Question about the new update bosses

Do the new bosses use the general themes for the areas they reside in, or do they possess a unique boss music? Or even if the prior were not true, do they use a boss theme in existence?

I'd just think it'd be awesome to fight 'em using the theme that was used against the first Cygnus boss, or even have their own unique theme.

Anyone finished the quests up to that point?