Coma, eighth overall before the stage but who moved into fourth position following his victory, came in on his KTM motorbike at least 10 minutes clear of his rivals including France's overall leader Cyril Despres, who finished second.
Chile's fifth stage victor Francisco Lopez finished fourth on the stage behind Portuguese rider Helder Rodrigues.
The stage was marred by a serious injury suffered by Italian rider Luca Manta following a fall.
Manta, ninth overall going into the stage, was flown by helicopter to hospital but neither the circumstances of the crash or his state of health were known.