Lewis & Short

Tarquĭtĭus, ii, m., an Etruscan proper name; so esp. the Etruscan Tarquitius, who wrote on divination, Macr. S. 3, 7, 2; Lact. 1, 10, 2; Plin. ind. libri 2.
Hence, Tar-quĭtĭānus, a, um, adj., of Tarquitius: libri, Amm. 25, 2, 7.