Synonyms: Parmelia angustiphylla (Gyeln.) Gyeln.; Parmelia conspersa var. panniculosa Erichsen; Parmelia subconspersa f. marusica Gyeln.
Distribution: N - Lomb (Favero-Longo & al. 2023), VA (Matteucci & al. 2015c), Lig (Giordani & al. 2002b, Rizzi & al. 2006). C - Tosc (Benesperi 2006, 2007b, Pasquinelli 2014), Sar (Nöske 2000, Giordani & al. 2009, Rizzi & al. 2011, Neuwirth 2018 as X. 'angustifolia'). S - Si (Giordani & al. 2002b).
Description: Thallus foliose, yellowish green, loosely adnate, with subirregular to sublinear, dichotomously branched, 0.8-1.5(-2) mm wide lobes which often become densely laciniate, highly imbricate and pulvinate with age, forming regular to irregular, up to 5(-10) cm wide rosettes; lower surface jet black, with 0.2-0.8 mm long, simple, black rhizines. Upper cortex paraplectenchymatous, with a pored epicortex, the cell walls with Xanthoparmelia-type lichenan; medulla white. Apothecia lecanorine, 3-10 mm across, substipitate, with a concave to flat, brown disc, and a rather thin thalline margin. Epithecium brown; hymenium and hypothecium colourless. Asci 8-spored, thick-walled, the apex I+ blue with a wide, divergent axial body, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 9-10 x 5-6 μm. Pycnidia common, black, immersed. Conidia dumbbell-shaped, 5-6 μm long. Photobiont chlorococcoid. Spot tests: cortex K-, KC-, KC+ yellowish, P-; medulla K+ yellow-orange, C-, KC+ orange-red, P+ orange, UV-. Chemistry: cortex with usnic acid; medulla with the stictic acid syndrome (stictic, constictic, hypostictic and norstictic acids, with traces of cryptostictic and peristictic acids).
Note: a southern species in Europe, found on siliceous boulders, that might be more widespread in Mediterranean Italy. Perhaps better treated as a subspecies of X. conspersa (see Roux & coll. 2014: 1279).