This name is a synonym of Carex atrata subsp. aterrima (Hoppe) Hartm..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 224702) with original publication details: Bull. Murith. Soc. Valais. Sci. Nat. 19-20: 80 1890.
This name was in version 1 of The Plant List, record kew-224702.