Hamules

Russet-tipped Clubtail dragonfly (Stylurus plagiatus) was spotted during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR). This individual is a male, as indicated by the large russet-colored club at the end of his abdomen and by his prominent hamules.

hamules: paired structures that project from genital pocket under second segment and hold female abdomen in place during copulation Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 11618-116198). Princeton University Press. Kindle Edition.

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. 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.

(See a full-size version of the original photo, without annotation.)

Like many species of Family Gomphidae (Clubtail dragonflies), the hamules of male Russet-tipped Clubtails are conspicuous — there’s nothing subtle about these guys!

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Meme used with permission from Jacki Morrison (Minnesota Dragonflies).

The preceding meme features an outtake from “War of the Coprophages,” an episode of The X-Files (TV Series). Fox Mulder is an FBI agent who investigates paranormal activity; Dr. Bambi Berenbaum is a fictional scientist named after American entomologist Dr. May Berenbaum. I wasn’t into dragonflies when the episode aired in 1996, so the snippet of risque dialog about cockroaches (quoted in the meme) was lost on me. In retrospect, it’s clear that at least one of the writers/consultants for the episode must be quite familiar with dragonflies!

Copyright © 2016 Walter Sanford. All rights reserved.

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