Slow growing plant of uncertain identity.

Plant grown from seed obtained from a specialist supplier in 1986.Flowers approx. 3.5cm.long and diameter are produced in spring and remain open for about three or four days.

Not thought to be a Neoporteria as flowers open fully. If you may be able to identify this plant please let me know.

Kept slightly moist in winter at a minimum temperature of 45 - 50degrees F.