Justin Bieber: New Chica is Selena Gomez 2.0

Justin Bieber's new gal pal has a striking resemblance ... to one Selena Gomez.

The Biebs was chillin' with Puerto Rican model Alexandra Rodriguez on a yacht down in Miami. Hard to tell ... but she might be wearing his swim trunks ... which doesn't do her any justice. Check out the pics below ... Alexandra can wear the hell out of a red bikini.

Justin definitely knows how to ride.