JENNIFER LOPEZ KISSES NEW BOYFRIEND WITH WEDDING RING ON

Jennifer Lopez's lips say she's moved on to new BF/dancer Casper Smart -- but at least one of her fingers seems to be holding on to her ex.

While J.Lo snuck a few cougar kisses with Casper between rehearsals in L.A. ... she was still sporting what looks a lot like the 8.2 carat wedding ring she got from Marc Anthony.