This name is a synonym of Haworthia coarctata f. greenii (Baker) M.B.Bayer.
The record derives from WCSP
(data supplied on 2012-03-26)
which reports it as a synonym (record 277059) with original publication details: Natl. Cact. Succ. J. 28: 86 1973.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:886291-1.
This name was in version 1 of The Plant List, record kew-277059, and has not been changed.