Synonyms: Fuscidea aggregata (Flot.) V. Wirth & Vězda; Fuscidea aggregatilis (Grummann) V. Wirth & Vězda; Fuscidea taeniarum (Malme) V. Wirth & Vězda; Lecidea aggregata (Flot.) H. Magn. non Chevall.; Lecidea aggregatilis Grummann
Distribution: N - TAA.
Description: Thallus crustose, episubstratiic, continuous to rimose, pale grey to grey-brown, often delimited by a black prothallus, the areoles contiguous, thin, slightly to strongly convex. Medulla I-. Apothecia lecideine, 0.5-2 mm across, often gathered in up to 3 mm wide clusters, sessile, at first rounded but soon very irregular in outline, with a black-brown, flat, sometimes thinly pruinose disc, and a usually slightly paler, persistent, strongly wavy proper margin. Proper exciple brown in outer part, paler within; epithecium brown; hymenium colourless or pale brown in upper part, 55-75 μm high; paraphyses weakly conglutinated, simple or sparingly branched in upper part, 1.5-2 μm thick at mid-level, the apical cell clavate, to 4 μm wide; hypothecium colourless. Asci 8-spored, clavate, with a thin external and internal K/I+ dark blue cap surrounded by a thick K/I+ pale blue apical cap, and with a K/I- apical tube in tholus, Fuscidea-type. Ascospores 1-celled, hyaline broadly ellipsoid to subglobose, (6-)9-12(-13) x 6.5-9 μm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-. Chemistry: thallus without lichen substances; apothecia with divaricatic acid.
Note: on steeply inclined to underhanging surfaces of hard siliceous rocks in upland areas.