Seriously, though, were there any grossly non-humanoid aliens that were UFP members?
, the Ariolo
, the Bzzit Khaht
, the Kasheeta
, and the Zaranites
are Federation Members, and they're awfully alien. Then there are the Antedeans
, the Anticans
, and the Selay
were all in the process of gaining Federation Membership.
But all those examples are clearly humanoid, even described as such in the links you provided. Canonically, it appears the other Federation members just can't stretch enough to accept radically non-humanoid members.
In the novels, the Federation also includes species like the multi-tentacled Sulamid, the jellyfish-like Selenans, the repilian Saurians, the teddy bear-ike S'ti'ach, the tripedal Triexians, the aquatic amphibious Selkies, the Velociraptor-like Pahkwa-thanh, the pillbug-like Nasat, the hideous Medusans, the diminutive Evora, the merpeople-like Aonis, and, of course, the famous rock-eating Horta.
OK, while most of those examples are non-humanoid, what are the Evora doing in there? They're definitely humanoid. Being shorter than average isn't radically alien. Hell, the Evora's diminutiveness probably prompted the Federation to take them on as a protectorate. "Aww, they're so short, it's cute! Let's protect them!"