Synonyms: Calicium curtiusculum Nyl.; Calicium decipiens A. Massal.; Calicium lenticulare var. bacillare Ach.
Distribution: N - Lomb (Puntillo & Puntillo 2009), Piem (Isocrono & al. 2004, Puntillo & Puntillo 2009), Emil (Tretiach & al. 2008, Fariselli & al. 2020), Lig (Jatta 1909-1911). C - Tosc (Tretiach & Nimis 1994, Puntillo & Puntillo 2009, Benesperi 2011), Marc (Puntillo & Puntillo 2009), Abr (Nimis & Tretiach 1999, Puntillo & Puntillo 2009), Mol (Nimis & Tretiach 1999, Caporale & al. 2008), Sar (Zedda 2002, 2002b, Puntillo & Puntillo 2009). S - Camp (Garofalo & al. 1999, Aprile & al. 2003b), Pugl (Thüs & Licht 2006), Bas (Nimis & Tretiach 1999, Puntillo & Puntillo 2009), Cal (Puntillo 1994, 1996, Puntillo & Puntillo 2009).
Description: Thallus crustose, episubstratic, rather thick, minutely granular, grey-green. Apothecia long-stalked, pin-like, black, but white-pruinose on the edges and lower side of capitulum. Stalk black, matt, medium brown in section, (0.5-)0.8-1.3 mm high, of sclerotized, densely and irregularly interwoven hyphae. Capitulum lenticular, with a well-developed, cup-shaped exciple of anticlinally arranged cells; mazaedium well developed, black; hypothecium medium brown, with a slightly convex upper surface. Asci cylindrical, formed singly, dissolving early, with uniseriately to rarely biseriately arranged ascospores. Ascospores 1-septate, dark brown, ellipsoid, 9-13 x 4-6 µm, with a thick, ornamented wall, the ornamentation of minute, spirally arranged ridges and irregular cracks. Photobiont chlorococcoid. Spot tests: thallus K+ yellow then red, C-, KC-, P+ yellow; ascomata I- in all parts. Chemistry: thallus with norstictic acid.
Note: a holarctic, temperate species found on lignum and bark of deciduous trees, more rarely of conifers, especially on old oaks and Castanea, certainly occurring throughout the Alps.