Distinguished from all other species of the genus by its long ascospores (15–23 × 2.5–3 µm).
Type: Falkland Islands, East Falkland, Stanley Common, outcrops along Goat Ridge, 600 ft, 30 January 1968, Imshaug 41510 & Harris (MSC—holotype).
Description
Thallus effuse, white, thin, <50 µm thick, with rock grains protruding through the surface, rimose to cracked-areolate; medulla I–. Photobiont trebouxioid; cells 6–15 µm diam. with a thick hyaline wall.
Apothecia biatorine, pale orange to pink, 0.3–0.5 mm; disc flat, sometimes becoming convex, white pruinose; margin paler than disc, barely raised, 0.03 mm wide, barely visible in convex apothecia. In section:proper exciple 30 µm wide, composed of narrow (1.5 µm wide), branched and anastomosing hyphae, inspersed with granular crystals that dissolve in K to give a bright yellow solution; cortex absent. Hymenium 40–50 µm high, upper 10–20 µm with granular crystals that mostly dissolve in K; paraphyses narrow 1.5 µm wide, widening at the apex to 4 µm, sparingly branched and anastomosing. Hypothecium hyaline 80–100 µm, well differentiated from the hymenium, composed of randomly orientated hyphae, inspersed with granular crystals that dissolve in K giving a bright yellow solution. AsciBiatora-type, initially cylindrical, becoming clavate 25–30 × 10–12 µm; ascospores hyaline, acicular, 1(–3)-septate, tapering at lower end, usually straight, rarely curved, (15–)19.90±2.02(–23) × (2.5–)2.80±0.25(–3.0) µm, l/b ratio (5.00–)7.167±0.99(–8.80), (n = 20).
Conidiomata not observed.
Chemistry. K–, C–, KC–, Pd–; thallus too thin for TLC.
Etymology. The name refers to the long ascospores, which are unique for the genus.
Distribution and Ecology. Known only from the Falkland Islands. Reported from siliceous rocks on both main islands, usually at relatively high altitude (180 m), although one collection is from <100 m. Associated species: Cliostomum albidum Fryday, Lithographa opegraphoides Coppins & Fryday.