This name is a synonym of Crataegus ambigua C.A.Mey. ex A.K.Becker.
The record derives from RJP
(data supplied on 2011-10-18)
which reports it as a synonym (record 1646) with original publication details: ; 1952 57, f.1 1952.
This name record (from RJP) 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 Crataegus helenae in version 1 of The Plant List.