Description: Thallus crustose, thinly episubstratic or partly endosubstratic, grey-brown, uneven, corticate, 60-130 µm thick, the cortex irregular in thickness, 15-25 µm thick, of subglobose, mainly 2-2.5 µm wide cells, the hyphae in the photobiont layer thin-walled, branched, septate, hyaline, (1.5-)2-3(-4) µm thick, penetrating the outer layers of periderm cells. Conidiomata sporodochial, superficial, grey to olivaceous grey but often eroded and appearing white, pulverulent, up to 0.4 mm across and up to 0.1 mm high, initially punctiform, then circular to ellipsoid, strongly convex, solitary or sometimes in clusters of 2-5, consisting of a base of loosely aggregated, hyaline hyphae from which ascending branches bear conidia at different levels. Conidiophores hyaline, septate, irregularly and repeatedly branched, 2-2.5 µm wide towards the base, progressively wider (up to 10 µm) towards the apex, the individual cells markedly constricted at septa, the cell walls 1-2 µm thick, formed from the basal cells of the conidiomata. Conidia up to 35 x 22-35 µm, hyaline when young, turning pale brown at base at maturity, smooth, flabelliform to palmate, consisting of a globose-truncate basal cell measuring (6.5-)8.4(-9.5) µm, from which usually 2 diverging dichotomous branches arise, each of which branches again, either dichotomously or irregularly, finally producing a conidium with 4-10 arms, the arms 4-9-distoseptate, with reduced cell lumina, straight or slightly curved, obtuse, measuring (10-)13-18(-20) x 3.5-5 µm. Photobiont chlorococcoid, the cells 6-10 µm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on acid bark, more rarely on wood in humid, sheltered situations, mostly in upland areas. The Italian sample was collected on a stump of Picea. The species is included in the Italian red list of epiphytic lichens as “Data Deficient” (Nascimbene & al. 2013c).