The Vermonia was invented by Erwald Hochmuth, Klingenthal. I assume, he worked for the VEB Klingenthaler Harmonikawerke (previously VEB Vermona). The patent# DD27979A was granted in 1961.
It is interesting that the slider can be moved to both directions in order to play different scales. Also, the harmonica body is adjustable to change the base key and chords.