jumping ants! (Bulldog ants)
exploding ants (suicide ants)
ants that eat everything (siafu/driver ants)
       on this last mention, there should be be a level with ants eating something dead, like these driver ants:

Driver ants don't eat everything, in fact the diet of most driver ants is very limited (Eciton for example often kills small frogs, reptiles and snakes but does not and cannot eat them).
Yes, there are ants that eat meat (some species of driver ants do and some "normal" ants like the australian meat ans specialize in it) but the majority of ants doesn't really eat animal meat (they specialize more on eating insects and other arthropods).

Also we already have that? There are levels with dead shrimp and even dead fish to eat.

And driver ants and carpenter ants are already planned.