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 (record 19488) with original publication details: Kew Bull. 56: 29 2001.
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 Aristida mauritiana in version 1 of The Plant List.