Glaucotrema thailandicum

The thallus is endophloeodal to epiphloeodal, pale green to yellowish green, smooth, and up to about 120 μm thick, with a more or less continuous true cortex up to about 25 μm thick. Calcium oxalate crystals are reported as sparse to abundant, and the medulla is usually distinct. Vegetative propagules were not observed.^[2]

The fruiting bodies (ascomata) are conspicuous, about 0.8–1.2 mm in diameter (sometimes larger when fused), and may occur singly but more often merge. They become slightly to distinctly raised above the thallus surface and are typically urn-shaped (urceolate). The disc is usually only partly visible from above and is pale yellowish to whitish green. The pore-like openings are broad to gaping, up to about 0.6–0.8 mm wide. The spore-bearing layer (hymenium) is clear and strongly glued together (conglutinated), with a whitish, net-patterned central column (columella). Each ascus contains eight colourless (hyaline), slightly iodine-staining (slightly amyloid) ascospores with a few transverse and longitudinal cross-walls (submuriform, with 3 × 0–1 septa); the spores measure 15–20 × 7.5 µm.^[2]

The species is known from Thailand, where the type was collected in dry evergreen forest in Pha Taem National Park (Ubon Ratchathani Province) at 124 m elevation, growing on bark.^[2] It is one of three Glaucotrema species that have been recorded in the country (including G. costaricense and G. glaucophaenum).^[3]