Lobarina scrobiculata  

Thallus to 10 cm wide, irregularly lobate; lobes 1-3 cm wide, rounded, often concave, the margin entire or slightly crenulate; upper surface dark bluish green or deep greyish blue when wet, yellowish green when dry, pitted with large, shallow depressions, slightly ridged but ridges not forming distinct network; soredia blue-grey, at first punctiform, becoming irregular and spreading along ridges and lobe margins; lower surface pale brown, tomentose, reticulate, convex areas corresponding to hollows in upper surface, whitish, without tomentum; photobiont cyanobacterial (?Nostoc).
Anamorph: conidiomata not seen.
Teleomorph: ascomata apothecia, infrequent, disc 1-2 mm diam., red-brown with thick, inflexed, sometimes sorediate thalline exciple. Ascospores 18-23 × 4-7 μm, 1- to 3-septate, colourless, elongate-fusiform.
Chemistry: Medulla C–, K+ yellow, KC+ deep orange-pink, Pd+ orange, UV+ violet-glaucous. Two chemotypes: 1) usnic acid, stictic acid + satellites incl. norstictic acid, scrobiculin with two satellites, 2) usnic acid, scrobiculin with two satellites.