Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Mellāria, ae, f., a city in Hispania Baetica, Plin. 3, 1, 3, § 7
Hence, Mellā-rĭensis, e, adj., of or belonging to Mellaria; in plur. subst.: Mellārĭenses, ĭum, m., the inhabitants of Mellaria, Inscr. Grut. 321, 10.