This name is a synonym of Rhynchospora gigantea Link.
The record derives from WCSP which reports it as a synonym (record 239514) with original publication details: Publ. Field Mus. Nat. Hist., Bot. Ser. 11: 6 1931.
Full publication details for this name can be found in IPNI: urn:lsid:ipni.org:names:79568-2.