Distribution: N - Lig (Giordani & Incerti 2008). C - Tosc (Loppi & al. 1997c, 1999a, 2004c, Putortì & al. 1999c, Senese & Critelli 2000), Sar (Lumbsch 1994, Loi & al. 2000, Zedda 2002, 2002b). S - Camp (Nimis & Tretiach 2004, Garofalo & al. 2010), Pugl (Nimis & Tretiach 1999), Bas, Si (Nimis & al. 1994).
Description: Thallus crustose, episubstratic, whitish, continuous to granulose. Apothecia lecanorine, 0.5-1.5 mm across, sessile and constricted at base, with a pale to dark reddish brown, sometimes faintly pruinose, flat to strongly convex disc, and an initially thick, finally thin to excluded, smooth to crenulated thalline margin, sometimes with a distinct parathecial ring. Amphitecium c. 30 μm thick, strongly gelatinized, inspersed with small crystals, the medulla with many algae and with large crystals insoluble in K, best visible under polarized light; epithecium pale brown, the epipsamma with large granules dissolving in K, reacting K+ red; hymenium colourless, >80 μm high; paraphyses coherent, thin, mostly simple, rarely branched-anastomosing in upper part. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid to slightly bifusifom, c. 11-12 x 5-6 μm. Photobiont chlorococcoid. Spot tests: thallus and apothecial disc K+ yellow turning deep red (needle-like red crystals), C- KC-, P+ orange. Chemistry: atranorin, norstictic acid.
Note: a mainly Mediterranean lichen found on smooth bark in open maquis and garrigue vegetation; confused with L. chlarotera in the past, but certainly not common.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)