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 224757) with original publication details: J. Jap. Bot. 30: 312 1955.
This name was in version 1 of The Plant List, record kew-224757.