You're right.. It's not a true P. Hystrix. If it was, with the Export ban out of Brazil, it would probably cost alot more too!
It is the Peruvian Motoro variant, which the farmers in Peru call 'Histrix.' I have seen other Vendors promise true Hystrix rays to people, only to fulfill the orders with these fakes. I have got a ton of them before, all with slightly different patterns. So I am %100 positive it is not a true Hystrix, and it is a Peruvian Histrix.
The primary reason that the vendors keep the name 'Hystrix' on these rays is for the simple fact they can fool the buyer into thinking it will stay a small size.. Unfortunately this ray will still grow to be 18-22" across!
Hope that helps!
Nice Motoro sp. "Peru" otherwise, I like the 'eyebrows' above his eyes.