Trypethelium astroideum

The thallus is corticate, with a cortex 40–80 μm thick. It is smooth to somewhat swollen (bullate), continuous, somewhat shiny, olive-green, up to 7 cm across, and about 0.5 mm thick. It induces swellings of the host bark but is not surrounded by a black prothallus.^[2]

The pseudostromata are raised, irregular to star-like in outline, 1.0–1.5 × 1–3 mm and about 0.8 mm high, with sloping sides. Their surfaces are similar to or slightly paler than the thallus, bordered paler, and contain black ostiolar areas overlaid with rust-red pigment. Internally they contain orange granular pigment and parietin, embedded in bark tissue. The ascomata are pear-shaped (pyriform), 0.3–0.6 mm in diameter, aggregated within the pseudostromata. Their walls are fully carbonized, not layered, and up to 100 μm wide. Ostioles are mostly fused, eccentric to apical, convex, and black, each surrounded by a rust-red pigmented spot that often forms a star-shaped pattern. The hamathecium is clear. The asci contain eight spores each. The ascospores are colorless, spindle-shaped (fusiform), with rounded ends, divided by 12–22 septa, and measure 65–100 × 11–14 μm. They have rounded lumina and no gelatinous sheath. Pycnidia have not been observed.^[2]

The thallus surface is UV− and K−, and the medulla is K−. The pseudostromata surface is UV−, while the rust-red pigment near the ostioles reacts K+ purple (not dissolving). Inside the pseudostromata, the granular orange pigment reacts K+ carmine red (dissolving). Thin-layer chromatography detected parietin (minor) and an additional unidentified anthraquinone (trace).^[2]

Trypethelium astroideum grows on smooth bark of trees in lowland rainforest and in Moxos savannah. At the time of its original publication, it was known to occur only in Bolivia, where it has been collected in Santa Cruz and Pando Departments.^[2]