Distinguished from other species of the genus by its thalline chemistry (hypostictic acid) and sequence data.
Typus: Falkland Islands. East Falkland, Lafonia, 3.5 km west of Walker Creek, east side of stream north of road, 51.97705°S, 58.82285°W, 21 m, low dolerite outcrop in Empetrum heath above stream, 12 November 2015, A.M. Fryday 11433 & A. Orange (MSC—holotype).
Thallus: effuse, several centimeters across, cream to grey, areolate; areoles angular, convex, 0.2–0.5 mm across, usually contiguous but sometimes singular or in small groups on a black hypothallus, areoles separated by deep cracks. Prothallus black, fimbriate at the thallus edge, 0.5 mm wide. Upper cortex c. 50 µm thick with a thin epinecral layer 10–25 µm thick, upper 25 µm of cortex grey in visible light due to medium sized crystals that only partially dissolve in K, crystals often most frequent between the cortex and the epinecral layer, cortical cells not observed in pale-colored areoles but grey areas had cortical cells 5–6 µm diam. with a thin, pale grey-brown cap; lateral cortex pale brown due to numerous minute crystals that do not dissolve in K, slightly POL+, cells 5–8 µm diam. Photobiont layer c. 25 µm thick, cells chlorococcoid, 6–16 µm diam.
Apothecia abundant, usually immersed (aspicilioid) but sometimes becoming sessile with a prominent proper margin, black, 0.4–0.5 mm diam. when mature, usually 1/areole, (occasionally two, rarely three); usually ±round, rarely oblong or linear, angular if >1/areole; thalline margin not apparent, formed by the thalline areole; proper margin densely pruinose when immature becoming epruinose, 0.1 mm wide; disc black, slightly concave, pruinose when immature becoming epruinose when mature. In section: exciple up to 250 µm wide at the surface tapering to nothing where it merges with the subhymenium, pale brown but darker at the surface that is N+ green, composed of narrow (1–1.5 µm wide) conglutinated hyphae that become wider (c. 5 µm) and cellular with constricted septa for the final 4–5 cells towards the cortex. Hymenium 140–160 µm, I+ slowly yellow and after c. 5 minutes greenish-blue; paraphyses very fine c. 1 µm, the upper 20–25 µm (epihymenium) wider (5 µm) with constricted septa, cells globose to oblong 5 µm wide by 5–7 µm long; epihymenium olive-brown (K+ brown, N+ bright aeruginose; caesiocinerea-green); subhymenium hyaline, I+ slowly (after c. 5 minutes) dark -blue, composed of ±vertically aligned hyphae with the same kind of medium sized hyaline crystals as in the cortex, merging with the hypothecium. Hypothecium hyaline, I+ slowly (after c. 5 minutes) bluish-mauve, composed of thick (c. 5 µm) randomly organized hyphae. Asci cylindrical when immature, c. 110 × 20 µm, becoming broadly clavate when mature, 80–90 × 40–45 µm; ascospores 8/ascus, hyaline, broadly ellipsoid, (22–)24.55±1.63(–30) × (11–)14.65±1.53(–18) µm, l/b ratio (1.28–)1.69±0.19(–2.18), n=20.
Pycnidia not observed.
Chemistry Thallus C–. K–. KC–. Pd–, but in section slowly K+ yellow. TLC (solvent C): hypostictic acid (red spot at Rf 4), feint red spot at Rf 1 (?subhypostictic acid), UV(after charring)++ cream spot at Rf 8.