Catinaria atropurpurea (Schaer.) Vezda & Poelt
Catillaria atropurpurea (Schaer.) Th. Fr.
Biatora atropurpurea (Schaer.) Hepp
Biatorina atropurpurea (Schaer.) Massal.
Thallus poorly defined and sometimes inconspicuous, thin and showing the bark below, greyish, gray-brownish, smooth to somewhat grainy. Apothecia small, 0.2-0.5 mm in diameter, typically reddish-brown, wine-red a little purple if fresh and moist, blackish if dry and old, disc flat, rim quite thick, hyaline and like gelatinous if cool and humid, disappearing in old age. Utriform asci with 8 spores. Ascospores quite variable but in general elliptical with a thick wall (which can make think of a halo), colorless, 0-1 septate, 10-15 x 5-7 according to the literature; 10-14 x 5-6 µm according to our measurements. Photobiont: chlorococcoid. No significant color chemical reactions. Uncommon (or neglected) species occurring on the bark of trees in oceanic forests (Fraxinus, Quercus). N.B. Species that can be recognized in the field (so fresh and in humid weather) by its small gelatinous apothecia, reddish brown a little purple with a margin.