N. Amer. Fung., 7, 2: 3, 2012. Basionym: Parmelia crozalsiana B. de Lesd. ex Harm. - Lich. de France, 4: 555, 1910.
Synonyms: Canoparmelia crozalsiana (Harm.) Elix & Hale; Parmotrema crozalsianum (Harm.) D. Hawksw.; Pseudoparmelia crozalsiana (Harm.) Hale
Distribution: N - Lig (Castello & al. 1994, Brunialti & Giordani 2000, 2003, Giordani & al. 2001, Giordani & Incerti 2008). C - Laz (TSB 17670). S - Si (Ottonello & al. 1994, Iacolino & Ottonello 2006).
Description: Thallus foliose, adnate, sorediate, 3-6(-10) cm across. Lobes irregularly rounded, 3-5(-8) mm wide, grey to dark grey, reticulately ridged to slightly rugose, emaculate of faintly maculate, shallowly foveolate, epruinose or rarely slightly pruinose especially along the margins, cracked in older parts, with laminal, often capitate soralia developing along ridges and cracks; soredia white, granular to farinose. Medulla white, also under the soralia. Lower surface black in central parts, with simple, black, to 1.5 mm long rhizines; marginal parts brown, erhizinate. Apothecia extremely rare, lecanorine. Asci 8-spored, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid. Pycnidia very rare, black. Conidia thread-like. Photobiont chlorococcoid. Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow; medulla K+ yellow-red, C-, KC-, P+ orange. Chemistry: chloroatranorin, atranorin, stictic, constictic and cryptostictic acids.
Note: a mild-temperate species with subtropical affinities, also reported from North America, locally abundant only - and strangely - in Liguria (especially in Olea-plantations), but also sporadically occurring in other warm-humid areas of Tyrrhenian Italy. It is included in the Italian red list of epiphytic lichens as “Endangered” (Nascimbene & al. 2013c). See also note on C. carneopruinata.
Growth form: Foliose, broad lobed
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)