Synonyms: Buellia epigaea var. angusata (Müll. Arg.) Zahlbr.; Buellia epigaea var. effigurata (Schaer.) Zahlbr.; Buellia epigaea var. major (Müll. Arg.) Zahlbr.; Diploicia epigaea var. angustata Müll. Arg.; Diploicia epigaea var. effigurata (Schaer.) Körb.; Diploicia epigaea var. major Müll. Arg.; Lecidea epigaea var. effigurata Schaer.
Distribution: N - Lomb (Trinkaus & Mayrhofer 2000), Piem (Hafellner & al. 2004), VA (TSB 29482).
Description: Thallus crustose-placodioid, episubstratic, of radiating, white-pruinose, 1-2 cm long, 0.3-1.2 mm wide lobes, forming orbicular to irregular, up to 4 cm wide rosettes. Cortex c. 20 μm thick, filled with crystals; medulla white, I-; lower surface pale, attached with rhizohyphae. Apothecia not always present, lecideine, 0.6-1.8 mm across, at first immersed but soon becoming adnate, with a black, flat to slightly convex, soon epruinose disc, and a thin, black, often pruinose, persistent proper margin; a pseudothalline margin is sometimes present at the base of the proper margin. Proper exciple dark red-brown in outer part, paler within; hymenium colourless, not inspersed with oil droplets, 70-150 μm high, I+ blue; paraphyses 1-1.5 μm thick at mid-level, the apical cells 4-5 μm wide, with a brown cap; hypothecium black-brown to black-grey. Asci 8-spored, clavate, Bacidia-type. Ascospores 1-septate, slightly constricted at septa, brown, oblong-ellipsoid, 12-22 x 5.5-10.5 μm, with a thin, minutely warted wall. Pycnidia black. conidia bacilliform, 5-8 x 1-1.5 μm. Photobiont chlorococcoid. Spot tests: cortex K+ yellow (reaction sometimes faint), C-, KC-, P-; medulla K-, P-, or K+ red, P+ orange-red in spots. Chemistry: cortex with atranorin; medulla sometimes with norstictic and stictic acids.
Note: a widespread steppe-species found on soil deriving from calciferous schists in open grasslands, restricted to dry-warm sites in the Alps.
Growth form: Crustose placodiomorph
Substrata: soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)