Nogales, Santa Cruz County, Arizona
Coordinates: 31.335266, -110.936553
October 1, 2017
Determined by Salvador Vitanza
Confirmed by William Edward who said: “The damselfly in question is a female Argia extranea or plana. Females of the two species are probably not 100% separable by photos. These two are so similar only a microscopic examination of the mesostigmal plates would suffice. However, Dennis Paulson in his field guide to Western Odonata states that the black mark on segment nine is a good field mark He states that in 90% of female plana this mark is lacking. Seeing this mark on segment nine added to bright blue/purple coloration of this individual, my guess is that this indeed is a Argia extranea. The females of A. extranea almost always are colored blue and purple while A. plana females are more often plain brown.. However there are exceptions in both cases.
So, I think this is Argia extranea but without full confidence.”