Sticta sylvatica (Huds.) Ach.
Thallus foliose, 10-15 cm across, lobes markedly incised, dichotomously branched, 1-1.5 cm wide, dark brown, light brown, bronze, upper surface irregularly and minutely furrowed and humpy or scrobiculate, covered with globose isidia, coralloid notably along furrows, brown-blackish, grey-brown when moist, grey-bluish when dry, lower surface pubescent (carpet-like), dark brown, with numerous cyphella, white, small, cupule-shaped inserted whithin the thallus, 0.5-1 mm diam.. Apothecia unknown. Photobiont: Nostoc. Chemical spot tests negative although a small fragment, after crushing, notably in presence of K, produces a rotten fish smell (methylamine?). Rather uncommon, on mossy bark of trunks or rocks in shaded very humid old oceanic woodlands. Not to be confused with Pseudocyphellaria intricata that is rather similar but extremely rare and with lobe margins edged with bluish soralia.*
For more details, refer to:
MAGAIN N., SERUSIAUX E. Mycol Progress (2015) 14:97. Dismantling the treasured flagship lichen Sticta fuliginosa (Peltigerales) into four species in Western Europe. Download : http://hdl.handle.net/2268/186416