Acta Soc. Fauna Fl. Fenn. 4: 137 (1887).

Basionym: Scyphophorus didymus Fée, Essai Crypt. Ecorc.: cxviii, ci. (1825).

Type locality: Dominican Republic ("Santo Domingo"), D. Poiteau s.n. (G - lectotype; G, PC-Mont, UPS - isolectotypes).

Taxonomy: Specimens from the Azores are nesting together with eastern North American samples Pino-Bodas et al. 2017: 450 based on ITS data).

Note: The variety Cladonia didyma var. vulcanica is here treated in the species rank Cladonia vulcanica.