This name is a synonym of Cypripedium himalaicum Rolfe.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50052178) with original publication details: Orch. 1: 26 1897.
This name record (from Tropicos) 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 Cypripedium macranthon in version 1 of The Plant List.