Synonyms: Lecidea elaeochroma var. muscorum Th. Fr.; Lecidea glomerulosa var. muscorum (Th. Fr.) Vain.; Lecidea heppii R.A. Anderson & W.A. Weber; Lecidea muscorum (Th. Fr.) Dalla Torre & Sarnth.; Lecidea wulfeniana Grummann; Lecidea wulfenii (Hepp) Arnold
Distribution: N - Frl (Tretiach & Hafellner 2000), Ven (Nascimbene & Caniglia 2003c, Nascimbene 2008c), TAA (Bilovitz & al. 2014b), Lomb, Piem (Isocrono & al. 2004), VA (Valcuvia 2000), Lig. C - Abr (Gheza & al. 2021, Di Nuzzo & al. 2021). S - Bas (Nimis & Tretiach 1999).
Description: Thallus crustose, whitish to pale yellowish grey, thin, continuous or coarsely granular-papillate to verrucose. Apothecia lecideine, black, round, sessile and constricted at base, 0.3-1.5 mm across, with a flat to finally convex, usually epruinose disc, and a smooth, often glossy, sometimes crenate-undulate, finally often excluded proper margin. Proper exciple dirty bluish-black in outer part, reddish within; epithecium dark greenish blue to blue-black, K-; hymenium colourless to pale greenish blue in upper part, 70-100 µm high, not inspersed with oil droplets; paraphyses easily made free in K, mostly simple, slightly thickened at apex; hypothecium brown, paler in upper part. Asci 8-spored, clavate, with an intensely I+ blue tholus penetrated by a weakly amyloid, broadly cylindrical axial mass, and a poorly developed ocular chamber, Lecidella-type. Ascospores 1-celled, hyaline, broadly ellipsoid, rather thick-walled, 7-16(-18) x (5-)7-8(-9) µm. Pycnidia dark, globose, immersed. Conidia thread-like. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C+ weakly orange, KC+ yellow-orange, P+ pale yellow or P-. Chemistry: thallus with 2,5,7-trichloro-3-O-methylnorlichexanthone, 5,7-dichloro-3-O-methylnorlichexanthone, atranorin, isoarthothelin, or thiophanic acid.
Note: a circumpolar, arctic-alpine lichen found on muribund bryophytes and plant remains in exposed habitats near and above treeline; most common in the Alps, but also present in the high mountains of southern Italy. For the chemistry see Knoph & Leuckert (1997).
Growth form: Crustose
Substrata: soil, terricolous mosses, and plant debris