Dennis Paulson's photo (taken at long distance from boat with 500 mm lens), Panama Canal above Gamboa, 23th August 2012.
Members of this genus are either red or have black or blue thorax with red abdomen. They tend to perch low over the water on floating objects and fly rapidly over the surface of ponds and lakes in tropical rainforest habitats. Nothing is known of their breeding, very little about their behavior. This one was on a side channel of Gatun Lake, adjacent to the Panama Canal. The species is widely distributed in northern South America but known only north to the Canal Area in Central America. Dennis Paulson's comments.

P. phoenicura looks like Erythemis peruviana, but his abdomen is all red. Total length of the female: 33 mm.
Planiplax phoenicura male 1/1