Biatora efflorescens (Hedl.) Räsänen
Lecidea epixanthoidiza Nyl.
Thallus crustose, cracked, greenish-gray, covered with granular punctate soralia 0.2-0.5 µm in diameter, green. Apothecia often rare or absent, otherwise buried at first in soralia then slightly sessile, convex then strongly rounded and even subglobular, 0.5-1 mm in diameter, pale brownish, reddish brown, brownish, paler margin disappearing quickly. Spores narrowly elliptical with rounded (cigar-shaped) ends, colorless, 0- (1) septate, 12-18 x 3-5 µm according to the literature, 10-15 x 3-4 µm according to our measurements. Thallus and soralia: C-, K-, KC-, P + orange, red-orange. Rare, or unnoticed, species occurring on the bark of deciduous trees (Quercus) in old oceanic forests. Very similar to Biatora britannica which is distinguished by its bluish-gray, blackish-gray, blackish apothecia, but there seem to be intermediaries. Very similar also to Phyllopsora rosei, but the latter species is subsquamular and its scales are bordered by cilia of whitish cottony appearance.