contorted, without fissures or thalline lobules, thalline exciple wrinkled-verrucose. Ascospores ellipsoid, 12-16 × 8-9 µm.

N: North Auckland (Three Kings Is) to Wellington, most common in coastal localities north of Auckland. S: West Coast throughout, Banks Peninsula to Southland (Greenhills) on east coast. St: Mainly lowland and coastal, on bark of trees and shrubs or on rocks in well-lit situations.

Endemic

One of the largest species of Psoroma and characterised by the tomentose lobe margins.

Specimens labelled Psoroma subpruinosum Nyl., collected by Charles Knight ("Super corticeum arborum prope Wellington in Nova Zelandia") were distributed by Lojka in his Lichenotheca Universalis Fasc. III: 123 (1886).