This name is a synonym of Phlox drummondii subsp. johnstonii (Wherry) Wherry.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50229545) with original publication details: Wrightia 2(4): 198–199 1961.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:193526-2.
This name was in version 1 of The Plant List, record tro-50229545, and has not been changed.