An enraged subway conductor punched a teenager yesterday in an argument over the youth resting his feet on a seat, cops said.

Christopher Thomas, 35, and the 18-year-old, exchanged angry words on a Manhattan-bound R train near the 36th Street station in Queens at 3:50 a.m.

Thomas, who joined the MTA in March 2007, eventually lost his cool and struck the teen, cops said.

He was arrested for misdemeanor assault.

The teen was not seriously injured.

Thomas’ record includes a bust in 1993 for robbery and menacing. He also has five sealed arrests and was collared in April of last year for an alleged assault, cops said. The disposition of the cases was not immediately known.