So far I have encountered Harpies and Evolvians.
The Harpy scanner at T1 is great! Highly worthy the investment and I was doubly lucky that I found them close to my homeworld.
The evolvians… Hmmm love them but man I hope they are rare as hell in production if they remain as they are! +3000 pop growth the moment my coloniser touched down…! Yea Godz! I feel them may be unbalancing unless hard locked to fairly small worlds - much as the Giants seem locked to large but pretty much barren worlds in A3