Description
Thallus forming small rounded patches to 2 cm diam. or more wide-spreading, not sharply delimited, rimose-areolate, with angular areoles c. 0.150.5 mm wide, buff to pale tan-brown, matt; prothallus not evident. In sections to c. 100 m thick, ecorticate but with a hyaline, c. 58 m thick epinecral layer; medulla thin, but thicker where the thallus crosses microfissures in the substratum, containing large amounts of mineral fragments, patchily I+ blue. Photobiont cells globose, 712 m diam.
Apothecia lirelliform, essentially fusiform in outline with acute apices, straight to slightly curved, simple or once branched, innate in the thallus or margin becoming raised above the surface level of the thallus, but then the apices remain embedded in the areoles, 0.151 0.080.2 mm, black; disc slit-like at first but usually expanding, epruinose; margin raised, c. 0.030.07 mm wide, when dry an adhering skin of thallus tissue can give the appearance of a thalline margin. Exciple cupulate, reddish brown, K, N, c. 2550 m thick at base, 1737 m thick laterally, sometimes widening to 70 m at the apex (margin). Hymenium 5262 m tall, hyaline or dilute reddish brown, I+ blue; epithecium usually well defined, c. 7 m tall, dark reddish brown. Hypothecium c. 1225 m tall, mottled reddish brown. Paraphyses rather sparse, sparingly branched or anastomosing, distinctly septate but not moniliform, 11.7 m wide in mid-hymenium, up to 3 m wide at the clavate apices; apices embedded in pigmented matrix and some are provided with a thin, dark brown hood. Asci clavate, 4149 1218 m, 8-spored; in K/I with amyloid outer wall, and tholus with a thin amyloid apical cap and amyloid flanks (Trapelia-type). Ascospores (7)911 46 m, ellipsoid, simple, hyaline, without a distinct perispore.
Pycnidia immersed, black, c. 5060 m diam.; wall reddish brown. Conidia narrowly bacilliform, but sometimes wider at the proximal end, 68 c. 0.8 m.

Chemistry. Thallus K, C, KC, P, UV; low quantities of atranorin, zeorin and protocetraric acid detected by TLC, but this should be confirmed as these may be the result of contamination.

Ecology and distribution. Known only from the type locality on the Falkland Islands, where it grew on a siliceous rock outcrop on a ridge at c. 180 m altitude. The type material is accompanied by a Bacidia species with a pallid, rimose-areolate thallus and concolorous, marginate apothecia. In sections this has an inspersed hymenium (crystals dissolving in K) and shortly acicular ascospores, c. 2225 1.8 m.

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Thallus