This name is a synonym of Betula pubescens var. pumila (L.) Govaerts.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 21666) with original publication details: Consp. Fl. Eur. 672 1881.
This name was in version 1 of The Plant List, record kew-21666, and has not been changed.