Discovery of a new species of Trapelia and one of Ainoa prompted a taxonomic revision of saxicolous, esorediate members of the genera Ainoa and Trapelia that occur in North America north of Mexico. In addition to the description of A. bella and T. stipitata, both from eastern North America, revised descriptions and distributions are presented for T. coarctata and T. glebulosa. All of the species are illustrated, and A. mooreana (syn. T. mooreana) is excluded from the North American checklist.