This name is a synonym of Alternanthera galapagensis (A.Stewart) J.T.Howell.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 1101677) with original publication details: Proc. Calif. Acad. Sci., ser. 4, 1: 57 1911.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:249979-2.
This name was in version 1 of The Plant List, record tro-1101677, and has not been changed.