This name is a synonym of Cycas micronesica K.D.Hill.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 383428) with original publication details: J. Jap. Bot. 14: 587 1938.
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 Cycas rumphii in version 1 of The Plant List.