This name is a synonym of Juncus gerardii subsp. atrofuscus (Rupr.) Printz.
The record derives from IOPI
(data supplied on 2012-03-23)
which reports it as a synonym (record 314647) with original publication details: Bull. Soc. Imp. Naturalistes Moscou 41(4): 172 1868.
This name was in version 1 of The Plant List, record kew-314647, and has not been changed.