Africa has the largest diversity of groups of killies ranging from the annuals of Eastern Africa to the plant spawners of West and Central Africa.  Mixed in with all of these groups are the Lampeyes.

While there are not many Asiatic killies, the Aplocheilus of India is the primary group.  Some consider Orysias,  Pseudomuglids and even Australian Rainbows to be closely related and certain have many similar behaviors.

Caribean & Central American killies are primarily members of the Rivulus group, although there are a few other species.

The Mediterranean killies are mostly related to each other in the Aphanius group. They range from Spain, around the Mediterranean Seas into in and around Turkey.  

North American killies are focused on two major groups with some variation,  They range from salt-water species to land-locked fresh water and pretty much everything between. Some species of killifish can be found in every state. 

Unique breeding habits and a huge variety of species are what make South America different than anywhere else.  Annualism is found throughout the continent in nearly all dry regions and the rainforests yield a wide diversity of plant spawning species.