I'd especially love something like this for exhibit species where you would get, say, five species of a similar group. That way, you could variety among the exhibit species - I think this is especially important as among smaller animals like amphibians, reptiles and especially invertebrates there is less standardisation among zoo collections. It would also deal with the problem that has happened in past DLC where a large and normally diverse group has been represented by just a single species - the stick insects in the Southeast Asia Animal Pack particularly comes to mind here.
Here are a couple of examples I can think of:
Poison frog micro pack
Anthony's poison frog - A Near Threatened species which is red with cream stripes
Dyeing poison frog - A highly variable species that is common in captivity
Green-and-black poison frog - A mostly green species which is extremely common in zoos
Maranon poison frog - An Endangered species which is a rich brown with white spots
Yellow-banded poison frog - A yellow and black species which is extremely common in zoos
With that, you would have five new species that all have some degree of common captive presence to go alongside the two current species (one of which is incredibly rare in zoos).
Stag beetle micro pack
Fighting giant stag beetle
Hexarthrius parryi - A large dark species with yellow spots from the jungles of mainland Southeast Asia
Giant stag beetle
Lucanus elaphus - A large red species from the woodlands of eastern North America
Gladiator stag beetle
Homoderus gladiator - An orange-yellow species with dark spots from the rainforests of Africa
Rainbow stag beetle
Phalacrognathus muelleri - A brightly-coloured species with toothless jaws from the jungles of New Guinea and Queensland
Sumatran giant stag beetle
Cyclommatus elaphus - A large species with an iridescent green base and some orange and purple highlights, from insular Southeast Asia
With this pack, there would be a greater range of biomes and continents represented - more so than the poison frog micro pack, which by its nature is centred entirely on Central and South America.