Most would ascribe to missing link as that evidence that is missing or not found between species or large change in a species while ignoring small change that occur frequently. As late as the 1700's and 1800's the Catholic church had yet to recognize some Indians of Mexico as human and they were designated animals. When recognized human was there a significant change or was their denial simply thought because they noticed differences.
I don't know of what you write. The Catholic church, at present is not in the field of species definition. And, in any case, I find it intriguing that the church back then would define a target of its proselytization as such. Someone may wish to define a chihuahua and a great dane as different species, but I believe that they would be wrong in the eyes of most people.