This is a treble viol or vihuela de arco based on a wall painting in Knights' Hall of Goldegg Castle in the Pongau area (1536).
These paintings are atributed to Hans Bocksberger the older together with other painters. His style contains German elements (A. Dürer) as well as Italian characteristics (Renaissance, Mannerism).
He might have learned with his father and perhaps made some learning years in Italy, anyhow had he exact knowledge of Italian style elements of the time.
His style points both German elements (Albrecht Dürer), and Italian elements (Renaissance and Mannerism).
One of the characteristical features of this instrument is the bridge.
The treble leg goes down (we suppose) on to the back trough a hole on the soundboard.This makes the sound closer to an instrument with a soundpost (sth like a viol or a violin) even though the treble string is slightly unbalanced, gives a weaker sound than the rest (At least in this case, where there is no longitudinal bar or thickening of the soundboard).
It has been built on a board using no mould.
The ribs are inserted in the neck, which goes inside the body and works as a top block.
It has no corner blocks and the joints are reinforced with linen strips. Soundboard is glued on ribs using no linings at all.
The neck in not angled backwards, it is in the same plane as the soundboard. To get the string height, the fingerboard is wedge shaped, giving a thick neck close to the body joint as we can see in the painting.
The soundboard is flat with two small transversal bars aligned with the corners.
The tuning choosen for this instrument has been g c' e' a' d'' taken from the Munich University Library 4º Cod, ms. 718 dated (1523/4) which comes to be the same as Gerle gave in his Musica Teusch (Nuremberg 1532).