Synonyms: Ochrolechia erichsenii auct. non Hafellner & Türk; Pertusaria tumidula auct. non Erichsen?
Distribution: N - Lig (Giordani & Brunialti 2000). C - Tosc, Sar (Kukwa 2011). S - Cal (Puntillo 1996), Si (Grillo 1998, Grillo & Caniglia 2004, Kukwa 2011).
Description: Thallus crustose, episubstratic, to 2 mm thick, whitish, grey-white or beige, verrucose-areolate, sorediate. Areoles wart-like, strongly convex to subglobose, often constricted at base, contiguous, with irregular, convex, often confluent, externally pale brownish-grey to brown, internally greenish-grey soralia bearing granulose soredia. Apothecia lecanorine, up to 5 mm across, round to irregular in outline, with a pruinose, concave, almost punctiform disc and a distinct, pruinose parathecial ring which are largerly hidden by a thick, prominent pruinose, sometimes sorediate thalline margin. Proper exciple well-developed, up to 300 µm thick; epithecium pale brown, with crystals; hymenium colourless, up to c. 150 µm high; hypothecium colourless. Asci 8-spored with thick, amyloid walls, Pertusaria-type. Ascospores 1-celled, hyaline, ellipsoid, 60-70 x 40-50 µm. Photobiont chlorococcoid. Spot tests: epithecium, soredia, thalline margin and medulla of apothecia K-, C+ red, KC+ red, P-; medulla of thallus C-, KC-. Chemistry: gyrophoric and lecanoric acids; apothecia with additional alectoronic acid.
Note: a rare, Mediterranean silicicolouos species known from France, Italy and perhaps the Iberian Peninsula; it is related to O. tartarea, but is morphologically and chemically different, and has a montane-Tyrrhenian distribution in Italy.
Growth form: Crustose
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)