Once again you show some interesting plants in your A-Z.
Personally, I see no significant differences from other members of the Supertextae to warrant separate status of m.gieseckei. Chris Davis's and " Ento's " plants look no different from plants I have which are labelled m. supertexta. Plants with tight white spines and copious amounts of wool in their axils. Your plant, with it's yellowish central spines, is different from their's, but no different from a m. flavicentra type. I think m. gieseckei is just another new plant name introduced by collectors to sell more plants and seed.