Niobeus
Could not find Niobea in Logeion dictionaries.
Niobea proper-name adjective neuter nominative plural, proper-name adjective neuter vocative plural, proper-name adjective feminine nominative singular, proper-name adjective feminine ablative singular, proper-name adjective feminine vocative singular, proper-name adjective neuter accusative plural of Niobeus
Nĭŏbēus, (16) a, um, de Niobé : Hor. O. 4, 6, 1 || -bĭdēs, æ, m. , fils de Niobé : Hyg. Fab. 11.