Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Titūrĭus, ii, m., a legate of Cæsar in the Gallic war, Caes. B. G. 5, 27; 5, 29; 5, 33; Suet. Caes. 25.
Hence, Tĭtūrĭā-nus, a, um, adj., of Titurius, Titurian: clades, Suet. Caes. 67.