This name is a synonym of Aristida adscensionis L..
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym and as an invalid name (record 469190) with original publication details: Novosti Sist. Vyssh. Rast. 8: 74 1971.
This name record (from WCSP) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Arthratherum adscensionis in version 1 of The Plant List.