Rough draft:
Picathartes (either)
Humpback Whale
Narwhal
Superb Bird of Paradise
Wilson's Bird of Paradise
Dibatag
Ribbon Seal
Sumatran Rhino
Saiga
Great White Shark
There is not.
A narwhal is as unlikely to be seen in a zoo as a humpback whale... Anyway is not stated in the thread that they must be captive animals. And then a humpback is relatively easy to see (if you're enough rich to travel to the feeding areas)
There was that aquarium in Star Trek that kept Humpbacks...I think it is supposed to be "want to see in a zoo", so Humpback would be unlikely. However, I have seen three of your animals. Of the others I would most want to see a Narwhal.