As the third part of the taxonomic review of Cicadidae (Hemiptera, Auchenorrhyncha) from Taiwan, 18 species belonging to six genera in cicadine tribes, Dundubiini (two other genera of Cicadina) and Moganiini, and a tibicinine tribe, Huechysini, are treated in this paper. A new genus, Formocicada Lee and Hayashi, and two new species, Tanna infuscata Lee and Hayashi and Formocicada taiwana Lee and Hayashi, are described. Four species are synonymized: Tanna taikosana Kato, 1925 and Tanna horiensis Kato, 1926 with Tanna taipinensis (Matsumura, 1907), and Tanna horishana Kato, 1925 and Tanna tarowanensis (Matsumura, 1927) with Tanna viridis Kato, 1925. Cryptotympana facialis (Walker, 1858), Cosmopsaltria doryca (Boisduval, 1835), and Leptopsaltria tuberosa (Signoret, 1847) are newly considered as species erroneously recorded from Taiwan. Informations on the biology and male chirpings are also provided.