Date: 2002 May 19
You might also find this plant under Mediolobivia, Aylostera, and possibly several other genera. I've also seen it classified as a variety of Rebutia einsteinii.
Despite all this, it is a most distinctive plant, but the stems tend to elongate more in cultivation than is said to happen in habitat (see John Pilbeam's article, Journal of the British Cactus & Succulent Society, No. 1 Vol. 20 March 2002, page 19).
My plant was obtained from Abbey Garden nursery in Carpinteria, California,
in 1981. I originally found it difficult to grow on its own (tuberous) roots,
and grafted it. This flowering specimen is grafted on Trichocereus,
but more recently I have rooted several pieces.