Echinopsis subdenudatum 'fuzzy navel'.
Ok, I'll ask as no one else is going to. Why "Fuzzy Navel"? Now I have to go out and stare at my spineless white blooming Echinopsis and wonder if it has a fuzzy navel. (a little more personal then I care to get).
I think if you look at the buds of any other Echinopsis you will find that they are really fuzzy too, but what makes E. subdenudatum stand out from other Echinopsis is that its aureoles, where the buds form, are much more hairy/fuzzy.
In my collection of Echinopsis plants and hybrids (up to about 80-90 now) the only two that come close in fuzziness of the aureoles are two subdenudatum hybrids. There are some others with hairy aureoles, just not quite so obvious as 'Fuzzy Navel'.
Wrong photo. This is the'fuzzy navel' getting ready to bloom.