Thallus 2-3 (-5) cm diam., initially developing as a single shallowly vase- or trumpet-shaped structure with revolute margins (appearing like a mushroom), often with a distinct stipe, eventually developing several irregular to suborbicular overlapping lobes, leathery but often brittle when dry, when old often with a crenate to lacerate margin. Upper surface smooth to mildly scrobiculate, greyish to dark brown (in wet or dry conditions), matt or slightly glossy. Cilia usually absent, sometimes present on small or regenerating lobes, simple, white, to 500 µm in length. Isidia always present, abundant, laminal, first simple and globose or with a flattened top, eventually forming upright coralloid masses to 200 µm high, sometimes with substipitate lobules on old thalli, similarly coloured or darker than the thallus. Lower surface smooth to scrobiculate, sometimes strongly so, pale orange to brownish, darker towards the center on old thalli, sparsely to densely tomentose the hairs fasciculate, especially towards the centre. Cyphellae usually abundant, round or angular, urceolate with a wide pore, erumpent to prominent, the margin elevated and involute, whitish to cream-colored, rarely brownish, 400-600 µm diam., the surface cells papillate, the papillae 4-6 (-8) per cell, 1-2 µm diam. Photobiont Nostoc.
Anamorph: not known.
Teleomorph: not known.
Not yet assessed; it would certainly be considered to be Data Deficient due to the difficulty of assigning old records to this or S. fuliginoides sensu stricto. Initial, very preliminary indications are that this species may be commoner than S. fuliginosa, at least in SW England.
Differentiated from S. fuliginosa sensu stricto by the usually relatively small thalli that are mushroom-shaped with revolute margins at least when yound, and the surface cells of the cyphellae which are papillate.
Currently known from VC1 W Cornwall, VC2 E Cornwall, VC4 N Devon and VC49 Caernarvonshire.
On mossy trees and damp rocks in humid, sheltered situations, in ancient, oceanic woodlands - but perhaps in more open sites than S. fuliginosa and S. ciliata.