New area bosses? I don't think so.

"Nona" is latin and means "the ninth".

And, as already said, the fox with nine tails does not have its origins in Naruto.

Tons of Japanese media have nine tailed foxes in them. Others have foxes with other amounts of tails. The mythos is that the more tails it has, the more mystical it is or something. Notice that Miles "Tails" Prower of Sonic the Hedgehog fame is a fox with two tails.