I can't remember who makes it, but there is at least one commercial example of a Black IPA out there.
Regardless.... call it whatever you want! Unless you are entering competitions, it really doesn't matter that you adhere to any particular style guidelines.
edit: even if you go by style, the top range of color for an IPA is 15 SRM from what I am reading right now.
My own IPA recipe is about 6 SRM (the low end of the PA scale) and if I add 0.5# of chocolate malt to it, it just BARELY goes to 18 SRM. Not very far out of bounds.