@Ksunder
It's the name of Ariane's parents' village. Elves take the name of their place of residence. Ariane moved to the capital, Maple, when she joined whatever elite unit she's in, so she's "Ariane Glenys Maple". (The middle name comes from a parent's name.) She was Ariane Glenys Lalatoia before that.
Arc being told to call himself "Arc Lalatoia" means he's been accepted not just as a temporary guest, but an actual resident.