Synonyms: Arthonia ilicina T.Taylor; Arthonia ilicina Taylor; Arthothelium ilicinum (Taylor) P. James
Distribution: S - Pugl (Durini & Medagli 2002), Cal (Puntillo 1996).
Description: Thallus crustose, endosubstratic creamy white, effuse or delimited by a brown prothalline line. Apothecia arthonioid, scattered, rounded and 0.2-1 mm across, more rarely elongate and c. 0.2-0.6 x 2 mm, 90-130 µm tall, flat and level with thallus or convex and slightly raised, dark red-brown or brown-black, epruinose. Proper exciple poorly developed; epithecium reddish brown, of mainly anticlinally arranged, brown-walled hyphae, 20-25 µm high, K+ olivaceous, often covered with a 10-20 µm high, hyaline, gelatinous layer; hymenium colourless to yellowish brown, 60-85 µm high, K+ pale green, I+ blue turning wine-red; paraphysoids anastomosing, branched in upper part, c. 1 µm thick, the apical cells 1.5-2 µm wide; hypothecum colourless to yellowish brown, 10-30 µm high. Asci 8-spored, broadly clavate, semi-fissitunicate, with a large apical dome, and a distinct ocular chamber, the apex with a K/I+ blue, elongated ring structure and paler bluish tholus flanks, Arthothelium-type. Ascospores 5-6(-7)-septate, hyaline but often turning brown and faintly verruculose when overmature, clavate-obovoid, with one of the terminal cells enlarged, straight to slightly curved, 25-40 x 9-14 µm. Pycnidia brownish, 60-80 µm across, the wall K+ pale green. Conidia bacilliform, 7-9.5 x c. 1 µm. Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a Mediterranean-Atlantic species of humid montane woodlands, known from a few localities in southern Italy. It is included in the Italian red list of epiphytic lichens as “Endangered” (Nascimbene & al. 2013c).
Growth form: Crustose
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)