Astrothelium trematum

The thallus of Astrothelium trematum is dull, up to 0.3 mm thick, and pale olivaceous green, with a thick cortex and a medulla containing hyaline crystals. It is not surrounded by a prothallus. Ascomata are spherical to pyriform, 0.6–0.9 mm in diameter, solitary in pseudostromatal warts. The pseudostroma is low hemispherical, almost completely covered by a thallus layer, about 1–1.5 mm in diameter, and without pigmentation. Ostioles are apical, consisting of exposed carbonized, black ascoma wall, about 0.2 mm wide, surrounded by a whitish ring of approximately 0.3 mm in diameter. The hamathecium is not inspersed. Ascospores number eight per ascus, and are hyaline with 5 to 7 septa, measuring 95–135 by 25–33 μm. They have a long ellipsoid shape with internal diamond-shaped lumina. Pycnidia were not observed.^[2]

The thallus of Astrothelium trematum is UV−, C−, K−, KC−, and P−. Thin-layer chromatography analysis did not detect any secondary metabolites.^[2]

Astrothelium trematum was found on tree bark in a cocoa plantation, and at the time of its original publication, was known only to occur in Brazil.^[2]