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 277172) with original publication details: J. Linn. Soc., Bot. 18: 202 1880.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:536071-1.
This name was in version 1 of The Plant List, record kew-277172, and has not been changed.