TYPE. United States. Alaska. Mt. Hayes Quadrangle. Upper Tanana River near the Gerstle River, 63°54' N, 144°53' W, lower branches of Picea glauca, 370 m, 23.VII.1965, L. Viereck 7749A (ALA, holotype; UBC, isotype).
Description.Life form: lichenized fungus.
[From Goward et al. 2012] Thallus loosely attached, moderately variable, up to 6–8 (–12) cm across; lobes irregularly branched. First-tier lobes up to 2.0 (–2.5) mm wide, loose, usually not entirely obscuring the substrate, at the tips weakly concave in cross-section to weakly convex, inwards becoming more strongly convex. Second-tier lobes loosely appressed or trailing, occasionally bearing inconspicuous apical soralopodia (see below), older thallus portions often massing into low symmetrical ridges and intervening depressions. Upper surface whitish to pastel green, brownish in exposed sites, weakly shiny throughout or occasionally dull toward thallus centre; cortex usually firm except often readily abraded near lobe tips, with occasional stress cracks, irregularly flecked with black mottling, with or without black borders as seen from above; sorediate. Vegetative propagules restricted to second-tier lobes, arising in three ontological contexts: (1) apical and marginal soralopodia, these sparse to copious, capitate to rimforming, in the latter case up to 0.4 mm across (0.5–1.0 mm along long axis) and 0.2–0.3 mm high, at length dissolving above into soredia-bearing soralia, the marginal soralopodia borne at the tips of short, scarcely tapering lobes; (2) laminal micropustules, papillae and other irregularities of the cortical surface, these abundant but localized, arising over ridges and in intervening depressions, up to 0.05–0.10 mm across, closely spaced from the first, only gradually expanding outwards from the base, at length giving rise to sorediabearing soralia, the soredia up to 20–30 mm in diameter; and (3) laminal diffuse soralia, these often well developed toward thallus centre, bearing copious diffuse soredia. Perforations sparse, inconspicuous, often arising on lower surface of first-tier lobes (check tips), also along margins of second-tier lobes. Medullary ceiling white except darkening in vicinity of old ruptures in the lower surface. Lower surface mostly black, shiny, thin, easily torn, sharply winkled or folded. Apothecia not seen. Pycnidia not seen.
Substrate and habitat. Corticolous on lower branches of Picea, both in old spruce stands, and in mixed forests with Populus.
Distribution. Western subarctic North America, apparently rare and disjunct between western Alaska and the Mackenzie delta of the Northwest Territories. Further study is needed to confirm the species’ distribution and rarity status.