Lance-tipped Darner (Aeshna constricta) male Power Lines Sherborn MA August 27, 2013
To quote Ed Lam from a Facebook note of his on Gerry Teal's post of August 7, 2014 "Abdominal segment 2 has a diamond-shaped mark on top which better matches Lance-tipped. That mark is usually more linear in Black-tipped. Also [with regards to wing venation] the hindwing anal triangle has three cells. Lance-tipped [and Shadow Darner] has three cells while Black-tipped [Green-striped and Canada Darners] have two."