Distribution: N - Frl (Tretiach 2004), Ven (Nascimbene & Caniglia 2000), TAA (Caniglia & al. 2002, Nascimbene 2005b, 2006c, Nascimbene & al. 2022), Lomb (Nascimbene 2006), Piem (Matteucci & al. 2013), VA (Piervittori & Isocrono 1999), Emil (Tretiach & al. 2008, Fariselli & al. 2020), Lig (Brunialti & al. 1999). C - Tosc (TSB 34222). S - Bas (Potenza & al. 2014), Cal (Puntillo 1995, 1996, Potenza & al. 2011).
Description: Thallus minutely filamentous, forming mats or small tufts on the rock, consisting of c. 10 µm thick, irregularly arranged, black, knobbed, sometimes shortly branched (at right angles) filaments. Filaments covered with dark-brown, tortuous, branched, brown-pigmented hyphae with irregularly undulate walls, forming a dense network closely surrounding and adhering to single filaments of Trentepohlia. Apothecia and pycnidia unknown. Photobiont trentepohlioid. Spot tests: all negative. Chemistry: without lichen substances.
Note: a cool-temperate to boreal-montane, probably holarctic lichen found on vertical to underhanging surfaces of siliceous rocks protected from rain in very humid situations, more rarely on soil. The species often grows mixed with Racodium rupestre, forming black, felt-like patches over extensive areas of rock; the most commonly associated lichens are species of Lepraria; much overlooked, and certainly more widespread, at least in the Alps.
Growth form: Crustose
Reproductive strategy: mainly asexual, by thallus fragmentation
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)