Eremothecella nicobarica

The thallus (lichen body) forms thin, matt, pale greenish-grey patches on living leaves, typically 15–50 mm across and about 10–20 micrometres (μm) thick; it lacks a cortex and a distinct prothallus. The algal partner occurs in irregular to radiating plates of angular to rectangular cells (roughly 7–14 × 3–6 μm).^[2]

Ascomata are sharply delimited, scarcely raised, rounded to irregular discs 0.5–1.3 mm in diameter and 70–120 μm thick, dark brown to blackish-brown, and non-pruinose. The epithecium is a dense, periclinal layer (about 5–12 μm thick) that reacts K+ (sordid brown), I+ (orange-brown) and KI+ (ochraceous-yellow). The hymenium is 70–110 μm high and stains I+ (intensely orange-red), turning KI+ (blue) then quickly yellow. Paraphysoids are branched and anastomosing, about 1.0–1.5 μm wide.^[2]

Asci are obovate to more or less spherical, 65–100 × 52–70 μm, I−, with the ascus tholus KI+ (pale blue) internally. Ascospores are initially colourless, later pale brownish, clavate and gently curved, with the terminal cell enlarged and only slight constrictions at the septa; they are (14–)15–17-septate, measuring 60–72 × 10–13 μm.^[2]

Asexual structures are present: pycnidia are flattened, black, oval to drop-shaped (about 0.2–0.4 × 0.2–0.3 mm), producing very long, thread-like (filiform), multiseptate conidia 60–120 × 1.5–2.0 μm, often slightly wider at one end. Standard spot tests on the thallus are negative (K−, C−, KC−, P−) and thin-layer chromatography did not detect lichen substances.^[2]

Eremothecella nicobarica is a foliicolous lichen, growing on the surfaces of dicotyledonous leaves in the shaded understory of evergreen forest. It is known only from the type locality on Great Nicobar Island.^[2]