Byssoloma maderense O. Breuss

    Thallus thin, smooth to very finely rough, dull, greenish, greenish-gray. Apothecia numerous, rounded, 0.3-0.8 mm in diameter, adnate, flat to weakly convex, disc, greyish-brown, brownish, sometimes slightly pruinose, margin relatively fine but clearly distinct, white "byssidoid" (cottony); With a magnifying glass the discs can appear pruinose by the presence of numerous colorless crystals. These crystals, present in the epihymenium and in the byssydoid margin are colorless and insoluble in KOH, these crystals are clearly visible under a polarizing microscope and are characteristic of the species, brown hypothecium, colorless hymenium, unbranched paraphyses. 8-spores claved asci. Spores oblong, colorless with a thin perispore, 3-septate, 10-15 x 3-4 µm according to the literature, 12-15 x 3-4.5 µm according to our measurements. Rare and inconspicuous species occurring on the bark of deciduous branches (more rarely the trunks) in oceanic forests (especially by the sea).

N.B. Species formerly confused with Byssoloma leucoblepharum and in practice indistinguishable in the field, the differential character: crystals on the epihymenium and in the byssydoid margin can only be observed with a polarizing microscope.