Bacidia coprodes (Körb.) Lettau, until now treated as a synonym of Bacidia trachona (Ach.) Lettau, is resurrected. Morphological, chemical and ecological characteristics place this species close to Toninia in the Ramalinaceae, but we retain it in Bacidia because of uncertainties in the generic taxonomy of this family. Bacidia coprodes is fairly widespread on calcareous and enriched siliceous rock in Europe and eastern North America. In North America the species has also been known under the synonyms Bacidia granosa (Tuck.) Zahlbr. (basionym: Lecidea granosa Tuck.) and Bacidia pammellii (Fink) Zahlbr. (basionym: Bilimbia pammellii Fink). Morphological and chemical features, together with molecular data, suggest that B. trachona does not belong to Bacidia, but rather in the Pilocarpaceae.