Synonyms: Leptogium menziesii f. fuliginosum Müll. Arg.; Leptogium menziesii var. coralloideum Jatta
Distribution: N - Lomb, Lig (Brunialti & al. 1999). C - Tosc (Benesperi & al. 2007), Laz (Ravera 2008).
Description: Thallus foliose, subgelatinous when wet, bluish grey, 3-10(-15) cm wide, loosely adnate; lobes elongate, 3-10(-15) mm broad, 100-150 µm thick, with rounded apices and often upturned margins, isidiate. Isidia cylindrical, simple or branched-coralloid, often clustered, usually concolorous with lobes, sometimes with a minute pit at apex. Lower surface with a dense white tomentum of cylindrical, 0.2-1 mm long hairs composed of cylindrical cells. Upper and lower cortex consisting of a single layer of cells; inner part without medulla, with loosely interwoven chains of Nostoc and hyphae. Apothecia rare, lecanorine, substipitate, 0.5-3 mm across, with a brown to red-brown, flat to convex disc, and an isidiate, persistent thalline margin. Proper exciple euparaplectenchymatous, 20-25 µm wide laterally; epithecium brown; hymenium colourless, 100-130 µm high; paraphyses mostly simple, 1-2 µm thick, slightly swollen at tips; hypothecium colourless or pale yellow Asci 8-spored, cylindrical-clavate, the apex thick, with a I+ blue apical dome and a I+ blue annulus projecting downwardly. Ascospores submuriform, hyaline, ellipsoid to subfusiform, 30-45 x 12-18 µm. Photobiont cyanobacterial (Nostoc in long chains). Spot tests: thallus and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mild-temperate species found on the often mossy bark of isolated trees, especially Fraxinus. A revision of herbarium material is much needed: several Italian records of L. saturninum could refer to this species.