Male
All male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating: an upper pair of cerci (“superior appendages”) and a lower unpaired epiproct (“inferior appendage”).
Male members of the Family Cordulegastridae (Spiketails), including male Twin-spotted Spiketail dragonflies (Cordulegaster maculata), have relatively small cerci (terminal appendages) that can be mistaken for female cerci.
07 MAY 2018 | Fairfax County, VA | Twin-spotted Spiketail (male)
Male dragonfly secondary genitalia, called hamules, are located below abdominal segments two and three (S2 and S3), as shown in the following annotated image. Hamules come in a variety of sizes and shapes, but their function is identical for all species of odonates.
07 MAY 2018 | Fairfax County, VA | Twin-spotted Spiketail (male)
Female
As far as I know I have never seen a female Twin-Spotted Spiketail. (I have seen several individuals that I was unable to photograph.) No problem. Mike Boatwright kindly allowed me to annotate a couple of his photographs.
Photo used with written permission from Mike Boatwright.
These individuals are female, as indicated by their rounded hind wings, terminal appendages, and prominent subgenital plate (ovipositor) at the tip of their abdomen.
Photo used with written permission from Mike Boatwright.
Copyright © 2022 Walter Sanford. All rights reserved.
Tags: cerci, claspers, Cordulegaster maculata, epiproct, Family Cordulegastridae (Spiketails), female, male, ovipositor, subgenital plate, terminal appendages, Twin-spotted Spiketail dragonfly
walter sanford's photoblog 
January 25, 2022 at 3:34 pm |
Thank you, Walter, for more continuing education in Odonata 101!
Of course, I’ll never remember it all, but now I can refer to the expert as needed.
January 25, 2022 at 4:04 pm |
My pleasure, Wally. I hope my guides are helpful in finding and identifying spiketail dragonflies.