Sticta limbata (Sm.) Ach.
Thallus foliose, made of large lobes, usually in limited number and scattered, but sometimes overlapping and more or less forming rosette, apices rounded, up to 1-2 cm wide, at first margins edged with minute star-shaped soralia, grey-bluish, pale grey, occasionally spreading onto lobe upper surface and forming minute mounds, soredia numerous, typically grey-blue, upper surface pallid grey, grey-brownish to brownish, lower surface minutely pubescent, pale brown, beige, with white cyphella, cup-shaped to urceolate, scattered, 0.3-1 mm diam.. Apothecia very rare and often absent, 2-3 mm diam., shortly stalked, disc brown-red, exciple coarse (according to some authors, apothecia are unknown). Ascospores elongate, narrowly ellipsoid, 2-3-septate, 25-36 x 7-9 µm. Photobionte: Nostoc. Chemical spot tests negative. Rather uncommon, at the base of mossy trunks and rocks in clear and well-lit areas in old oceanic woodlands. N.B. Not to be confused with Nephroma parile of which the lower surface is smooth and devoid of cyphella and with Peltigera collina characterized by rhizines on lower surface.*
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