Zygocactus candidus Lofgren, Arch. Jard. Bot. Rio de Janeiro 2: 30. 1918.
Treated as a synonym of S. microsphaerica by B&T Bradleya 13
Info from B&R (1920)
Type locality: On Itatiaya, Brazil.
Dr. Rose collected this species on the very top of Itatiaya, growing in the shade of rocks (No. 20610) and in the deep cleft of the rock cap through which the ascent to the top is made. Desc from Hunt 2006
Known only from the type, which may have been just a white-flowered form of the species. At the collection site cited by B&R ( Rose 20610) hunt (1995/SPR 4:83) found only plants of S. microsphaerica with purplish pink flower buds (Hunt 6458, 6459; K)