Sticta ciliata Taylor
Sticta fuliginosa auct. europ. p. p.
Thallus foliose, composed of one or several large lobes emerging from a pseudo-stipe and in that case rosette-shaped, 3-5 cm diam., lobe margins rounded, more or less regular, rolled up, growing lobe margins minutely cilate, cilia 0.2-0.5 mm long, whitish (not to be confused with up-turned lower surface tomentum). When wet, thallus firmness more or less papyraceous, but easily breakable when dry, fish smell induced by KOH trituration or when wet. Upper surface smooth at first then slightly scrobiculate (having minute depressions), grey-brownish, dark grey, dark brown-chocolate, darkened with numerous cylindrical or coralloid isidia, 0.2-0.5 mm, often clustered in small mounds, brown-blackish tinged blue or black; lower surface markedly tomentose or pubescent, sometimes dishevelled, cream to pale brown, darker towards the center with abundant minute cup-shaped cyphellae, more or less angular and uneven, 1-1.2 mm diam., paler, typically cyphella membrane shows papillae when observed with a microscope, 1-2 x 1-1.5 µm. Apothecia very rare, outbreaks seemingly random and seasonal, fleeting, distributed in lines towards the upper surface margins, as the ocelli of butterfly's wings, 2-3 mm diam., disc bright, brown-red, flat to concave, thalline exciple markedly ciliate, 200-300 x 5-7 µm, white or white-orange at first, then somewhat ciliate-crenulate, and excluded when mature at a time where the disc solely remains as a dull brown-reddish small dome-shaped protuberance. Ascii: 65-100 x 17-33 µm. Ascospores narrowly ellipsoid, slightly curved or fusiform, apices pointed, 1-(2-3)-septate, 26-46 x 7-8.5 µm (35-45 (-50) x 6-9 (-10-12) µm according to our own measures). Photobiont: Nostoc. Chemical spot tests negative but fresh specimen produce a fish smell. Rare, on rocks and at the base of mossy rocks and trunk bases in humid locations subjected to oceanic climate. N.B. Young specimen without abundant isidia and still undarkened are easily mistaken with Sticta sylvatica. See also Sticta fuliginosa ss. str. of which the lobes margin is not or very little ciliate and very seldom fertile.
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. Freely available at : http://hdl.handle.net/2268/186416