Synonyms: Parmelia scortella auct. non Nyl.; Parmelinopsis minarum (Vain.) Elix & Hale
Distribution: N - TAA (Nascimbene 2006c, Nascimbene & al. 2007b, Masson 2005), Lig (Masson 2005). C - Marc (Nimis & Tretiach 1999), Abr (Nimis & Tretiach 1999, Corona & al. 2016).
Description: Thallus foliose, heteromerous, dorsiventral, rather loosely appressed, forming up to 8 cm wide, irrregular, more or less compact rosettes. Lobes irregularly branched with rounded axils, elongate, contiguous to imbricate, (0.5-)1-3(-5) mm wide, with truncate ro subrotund, crenulate tips, apparently with to 0.7 mm long, black marginal cilia (actually projecting rhizines). Upper surface pale ash-grey, sometimes slightly glaucescent, rarely browned at margins, smooth, emaculate, rather shiny; isidia dark grey, simple to branched-coralloid, eciliate or with very short cilila visible only at high magnification, sometimes apically browned. Lower surface black in central parts, brown at margins, slightly shiny, with simple to irregularly branched, black rhizines which often project beyond lobe margins. Upper cortex of tightly packed, anticlinally oriented hyphae, with a pored epicortex, the cell walls with isolichenan; medulla white; algal layer continuous; lower cortex brown, of anticlinally oriented hyphae. Apothecia very rare, lecanorine, 1-5 mm across, with a dark brown disc and an isidiate thalline margin. Epithecium brownish; hymenium and hypothecium colourless. Asci 8-spored, clavate, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 10-17 x (5-)8-10 µm. Pycnidia rare, laminal, immersed. Conidia cylindrical. Photobiont chlorococcoid. Spot tests: upper cortex K+ yellow; C-, KC-, P-; medulla K- or K+ pink, C+ pink, KC+ pink-red, P-, UV-. Chemistry: upper cortex with atranorin and chloroatranorin; medulla with gyrophoric acid (major), lecanoric acid (minor), and related accessory substances (hiascic, 4,5-di-0-methylhiascic, 4-0-methylhiascic acids).
Note: a mainly tropical species, also occurring in Western Europe and in the most humid parts of the Alps, on trees, more rarely on mossy siliceous rocks in old, humid forests. See also note on H. horrescens.
Growth form: Foliose, broad lobed
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)