This name is a synonym of Acer pectinatum subsp. laxiflorum (Pax) A.E.Murray.
The record derives from WCSP (in review)
(data supplied on 2012-03-26)
which reports it as a synonym with original publication details: Pflanzenr. IV, 163: 36 1902.
This name was in version 1 of The Plant List, record kew-2615848, and has not been changed.