This name is a synonym of Symphyotrichum ontarionis (Wiegand) G.L.Nesom.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 9EC1AC03-63D8-4533-B190-C8EF6DE0D6E8) with original publication details: 1996.
This name record (from TICA) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Aster ontarionis in version 1 of The Plant List.