Xanthoparmelia digitiformis
≡Parmelia digitiformis Elix & P.M.Armstr., Austral. J. Bot. 31: 470 (1983).
Description : Thallus loosely adnate on rock, pale yellow-green, blackening with age, to 20 cm diam. Lobes 1.5–3 mm wide, subirregular, strongly imbricate, apices ±rounded, secondary lobes similar to marginal lobes but narrower (1–2 mm wide), elongate, digitately to subdigitately divided, building up thallus into a thick mat. Upper surface glossy, emaculate, older lobes becoming wrinkled, matt and cracked, margins often blackened; without isidia or soredia. Lower surface brown to dark-brown, darker towards apices, sparsely rhizinate. Rhizines simple, slender, concolorous with lower surface. Apothecia to 6 mm diam.; thalline exciple thin, crenulate to flexuous, involute at first, almost disappearing at maturity; disc dark-brown, matt, concave, smooth to wrinkled. Ascospores 7–10 × 4–6 μm.
Chemistry : Cortex K−; medulla K+ yellow→dark-red; C−, KC−, P+ yellow-orange; containing salazinic, consalazinic, ±norstictic (tr.), protocetraric (tr.) and usnic acids.
N: Black Birch Ra., 1200–1250 m. S: Nelson (Mt Trovatore), Otago (Lindis River near Cluden, Glendhu Bluff Lake Wanaka, Butcher's Dam near Alexandra). Subalpine to alpine on rock, 400–1500 m. Known also from upland and dry subalpine areas in Australia and Tasmania (Elix 1994s: 233; McCarthy 2003c, 2006), and from Arizona and Baja Califonia (Nash & Elix 2004; Nash et al. 2004a).
?Circum-Pacific
Illustrations : Elix & Armstrong (1983: 470, fig. 3 – as Parmelia digitiformis); Elix (1994s: 231, fig. 95D).
Xanthoparmelia digitiformis is characterised by: the saxicolous habit; the pale lower surface; the absence of isidia; and the presence of salazinic and consalazinic acid in the medulla.
