If there's one thing I know about frogmen, it's that they lust after human women.
So the frogmen come in all kinds of psychedelic colors (probably by clan), and so do the half-naked spear-wielding swamp women.
On a more serious note, LE Mictlan already does frogmen, so another nation of frog people would need an additional hook. Anyone know anything about the cultures of precolombian Brazil?
http://upload.wikimedia.org/wikipedi...e3/Kuarup3.jpg
Those guys certainly have the requisite bright color scheme.