The validity of the subspecies are not widely recognized. Endemic to the Aru Islands, this subspecies are described to be slimmer and have longer neck.
Was this bird labeled as aruensis, or is that your own identification? This is one of the "violet" eclectus, probably vosmaeri if pure, but definitely not an aruensis which have deep blue underparts and a blue eye-ring.
@Chlidonias atleast Mistake in IDing I guess, I've used several sources in the internet, including local Indonesian ones, and aruensis seems to be shown like this in some sources. I though it was vosmaeri earlier since the bird have a lot of purple, though this bird doesn't really have a bright yellow tail-edge, so I guess a hybrid (?).