This name is a synonym of Phlox kelseyi subsp. variabilis (Brand) Wherry.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50130902) with original publication details: Pflanzenr. 27[IV,250]: 87 1907.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:193713-2.
This name was in version 1 of The Plant List, record tro-50130902.