Coryphantha greenwoodii?

[tacrolimus]

Hello all.
I have a problem of identification with the cactus pictured below (sorry no flower) and i'd like to ask for your help.
This cactus was listed as Coryphantha greenwoodii by the seller.
I learned that this is actually a synonym of Coryphantha elephantidens greenwoodii.
Besides this detail, do you believe that the classification is correct or not?

Thank you
Regards
Luigi