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Caloplaca fulvolutea (Arnold) Jatta
Family: Teloschistaceae
Caloplaca fulvolutea image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus grayish white, on Grimmia species, scarcely visible. Apothecia numerous, loosely attached, moderately convex, round, 0.5-0.8(-l .2) mm broad, base narrowed; margin thick, or becoming thin, persistent; disk flat to somewhat concave, yolk-yellow, seldom orange-yellow or olivish, lower side often graying; cortical tissue paraplectenchymatous, radiating toward margin; hymenium 90 µm; paraphyses to 4 µm at tips, which are in a moderately granular episamma; spores 8, often less, broadly ellipsoid to nearly rhombic, 15.5-18.5 x 8-9 µm, septum 1.5-3 µm, outer wall well defined.

This species appears to be nearly confined to species of Grimmia in acid habitats. It is arctic-alpine, known from Europe and western Greenland on Disko Island and the nearby Umanak region (Hansen, Poelt, & Sochting 1987).

This species resembles C. jungermanniae but is distinguished by its habitat, the smaller and more yolk-yellow apothecia, the shorter spores with earlier development of septum, and the clearly distinguished outer spore wall.