Please Help With ID

ID Wanted

I've posted photos of this duck and his/her mate about a year ago. I'm still trying to find out what kind of duck this is. With all the nature photographers out there, I can't believe no one knows what it is called. I've only found one other photo of ducks that look like this through Google and I think it was the same pair. Whoever posted it didn't include the name, so it was no help.

They are so pretty. They hang on a little pond in Gulfport, FL along with some Mottled Ducks, White Ibis, a pure white duck, a few Mallards and a couple of Moorhens. There is only 1 pair of them. They are much larger and longer-backed than Mallards as you can see in this photo.

Your help is greatly appreciated. Thanks for looking.