This name is a synonym of Bryum muehlenbeckii subsp. appressum (Kindb.) Podp..
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 35116140) with original publication details: Hedwigia 35: 66 1896.
This name was in version 1 of The Plant List, record tro-35116140, and has not been changed.