Dave Smallshire's photo.
Amelia's Threadtail male, Gamboa, Chagres River, 30th August 2012.

It looks very similar to Neoneura Esthera but this latter present an abdomen entirely red, and not only the first segments, as here.

Size: 32 mm.
Habitat: river and stream pools in forest, lakes.
Distribution: from southern U.S.A. to Panama.
Panama - Neoneura amelia male 1/1