Lewis & Short

Atarnĕa, ae, f., = Ἀτάρνα, Steph. Byz.; more com. Ἀταρνεύς, a town in Mysia, Plin. 5, 30, 32, § 122.
Hence, Atarnĕus, a, um, adj., of or pertaining to Atarnea, Plin. 37, 10, 56, § 156; cf. Mann. Asia Min. III. pp. 398 and 415.