Thallus crustose, epilithic, c. 1–2 cm wide, effuse, determinate or partly eroded, continuous towards the margin, rimose to sparingly areolate towards the center, off-white to pale greenish, smooth to rugulose or verruculose (largely determined by the microtopography of the substratum), 30–50–(60) µm thick, lacking a dark basal layer, corticate, K–, calcium oxalate crystals absent. Cortex hyaline, paraplectenchymatous, 10–15–(20) µm thick; cells tightly packed, angular to rounded, 3–5–(6) µm wide. Algae Trentepohlia; cells broadly ellipsoid to globose, 8–16 × 7–12 µm. Interstitial hyphae moniliform to long-celled, 2–4–(6) µm thick. Prothallus a thin, discontinuous brownish black line, or not apparent.
Ascomata perithecia, numerous, solitary or in short rows or small clusters, partly immersed in thalline verrucae, convex to hemispherical, often appearing superficial where the surrounding thallus has been eroded, (0.25)–0.33–(0.46) mm diam. , outwardly dull to glossy brownish black or black at the apex or in the upper half, or almost completely dark; often the lower parts distinctly thalline; apex rounded or distorted; ostiole inconspicuous or in a shallow c. 30–50 µm wide depression. Involucrellum ± apical or extending more than half-way to excipulum-base level, 50–70 µm thick, outer layers dark olive-brown to blackish brown in thin section, reddish brown or orange-brown internally, the colours darkening and intensifying in K; ostiolar region occasionally with a bluish tint that is K+ grey. Centrum subglobose to depressed-obovate, 0.18–0.26 mm wide. Excipulum c. 20–25 µm thick at the base and sides of the centrum, predominantly hyaline from base to apex, the outer layers pale to medium orange-brown or greenish brown, K+ pinkish red. Subhymenium 25–35 µm deep. Paraphyses unbranched, 0.8–1.2 µm thick. Periphyses absent. Asci 8-spored, with a rounded or subtruncate apex and a indistinct, apical chitinoid ring that darkens in Congo Red, 120–138 × 7–9 µm . Ascospores oblong to fusiform, mostly straight, usually with pointed ends, overlapping-uniseriate or slightly oblique in the ascus, hyaline, 3-septate, (19)–22.0–(27) × (4)–4.8–(6) µm ; perispore very thin or not apparent; contents usually clear. Conidiomata pycnidial, moderately numerous, semi-immersed to almost completely immersed in the thallus, 0.1–0.15 mm diam., plane to convex and dark greenish brown above, hyaline below, with a simple to richly convoluted conidiogenous layer. Conidia simple, elongate-ellipsoid to fusiform or bacilliform, 2–3–(3.5) × 0.5–0.7 µm.
Ecology and distribution. Siliceous stones and rock. Known only from the Falkland Island and the Brunswick peninsula in southern Chile.