Thallus effuse, widespreading to 5–10 cm or more, on soil; continuous, yellowish-fawn. Photobiont chlorococcoid, cells 8–12µm diam.
Apothecia flat, lecidine, 0.8–1.2 mm diam., black with bluish tinge, proper margin 0.5 mm wide, prominent and raised when young, level with disk in old apothecia. Hymenium 75 –80 µm high, merging into the hypothecium, epihymenial zone 10–15 µm high, blue-green (HCl+ blue, N+ purple-red); paraphyses mostly simple, septate, 1–2 µm wide, not widening at the apex and without pigmentation. Hypothecium composed of randomly arranged, hyaline or pale straw-coloured, periclinally layered below and towards exciple. Exciple composed of fine, branched and anastomosing hyphae c. 1µm wide, hyaline with a brownish rim (HCl+ greenish-brown, N+ red-orange). Asci Lecanora-type, 55–65 × 18–20(–25 µm, cylindrical, becoming somewhat clavate; ascospores simple, hyaline, ellipsoid, (15–)16–18(–21) × (7–)8–9(–10) µm.
Conidiomata pycnidia, pale orange, 0.1–0.3 mm diam., initially immersed but becoming emergent and almost adnate, with a roughened surface, conidia filiform straight or hamate to curved (25–)30–35(–50) × 0.8–1.2 µm.
Chemistry: C–, K+ yellow, KC+ orange, Pd–, UV+ yellow
TLC: atranorin and unidentified substances
HPLC: atranorin [major], 2,5,7-trichloro-3-O-methylnorlichexanthone [major], 5,7-dichloro-3-O-methylnorlichexanthone [minor], isoarthothelin [minor], chodatin [minor]. (Thanks to Jack Elix for performing HPLC)
Known only from the Falkland Islands.
This species is closely related to L. xantholeuca, from which it differs in its much longer conidia.
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