Julianne Hough Sucks Face with Ryan Seacrest Knockoff

A poor-man's Ryan Seacrest got a little octopus at Nobu restaurant ... courtesy of Ryan's ex, Julianne Hough.

Our sushi sources tell us ... the 2 were all over each other like white on rice ... even licking each other as they munched on raw fish.

On the Seacrest front ... we're told he's moved on.

After all, there are plenty of fish in the sea.