Phyllopsora glaucescens

The thallus of P. glaucescens is squamulose, forming an effuse mat of large squamules to about 1.5 mm wide that stand up from the bark even when young. The squamules are rounded to irregularly elongated, entire to deeply notched (incised), often thickened centrally by vein-like medullary tissue. The upper surface of the thallus is bluish-green, dull, and finely tomentose (a short, felted pubescence); the margins are the same color and also finely tomentose. No well-defined upper cortex is present; instead, the algal layer is covered by a thin, loose layer of hyphae with scattered crystals that dissolve in potassium hydroxide solution (the K test), and react K+ (yellow). The medulla likewise contains crystals dissolving in K (PD−, K+ yellow). Vegetative propagules are probably absent (though a few squamule tips may break into granular soredia). Apothecia, when present, are small (to roughly 0.8 mm), rounded, simple or conglomerate, weakly to strongly convex, pale to reddish brown, with an indistinct, often disappearing margin; internal apothecial tissues are pale and lack crystals, and are K−. Ascospores are long and needle-shaped (acicular), 33.5–54.5 × 1.5–2 μm, with indistinct pseudosepta. Pycnidia were not seen.^[2]

Phyllopsora glaucescens is known from a single lowland locality in the Peruvian Amazonia (Jenaro Herrera area), where it was recorded at six sites in primary rainforest, growing on tree bark and also on trunks of tree ferns. Additional material from the same general region was examined, but there are no confirmed records outside Peru in the cited study.^[2]