DLC took so long due to porting.
They literally said so. The PZ community just doesn't seem to remember that
I'm personally either expecting it to be 7 + 5 butterflies, or 8 and 5 butterflies for the anniversary leading us to 200 animals.
So far the "multiple exhibit species for the price of one" has only been the case for butterflies, with other types of animals not getting it (no multiple frogs, no multiple flying foxes, no multiple bats, no multiple lizards, etc. etc.) so the odds for any other species to get that treatment seem to be extremely low.