This name is a synonym of Carduus nigrescens subsp. vivariensis (Jord.) Bonnier & Layens.
The record derives from TICA
(data supplied on 2012-02-11)
which reports it as a synonym and as an illegitimate name (record 204A2A73-B231-41D1-B9B9-02811ABFFBFE) with original publication details: 412 1879.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:188879-1.
This name was in version 1 of The Plant List, record gcc-1393.