This name is a synonym of Dendrobium gracilicaule var. howeanum Maiden.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 58319) with original publication details: J. Arnold Arbor. 67: 115 1986.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:952282-1.
This name was in version 1 of The Plant List, record kew-58319, and has not been changed.