Magnusson, A.H. 1944. Some species of Caloplaca from North America. Botaniska Notiser 1944: 63-79.
From page 70:
“Thallus pallidus vel albescens, effusus, tenuis, granulatus. Apothecia sessilia, ± crebra, minuta, disco rufo-ferrugineo, plano vel leviter convexo, margine tenui concolori subdepresso cincto, gonidiis destitute. Thecium angustum, superne fusco-aurantiacum. Paraphyses conglutinatae, superne haud incrassatae. Sporae haud evolutae.
Granules 0.1-0.15 mm large, constricted at base, contiguous or crowded, KOH-. Apothecia 0.5-0.7 mm, orbicular, prominent, about 0.25 mm thick, without gonidia.
Exciple at edge and base 35-50 μ thick, refracting, hyphae perpendicular, gelatinous, cells ± cylindric. Hypothecium 20-25 μ, pale brownish orange like thecium, I ± blue, below it 100 μ thick medulla, dark brownish yellow, opaque from granules, in KOH transparent, dark yellow. Thecium 50-55 μm I + blue; upper 17 μ pale brownish orange, diffuse, in CaCl more violet, in KOH violet red. Paraphyses conglutinate, also in KOH, cells cylindric, 1 μ. Only young, narrow asci seen without spores.
Habitat. On oak tree.
Locality. N. Carolina: Tryon 1927 Alex. W. Evans (411) hb Mn. [specimen at YPM: https://lichenportal.org/portal/collections/individual/index.php?occid=1654759&clid=0].
Distinguished from real ferruginea [Blastenia ferruginea] by the distinct and minutely granular thallus, the faintly prominent apothecial margin and the thin, colored thecium."