A Truly Rare Cactus Borne In My Collection - Pediocactus Knowltonii Crest !

? Pediocactus Knowltonii Crest ?

** UPDATE *** 3/3/14

THIS PLANT MAY IN FACT HAVE BEEN IDENTIFIED WRONG. POSSIBLE ID
Echinocactus Grusonii Variant Alba Inermis Crest

I planted the seed for this plant about 5 years ago, the germination rate was terrible from 20 seeds a single seedling germinated. I grafted the seedling to Hylocereus and after a few weeks I knew I had a special plant;

I have done a fairly extensive search of the web and spoken to everyone I know in the cacti industry and I can't find another plant in a collection anywhere, it could possibly be a truly unique plant. Over the last few years it has grown well;

About 1.5 years ago I did a semi degraft and potted the plant up to grow on it's own roots with the assistance of the Hylocereus whilst is establishes itself;

Before De-graft

Today

Today I took the knife out and have cut this plant up in an attempt to propagate this beauty and one day distribute it out to the cacti community :) I will post up some pics later on.