This name is a synonym of Agave mitis var. albidior (Salm-Dyck) B.Ullrich.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 293569) with original publication details: Hamburger Garten- Blumenzeitung 21: 256 1865.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:6350-2.
This name was in version 1 of The Plant List, record kew-293569, and has not been changed.