This name is a synonym of Achillea santolinoides subsp. wilhelmsii (K.Koch) Greuter.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record 3FC2B836-4B13-400F-8CB6-AC8D1A9648DF).
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 Achillea wilhelmsii in version 1 of The Plant List.