Diocletian, AE 22mm As. 5.41g. Rome mint. 285-286 AD.

IMP DIOCLETIANVS AVG, laureate, draped, cuirassed bust 
right, seen from the back.
IOVI CONSERVAT AVG, Jupiter, chlamys hanging behind from
 left shoulder, standing left, holding thunderbolt and sceptre. 
Not in RIC, Cohen, Gerin, Ackerman,  etc. 
RIC V-2 199 Rome var (rev legend, bust type)

Courtesy of Numismatik Lanz, Auktion 100, Leo Benz III Collection, lot 457.