Synonyms: Arthopyrenia farrea auct. non (Ach.) H. Olivier; Leptosphaeria leucoplaca (Wallr.) Vain.; Porina chiomela (Norman) Zahlbr.; Pyrenula alba A. Massal.; Pyrenula alni A. Massal.; Pyrenula farrea auct. non (Ach.) Branth & Rostr.; Pyrenula leucoplaca (Wallr.) Körb.; Pyrenula quercus A. Massal.; Pyrenula schaereri A. Massal.; Spermatodium leucoplacum (Wallr.) Trevis.
Distribution: N - VG (TSB 5622), Ven (Lazzarin 2000b), TAA (Nascimbene & al. 2007b, 2014, Nascimbene 2014), Emil (Fariselli & al. 2020), Lig. C - Umb (Ravera 2000, Ravera & al. 2006), Laz (Ruisi & al. 2005), Abr (Caporale & al. 2016, Gheza & al. 2021), Mol (Paoli & al. 2015). S - Pugl (Nimis & Tretiach 1999), Bas (Ravera & al. 2015d), Cal (Puntillo & Puntillo 2004), Si (Grillo & Cristaudo 1995).
Description: Thallus crustose, immersed in the bark, smooth, continuous, white to pale grey. Perithecia 0.2-0.35 mm across, black, protruding, hemispherical or often somewhat flattened at the top. Involucrellum clasping the centrum; exciple black in upper part, colourless at the base; hamathecium of numerous, simple, persistent paraphysoids. Asci 8-spored, subcylindrical, without apical ring-structure and without a distinct ocular chamber, the wall K/I+ blue, especially in lower part. Ascospores 5-6-septate, not constricted at septa and with rectangular loculi, brown, thin-walled, (13-)18-26(-32) x (4-)6.5-10(-12) µm, the two apical cells paler than the others, the central cell larger and darker. Pycnidia black, immersed. Macroconidia brown, (0-)1-septate, ellipsoid to pyriform, 6.5-9.5 x 3-4 µm; microconidia colourless, thread-like, 6-10 x 0.5-0.7 µm. Photobiont trentepohlioid. Spot tests: all negative. Chemistry: without lichen substances.
Note: a temperate species found on the (mostly) smooth bark of deciduous trees in open, humid forests; probably more frequent in the past. It is included in the Italian red list of epiphytic lichens as “Near-threatened” (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)