DM? Sorry, too old to immediately comprehend what that means.
Briefly, whistling ducks are morphologically very conservative yet genetically and behaviorally very divergent. There are also questions of ILS or other confounding factors in the phylogeny of the greater part of the genus. As far as phylogeography, which has never been looked at, there are a couple of species with unusually broad distribution — over South America, Africa, and, in one case, India too, crossing two (count 'em) two oceans — but zero described subspecific variation. I have a PowerPoint presentation if you’re interested further.
Plenty of other interesting problems in bird phylogeny at all levels, if you’re into in that sort of thing.