I have in the past, been one to feel outward appearance was an important genus indicator.
But the more I learn about radiation of species flocks, during different geological epochs, the more I question my views.
Because the effects of convergent evolution, species in Africa can have an outward appearance very similar to South or Central America, compare the African Heterochromis multidens with many Centrals, it may be a primitive link between the 2, with a primitive ancestor present at the time of continental drift.
Or divergent evolution where because of food supplies, or the lack thereof a
single species may become 2, and in the end appear very different.
This may be occurring in Cuatro Cienegas where 3 species may be evolving from Herichthys minckleyi because of 3 different food supplies available.
And in small recently created African lakes such as Barombi mbo, in a short period of time (geologically speaking), those cichlids that would be thought of as simply Tilapia, have now become Stomatepia, Pundu, Konia, and more geni due to food specialization.
Not long ago Nandopsis not only included the Caribbean species, but those that have become Parachromis. Today there seems to be enough evidence to isolate the island species.
Compare Konia eisentraudti with Stomatepia pindu, both may be from the same Tilapine ancestor
