Flora of New Zealand Series

≡Psoroma xanthomelanum Nyl., Syn. meth. lich. 2: 26 (1869).

≡Lecanora xanthomelana (Nyl.) Nyl. Compt. Rend. Hebd. Séanc. Paris, sér. D, 83: 89 (1876).

Lectotype: New Zealand. Wellington, Ruahine Ra., on Nothofagus bark, W. Colenso 4546 – BM [fide Galloway (1985a: 482)]. Isolectotypes – H-NYL 3082, WELT.

Description : Flora (1985: 482 – as Psoroma xanthomelanum).

Chemistry : Pd+ orange; containing pannarin.

N: South Auckland (Waipakihi Valley), Wellington (Ruahine Ra., Tararua Ra.). S: Nelson (Cobb Valley, West Bay, Lake Rotoiti), Canterbury (Margaret's Tarn Arthur's Pass), Southland (Borland Saddle). St: (Port Pegasus). A: (Enderby I.). C: (Mt Honey, Mowbray Hill). Primarily a species of Nothofagus forest and on twigs of understorey shrubs. On mossy peat and in rock crevices in fellfield in subantarctic habitats.

Endemic

Illustrations : Malcolm & Galloway (1997: 39, 108); Malcolm & Malcolm (2000: 18) – as Psoroma xanthomelanum.

Pannaria xanthomelana is characterised by: the corticolous (rarely terricolous) habit; the lobate–foliose thallus attached by a thick, black prothallus of entangled, black, simple to squarrose rhizines; flat lobes, 2–4 mm wide, ±dichotomously branched at apices which are sometimes lobulate, white-pubescent to blackened and with projecting, black prothallus; a greenish grey to mustard-yellow, glossy or waxy upper surface; conspicuous placodioid-lobed, bright-blue cephalodia developed marginally and laminally; laminal and marginal apothecia, clustered in conglomerate groups, 1–3 mm diam., the discs, pale to dark red-brown or blackened, faintly white-pruinose, often perforate centrally, and/or with concentric ridges or lobules of thalline tissue; subglobose ascospores, 11–16 μm diam.; and a chemistry containing pannarin. It has a green alga as major photobiont.