Lichenologist 13, 1: 39 (1981).
Basionym: Parmeliella duplomarginata P. James & Henssen, in Henssen & James, Mycotaxon 11, 1: 221 (1980).
Type locality: New Zealand, North Island, South Auckland, Rotoiti Bush, S.-E. of Lake Rotoehu, 19 May 1927, G. E. & G. Du Rietz 3117, see note below (UPSV - holotype; BM, MB - isotypes).
Type locality coordinates: Data lacking.
Molecular barcode: Data lacking.
Thallus: foliose, + orbicular to spreading, loosely attached, or sometimes closely appressed, 5-8(-12) cm diam. Lobes witish grey to leaden grey when dry, darker bluish-grey when moist, 0.3-0.6(-1.0) cm wide, adjacent, often imbricate, broadly cuneate to flabellate, apices rounded, margins entire or occasionally minutely notched or incised, + incised, + deflexed. Upper surface smooth or minutely wrinkled, rather coriaceous, matt, without isidia, usually with transverse, concentric ridges, often with regenerating lobules in older parts of the thallus. Lower surface usually pale but sometimes dark, with a dense felt of rhizines usually arranged in concentric lines. Rhizines whitish, often turning bluish or entirely black, usually not projecting beyond lobe margins. Apothecia + frequent, to 2.0 mm diam. Disc concave when young becoming plane (rarely slightly convex) when old, usually reddish-brown sometimes becoming blackened with age. Apothecia with a double margin. Proper margin prominent in young apothecia, rising above the disc, however in old apothecia visible only as a pale (or rarely dark) line, or completely occluded by the thalline margin. Thalline margin crenulate, of + fused, small flattened lobules arising from the base of the apothecia. Anatomy: ... (Arvidsson & Galloway 1981: 39). Spores with granular surface (Arvidsson 1981: 199).
Photobiont: Data lacking.
Chemistry: No lichen substances.
Ecology: Data lacking.
Distribution Type: New Zealand, USA: Hawaii.
Note: "Henssen & James (1980) are in error regarding the date of collection of the type material. G. Einar and Greta Du Rietz visited New Zealand between November 1926 and June 1927 (not 1929 as indicated)" (Arvidsson & Galloway 1981: 39).