This name is a synonym of Sphaerostigma tortum (H. Lév.) A. Nelson.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50107686) with original publication details: Monogr. Onothera 230 1905.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:172862-2.
This name was in version 1 of The Plant List, record tro-50107686, and has not been changed.