Brown Spiketail dragonfly (male claspers)

Brown Spiketail dragonflies (Cordulegaster bilineata) were spotted on two days during May 2018 at Occoquan Regional Park. Both individuals featured in this post are male, as indicated by their terminal appendages and slightly “indented” hind wings.

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”).

11 MAY 2018 | Occoquan Regional Park | Brown Spiketail (male)

Notice the epiproct for Brown Spiketail is a wide “plate” that spans both cerci, as shown in the full-size version of the following annotated image.

07 MAY 2018 | Occoquan Regional Park | Brown Spiketail (male)

Male dragonfly secondary genitalia, called hamules, are located below abdominal segments two and three (S2 and S3), as shown in the preceding annotated image. Hamules come in a variety of sizes and shapes, but their function is identical for all species of odonates. Some species of dragonflies and damselflies — such as Ashy Clubtail versus Lancet Clubtail and Southern Spreadwing versus Sweetflag Spreadwing, to name a few — can be differentiated/identified with certainty only by examining the hamules under magnification.

Copyright © 2018 Walter Sanford. All rights reserved.

Tags: Brown Spiketail dragonfly, cerci, claspers, Cordulegaster bilineata, epiproct, Family Cordulegastridae (Spiketails), hamules, male, Occoquan Regional Park, terminal appendages