Characterized by the thick thallus, orange-brown, pruinose apothecia and multi-septate, acicular ascospores, 33–45 × 5–6 µm. Further distinguished from other Bacidia species by the minute granules in the apothecia that dissolve in K to give a yellow solution.
Type: Falkland Islands, Saunders Island, Rookery Hill, 51.311717°S, 60.108491°W, 241 m, N-facing rock, 4 November 2015, Fryday 11314 (MSC—holotype).
Description
Thallus effuse, cream to grey, thick and warted, 0.5–2.0 mm thick, areolate; areoles 0.3–0.4 mm across with a rough, granular surface; medulla I–. Photobiont trebouxioid; cells 6–15 µm diam. with a thick hyaline wall.
Apothecia biatorine, pale orange-brown to grey,1.0–1.2 mm diam., constricted below, orbicular becoming slightly flexuose, flat to slightly convex; disc heavily white, granular pruinose; margin thick (0.1–0.15 mm wide), not pruinose, slightly raised and persistent. In section: proper exciple well-developed, c. 300 µm wide, cupular, pale yellow-brown laterally, hyaline below the hypothecium, inspersed with fine granules that dissolve in K to give a yellow solution but insoluble in N, composed of radiating branched and anastomosing hyphae, 2–3 µm wide, not enlarged at the outer edge. Hymenium 90–120 µm high; paraphyses ±simple, sparingly branched and anastomosing, very thin, 1.0 µm wide, widening slightly at apices to 2 µm, lax and readily separating in water except at the apex; epihymenium hyaline but upper 10–20 µm inspersed with fine brown granules that dissolve in K to give a yellow solution but are insoluble in N. Hypothecium pale yellow brown, c. 100–120 µm high, inspersed with fine granules that dissolve in K to give a yellow solution but are insoluble in N, composed of vertical hyphae above and inflated, randomly orientated hyphae below. Asci cylindrical slightly swollen towards upper end, 65–70 × 18–20 µm, Biatora/Lecanora-type with a prominent ocular chamber when immature; ascospores acicular, (7–)8.08±1.62(–12)-septate, (33–)42.08±5.84(–45) × (5.0–)5.375±0.38(–6.0) µm, l/b ratio (7.09–)7.86±1.19(–10), (n = 12), not spirally arranged in the ascus.
Conidiomata not observed.
Chemistry. K+ yellow; C–, Pd–; TLC: atranorin, yellow spot at Rf 6.5 in solvent C, ±norstictic acid (type).
Etymology. Named for the densely pruinose apothecia.
Distribution and Ecology. Known only from the Falkland Islands. Reported from siliceous rocks on both main islands as well as two of the smaller ones, usually at relatively high altitude (180–240 m), although one collection is from <100 m. Associated species: Ramboldia petraeoides (Nyl. ex C. Bab. & Mitt.) Kantvilas & Elix, Pertusaria cerebrinula Zahlbr., Usnea sp.