I have that same one, climbing up an oak tree in the back yard. All I can tell you is it's a Philodendron, as everyone else has already said. Got mine as a cutting from a friend who didn't know what it is either.
Very pretty, quite robust, really likes to climb - mine is 9ft. up the trunk of the oak now. When you're ready to re-pot it, better get it a taller stake to climb on - you can direct it easily to go round and round so it doesn't go straight up and flop over.
