It looks just like a Halo 3 elite to me except with scales. He is also just as hunched as the Halo 3 elite in the picture, so maybe they are just both walking.
I'f I'm not mistaken the only time we have seen decent elite skin is when the Arbiter got the mark of shame. They usually have some kind of suit on underneath the armor, so maybe they have always had scaled we just never see them. Or it is just an artistic change, no big deal.
And you can see teeth on the top left mandible.