This name is a synonym of Hieracium lachenalii subsp. festinum (Boreau) Zahn.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym (record F3539C41-CA9E-496D-8849-779C4A532C82) with original publication details: 399 1857.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:224441-1.
This name was in version 1 of The Plant List, record gcc-84953, and has not been changed.