This name is a synonym of Phlox speciosa subsp. occidentalis (Durand ex Torr.) Wherry.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50122810) with original publication details: Proc. Acad. Nat. Sci. Philadelphia 3: 97 1855.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:193444-2.
This name was in version 1 of The Plant List, record tro-50122810.