Xanthoparmelia isidiigera
≡Parmelia conspersa var. laxa f. isidiigera Müll.Arg., Flora 66: 48 (1883).
Description : Thallus adnate on rock, 6–10 cm diam. Lobes narrow, 1–2(–5) mm wide, irregular, imbricate or not, occasionally with narrower secondary lobes developed centrally. Upper surface yellow-green to blackish green with age, smooth, glossy near apices, emaculate, plane to subconvex, isidiate, without soredia, margins entire, black-rimmed. Isidia short, subglobose at first becoming cylindrical, slender, simple or sparingly branched. Lower surface black, glossy, smooth, rhizinate. Rhizines sparse to moderately dense, short, simple, black. Apothecia sessile, to 6 mm diam., disc concave to undulate-distorted, brown to dark-brown; thalline exciple thick, involute to undulate, isidiate. Ascospores 7.5–8.5 × 5–6.5 μm. Pycnidia common. Conidia bacillar to bifusiform, 4–6 × 0.5 μm.
Chemistry : Cortex K−; medulla K+ yellow→dark-red, C−, KC+ red, Pd+orange; containing usnic, salazinic (major) and consalazinic acids.
N: Northland , Auckland, South Auckland (Coromandel Peninsula) S: Nelson (Puponga), Otago (Central Otago), Southland (Fiordland). St: (Cooks Arm, Port Pegasus). On coastal rocks, rarely inland in arid habitats. Known also from Mexico, Australia, Papua New Guinea and New Caledonia (Elix et al. 1986b: 273; Elix 1994s: 255; Louwhoff & Elix 2002b; McCarthy 2003c, 2006; Nash & Elix 2004; Nash et al. 2004a).
Palaeotropical
Illustrations : Elix et al. (1986b: 273, fig. 25); Hale (1990: 130, fig. 45D).
Xanthoparmelia isidiigera is characterised by: the saxicolous habit; the black lower surface; sparse, very slender and sparingly branched isidia; and salazinic acid in the medulla. X. australasica has a an identical chemistry but in that species the isidia are densely congested and coralloid-branched, and its lobes are broader and more loosely adnate.
