TYPE. JAPAN. Honshu Province Shinano: Azusayama, Minamisaku-gun. On rocks; elevation about 1400 m, 8.VIII.1959, M. Nuno & S. Kurokawa 59243 (TNS, lectotype; DUKE, US, isolectotypes).
Description.Life form: lichenized fungus.
[Translated and modified from Asahina (1960)] Thallus foliose, adnate, often rosette-forming, up to 4 cm diam.; lobes 1-3 mm wide, +/-0.15 mm thick, dichotomously branched; branches 0.5-1.5 mm wide, +/- overlapping in the center; axils narrow; upper surface grayish white or grayish brown. Vegetative diaspores soredia in soralia; soralia laminal, white, capitate. Lower surface black; rhizines abundant, black, simple. Thallus stratified: upper cortex 12 μm, hyaline; photobiont chlorococcoid alga, cells 6-9 μm diam.; medulla white, hyphae 4 μm thick; lower cortex black, 6-10 μm thick. Ascomata lecanorine apothecia, rare, disk brown, thalline rim flexuose, sorediate. Epithecium brown; hymenium hyaline, 60 μm high; hypothecium + proper exciple 45-50 μm thick. Asci clavate, 50 x 15 μm, I+ blue, 8-spored; ascospores simple, hyaline, ellipsoid, 10-12 x 7 μm. Pycnidia not reported.
Chemistry. Cortex K+ yellow; medulla K+ yellow, PD+ deep yellow; atronorin, galbinic acid, zeorin, leucotylin, secalonic acid A.
Substrate and Habitat. Corticolous on trees.
Distribution. Asian–east North American disjunct; in North Carolina found in the Blue Ridge ecoregion.
Literature
Asahina, Y. (1960) Lichenologische Notizen (§160-163). Journal of Japanese Botany35(4): 97-102 (original description as Parmelia metarevoluta).
Moon, K.H., C. Ahn & H. Kashiwadani (2015) Revision of the lichen genus Myelochroa (Ascomycotina: Parmeliaceae) in Korea. Journal of Species Research4(1): 23-32.