Besides X. morgani praedicta, are there any species whose existence was predicted before they were discovered?
I'd imagine there would be numerous examples of this. One species I can think of is Monocercomonoides sp., before the discovery of which we didn't know any examples of eukaryotes that had completely lost their mitochondria, or the derived forms of these organelles, such as hydrogenosomes and mitosomes. A prediction wasn't necessarily coined by any particular person like in your example, although there might be some papers somewhere that make such a prediction, I'm sure many people hypothesised that it was probably possible for eukaryotes to completely lose mitochondria if their iron-sulfur cluster biogenesis pathway was replaced by a cytosolic system that could fulfil the same role but we didn't know of any that had.



See paper: http://dx.doi.org/10.1016/j.cub.2016.03.053