Basionym Name:Thelidium borreri f. acrustaceum Bagl. & Carestia, Comm. Soc. crittog. Ital. 2(fasc. 2): 326 (1865)
Homotypic synonyms:Thelidium pyrenophorum f. acrustaceum (Bagl. & Carestia) Dalla Torre & Sarnth., Fl. Tirol, Vorarlberg, Liechtenstein, IV Band. Die Flechten von Tirol: 536 (1902)