Re: Our three great apes . . .
Chimpanzees are of the genus "Pan" which is normally agreed to have two distinct species: Pan paniscus (the Bonobo) and Pan troglodytes (the common Chimpanzee).
Dogs, however are all considered to be a single species, Canis familiaris.
The distinction is due to the amount of differences between the DNA of the types, and also whether it is genetically possible for different types to interbreed - in the case of dogs, apart from sheer physical incompatability any breed of dog can produce viable offspring with any other breed of dog.
This is not believed to be possible between robust and gracile chimps.