Thallus: composed of minute warts areoles: irregular in outline, moderately to strongly convex, sometimes marginally incised, 0.05-0.3 mm in diam. surface: greenish gray to pale ochre, dull, esorediate cortex: poorly developed, hyaline, 5-10 µm thick medulla: mostly lacking; algal layer: 70-100 µm thick Apothecia: rounded to somewhat deformed, sessile with a constricted base, 0.35-0.8(-1.1) mm wide disc: reddish brown to brown-black, initially concave, soon plane or weakly convex margin: same color as disc or paler outside, persistent or excluded in older apothecia exciple: brown in upper parts or near hymenium, usually lighter brown or almost hyaline below, laterally 50-80 µm, basally 95-250 µm wide, composed of radiating hyphae with 1-4.5 µm to apically 2-6.5 µm wide lumina epihymenium: orange brown or red-brown, 5-15 µm high, often poorly delimited against hymenium hymenium: hyaline, sometimes with pale brown stripes, rarely with blackish blue granules of "hypnorum-blue", 55-75 µm tall; paraphyses: hyaline or pale brown at the apices, below 1-2 (-3) µm wide to apically 1.5-4.5(-6.5) µm wide lumina, weakly branched and anastomosing subhymenium: often darker than hypothecium, rarely with blackish blue granules of "hypnorum-blue" (Meyer and Printzen 2000) hypothecium: brown; hypothecium and subhymenium: together 175-270 µm thick asci: clavate, ±Porpidia-type, with a I+ blue tholus containing a distinct darker blue tube structure in the center, 8-spored ascospores: hyaline, simple, fusiform-ellipsoid, (8.5-)10.4-14.8(-16.5) x (3.8 )4.4-5(-5.5) µm; walls: often with a rough perispore 0.5 µm wide Pycnidia: not seen. Spot tests: thallus K-, C-, KC-, P- Secondary metabolites: none detected by TLC. Substrate and ecology: on bryophytes over rock and soil between c. 600 and 3350 m World distribution: circumpolar in boreal regions of the Northern Hemisphere Sonoran distribution: Arizona and southern California. Notes: In Sonoran specimens the thallus is rather thin and brittle compared with European material. So far Lecidea berengeriana is the only muscicolous/ terricolous Sonoran species of Lecidea s. lat. Mycobilimbia carneoalbida and M. tetramera can be similar in outward appearance, but are distinguished by having 3-septate spores, narrower paraphyses and excipular hyphae and a paler hypothecium. Mycobilimbia olivacea has a similar ascus type and spores, but it grows on wood and bark and is readily distinguished by its dark green, subsquamulose thallus, ±emarginate apothecia, and its hyaline hypothecium.