Lewis & Short

Ămȳthāōn (also Ămĭth-), ŏnis, m., = Ἀμυθάων, a Greek, the father of Melampus, Ov. M. 15, 325.
Hence, Ămythāŏ-nĭus, a, um, of Amythaon, Verg. G. 3, 550; Prop. 2, 4, 10.