TYPE. Not cited. Original treatment (Michaux 1803): "Hab. Arboricola in Canada et Carolina."
Description. Lichenized fungus.
Thallus foliose, uniformly pale gray; lobes 2-8 mm wide, sometimes divided into narrow lobes; marginal cilia black, scattered; vegetative diaspores absent. Lower surface black with broad brown naked zone under edges; rhizines black, simple, abundant in center, absent near lobe tips. Photobiont chlorococcoid alga. Ascomata lecanorine apothecia, flat to bowl-shaped, unperforated, up to 8 mm diam. Disk concave, brown. Pycnidia black, abundant on lobe tips; conidia hyaline, simple, straight, rod-shaped, 5.5-6.5 μm long.