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Rhizocarpon viridiatrum (Wulfen) Korber
Family: Rhizocarpaceae
[Buellia viridiatra (Wulfen) H. Olivier,  more]
Rhizocarpon viridiatrum image
Life habit: lichenized, initially lichenicolous, later growing free Thallus: crustose, immersed in the host thallus or areolate; prothallus: absent to well developed areoles: round to angular, plane to weakly convex, up to 0.6 mm in diam. surface: greenish yellow, smooth, epruinose medulla: KI+ faintly violet Apothecia: round or angular, up to 0.8 mm in diam. disc: black, weakly or strongly convex, epruinose margin: lacking exciple: with black margin epihymenium: brown, K+ red, not containing crystals hymenium: hyaline, 85-140 µm tall; paraphyses: clavate; hypothecium: brown asci: clavate, 8-spored ascospores: black, submuriform, ellipsoid, 12-25 x 7-13 µm Spot tests: medulla K+ yellow, C-, P+ orange Secondary metabolites: rhizocarpic, norstictic (minor) and stictic (major) acids. Substrate and ecology: on non-calciferous to somewhat calciferous rock, often sandstone, in open situations in coniferous regions at 1050-2990 m, uncommon Host: Acarospora and Aspicilia World distribution: Africa, Australasia, Europe, North America, and South America Sonoran distribution: Arizona and southern California.