Red spined Mamm carmenae. (rubra)

What is the correct name for this plant?
They call it carmenae but I'm not convinced. It's spines are much more  stiff than carmenae. If it's a hybrid, what species are involved?

Hi Mike,
The usual hybrids with carmenae are lauii, but those don't contribute red spines. I don't know what is used, but I wonder it could be elongata, another species with variable spine colour. It could just be that a nursery somewhere producing lots of plants for the retail market has come across the odd red spined plant and selectively propagated it into a cultivar strain.

Thanks Chris. Yes lauii and I would suspect subducta is a a prime contender.

I have held off ordering carminae red spined versions, I'm not sure if they exist in the wild and havent seen any with collection numbers attached. Could be a selection but the coarseness of the spines makes me wonder if it (and they) are hybrid.