TYPE. “Habitat ad truncus arborum Indiae occidentalis.” (Acharius 1810) O.P. Swartz s.n. (H-ACH 1299, holotype).
Description. Lichenized fungus.
Thallus foliose, corticolous, slightly adnate, light grey, greenish-grey or bluish-grey, 1.8−5.0 cm in diameter and 61−110 µm thick. Lobes flabellate, (1.5−) 2.0−5.0 mm wide, upper surface smooth to slightly cuneate, usually with small concentric and radial lines, margins bent downward. Isidia marginal and occasionally lamellar, flattened scale-like or in the form of microfilidia (0.10−0.45 x 0.10−0.47 mm). Upper cortex 8−15 µm thick. Photobiont Scytonema cyanobacteria, 30−40 µm wide. Underside white, pale brownish or bluish; rhizines black to bluish-black or rarely white. Ascomata lecarnorine apothecia; disk convex, yellow-orange or brownish red, 1 mm diam. Exciple yellow−orange, 80 µm thick; epithecium 9 µm tall, orange to dark brown; hymenium 45−60 µm high, pale yellow; hypothecium 60 µm tall, light yellow to orange. Paraphyses simple, septate, sometimes with dilated apex, 45−50 µm high by 3−4 µm wide. Asci claviform, unitunicate, usually 8-spored, internal and/or external amyloid layers, 40−50 µm long by 8−11 µm wide. Ascospores simple, hyaline, ellipsoid to fusiform 10 x 4 µm. Pycnidia laminar or marginal, 0.06−0.10 (−0.22) mm in diameter, brown to black or bluish-black ostiole.