Synonyms: Calicium schaereri De Not. non auct.; Chaenotheca albida (Körb.) Zahlbr.; Chaenotheca schaereri (De Not.) Zahlbr.
Distribution: N - Ven (Puntillo & Puntillo 2009), Lomb (Anzi, Lich. Rar. Langob. Exs. Nr. 204: S-L30504).
Description: Thallus crustose, episubstratic, granular-verrucose, grey-white, more rarely almost endosubstratic and poorly evident. Apothecia short-stalked, pin-like, 0.6-1 mm high. Upper part of stalk dark, but covered in a thick white pruina, lower part pale brown to almost white. Outermost layer of stalk hyaline, consisting of periclinally arranged, strongly gelatinized hyphae: Capitulum 0.2-0.4 mm across, obovoid to obconical, with a well-developed excipulum; inner part of excipulum consisting of periclinally arranged, medium brown hyphae, outer part of irregularly intertwined, swollen and sclerotized hyphae; lower side of excipulum white-pruinose, edge often with irregular vertical splits. Mazaedium well-developed, brown; hypothecium pale brown to colourless, with a concave upper surface. Asci ellipsoid or irregular, formed in chains from hooked ascogenous hyphae, dissolving early, with uniseriate ascospores. Ascospores 1-celled, brown, globose, 4.5-5.5 µm wide, the wall smooth or with irregular cracks. Photobiont chlorococcoid, with rectangular cells (Stichococcus). Spot tests: thallus K-, C-, KC-, P-. Chemistry: thallus with very low amounts of atranorin and other unidentified substances.
Note: a mild-temperate species found on the nutrient-rich bark of several trees (e.g. Acer, Fraxinus, Populus, Ulmus), in deep fissures of the bark seldom wetted by rain, with optimum at low elevations. It is included as “Regionally Exctinct” in the Italian red list of epiphytic lichens (Nascimbene & al. 2013c).