Thallus: foliose, large, 5-10(-15) cm in diam., adnate; lobes: +flattened and elongate (up to 3 cm wide and up to 4 cm long), often dichotomously branched, imbricate or separate; tips: rounded to subtruncate, often ascending and undulate; upper surface: brown but with a bluish tinge when dry, deep bluish green to olive green when wet, smooth, dull, thinly scabrid-tomentose with small, erect hairs especially towards margin, without isidia or soredia; medulla: white, with +loosely interwoven hyphae; photobiont: Nostoc; lower surface: whitish or pale tan, +uniformly tomentose, veins and rhizines almost absent, pale interstices few or absent; Apothecia: frequent, +round, sessile, marginal, up to 7 mm in diam.; margin: smooth to crenulate; disc: flat, red-brown to brown, smooth; ascospores: colorless to pale brown, elongate fusiform, 3-5 septate, 55-70 x 5-6 µm; Pycnidia: not seen in Sonoran material; Spot tests: all negative; Secondary metabolites: tenuiorin, methyl gyrophorate, gyrophoric acid and unidentified terpenoids.; Substrate and ecology: among mosses over soil in moist habitats at relatively high elevations; World distribution: temperate and boreal regions of North America, Europe and Asia; Sonoran distribution: infrequent at higher elevations in Arizona.; Notes: Thick thalli with erect tomentum at least marginally and a non-veined lower surface characterize P. malacea and help to distuinguish it from e.g. P. elisabethae and P. neckeri, both of which have a glossy non-tomentose upper surface. When moist, it has a characteristic blue-green color. 

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

LIllosporium anamorph of Illosporium carneum parasitises discoloured thallus of Peltigera malacea

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G5 - Secure

Reasons: This lichen occurs throughout Alaska and Canada south to Arizona and New Mexico in the western U.S. mountains. This species grows in open, tundra conditions and in forests.

Comments: Accepted by Egan; and also by Hale, and Thomson; no synonyms.