User blog comment:Logo8th/More Unknown Creatures from the Pottermore Map/@comment-27143814-20171209235629

If I recall rightly there was confusion over whether the Snallygaster, being dragonish, was actually a dragon, with it later being revealed as being more closely related to the Occamy. Over on themonsterblogofmonsters I ended up positing that maybe Occamies were actually closely related to dragons as well, and it was a line of relation and not mimicry of appearance alone, esp. given magical creatures have no trouble interbreeding weirdly (skrewts being born of manticores and fire crabs).

And yeah! Exactly. So I would say Shrake, unless the new film gives us some weird fish. Which it might! We never know. I'll probably be getting the artbook for the new film just as I did the first FB, just in hope of new creatures.