Aeshna tuberculifera vs. Aeshna umbrosa

A. tuberculifera: palps very truncate, with very sharp hook. A. umbrosa: palps truncate, hook not as sharp.
Note that A. tuberculifera's palps have a sharper meso-posterior corner with well-developed tooth.
A. tuberculifera: ovipositor reaches beyond venter 9. A. umbrosa: ovipositor reaches edge of venter 9.
A. tuberculifera A. umbrosa
A. umbrosa has a more abrupt flare in the prementum with a greater ratio of width to length.
Ventral view: A. umbrosa has striped femora and tibia, though this may be hard to tell in some (dry) specimens.
A. tuberculifera (Left) | A. umbrosa (right)