Porina rosei Serus. sensu auct. brit.

    Thallus thin, superficail, greenish, green-brownish, covered with isidia, isidia simple, ramified or coral-like, 0.2 mm tall, clustered in small piles suggesting a daisy heart, greenish, green-ochre to ochre or brown-orange according to hygrometry, cortex colourless, structure well-defined and enfolding the photobiont filament(s). Perithecia usually rare or absent, 0.3-0.4 mm diam., concolourous to the thallus or pale brown-orange. Ascospores ellipsoid, 3-septate, 22-33 x 4-6 µm. Photobiont: Trentepohlia. Chemical spot tests negative. On bark of old trees, notably Quercus in ancient oceanic woodlands. N.B. This species is the host of Enterographa brezhonega. 

N.B. Most often sterile and it appears that these sterile forms are to be related to Coenogonium confusum, the "real" Porina rosei ss. stricto being a tropical species probably very rare in Europe, this is why we have specified sensu auct. brit. because it is under this name that this species appears in the records.