Pyrenula nitidella (Flörke ex Schaer.) Müll. Arg.

     Thallus rather thin, smooth and bright, brown-olive when moist, brown-tawny when dry, punctuated of whitish pseudocyphella, brownish hypothallus, undistinct, except in case of contact with other species. Perithecia not abundant, grouped in the center of the thallus, a bit flattened and not so promiment, 0.2-0.3mm diam. (often of unequal size on the same thallus), hymenium K+ purple. Spores 3-septed, 22-26 x 8-11 µm. C-, K+/- yellow, KC +/- yellow, P-, UV-. Uncommon species (or confused!) coming on bark more or less smooth of deciduous trees in rain forest. Be aware that Pyrenula chlorospila is very similar but UV+ white and its spores are larger, and that Pyrenula nitida is K+ red-orange.*