This name is a synonym of Sedum wrightii var. densiflorum (R.T. Clausen) H. Ohba.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50314282) with original publication details: Variat. Sp. Sedum Mex. Cordill. Plateau 13 1981.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:231923-2.
This name was in version 1 of The Plant List, record tro-50314282, and has not been changed.