walter sanford's photoblog

The Backstory: A Southern Fortnight

For the first two weeks during May 2015, Southern Spreadwing damselflies (Lestes australis) were observed at a vernal pool and nearby drainage ditch in the forest at Huntley Meadows Park. I spotted approximately six males and several females during the fortnight. Their sudden disappearance seemed to coincide with a population explosion of Eastern Pondhawk dragonflies (Erythemis simplicicollis) in mid-May. Eastern Pondhawks, especially females, are voracious predators with a penchant for preying upon damselflies.

The following annotated image illustrates some of the reproductive anatomy of male and female Southern Spreadwing damselflies.

08 MAY 2015 | HMP | Southern Spreadwing (mating pair, in tandem)

The following annotated image illustrates some of the reproductive anatomy of a female Southern Spreadwing: two cerci (sing. cercus), superior appendages that have little or no function; two styli (sing. stylus), structures that serve as sensors in egg positioning; and an ovipositor  (shown above) that is used to insert eggs into vegetation (endophytic oviposition).

07 MAY 2015 | HMP | Southern Spreadwing (adult female)

According to Ed Lam, author and illustrator of Damselflies of the Northeast, “male Southern and Sweetflag cannot be separated in the field.” It is possible to reverse-engineer a positive identification based upon a single key field mark for female specimens of the two species: Southern Spreadwing females have a much smaller ovipositor than Sweetflag Spreadwing females, as illustrated in the following references.

• Odes for Beginners | Damselfly Claspers & Genitalia | Note the differences in the ovipositors between Common (top) and Sweetflag Spreadwings. Editor’s Note: Common Spreadwing has been split into two species: Northern Spreadwing; and Southern Spreadwing.
• Sweetflag Spreadwing (females)

Sidebar: Damselfly Hook-up and Copulation

After a male damselfly grabs a female with his claspers, he transfers sperm from the genital opening under the ninth abdominal segment (S9) to his hamules, shown above, located beneath the second abdominal segment (S2). Next the pair forms the mating wheel, then the male transfers sperm from his hamules to the female through her genital pore under the eighth abdominal segment (S8). The beginning-to-end process is shown in the following still photos and two-part series of videos.

• Two photographs showing male S9-to-S2 sperm transfer: Great Spreadwing damselfly (Archilestes grandis); American Rubyspot damselfly (Hetaerina americana). Source Credit: Photos used with permission from Dennis Paulson, author of Dragonflies and Damselflies of the East.
• Two Worlds of Dragonflies – Damselfly mating behavior and sperm removal. Part 1. (3:21)
• Two Worlds of Dragonflies – Damselfly mating behavior and sperm removal. Part 2. (1:32)

Digital Scans:

• Lestes australis male (Southern Spreadwing) [JPG]
• Lestes australis male #2 (Southern Spreadwing) [JPG]
• Lestes australis female (Southern Spreadwing) [JPG]
• Lestes australis female #2 (Southern Spreadwing) [JPG]

• Related Resources:
  • Another new species of spreadwing damselfly…
  • A Southern Fortnight, Part 1 – Year-long mystery solved!
  • A Southern Fortnight, Part 2 – Damselfly terminal appendages (male)
  • A Southern Fortnight, Part 3 – Southern Spreadwing damselfly (male)
  • A Southern Fortnight, Part 4 – Southern Spreadwing damselfly (female)
  • A Southern Fortnight, Part 5 – Southern Spreadwing damselflies (mating pairs, in tandem)
  • A Southern Fortnight, Part 6 – Damselfly reproductive anatomy
  • A Southern Fortnight, Part 7 – “Arty”

Copyright © 2015 Walter Sanford. All rights reserved.

Tags: adult female, adult male, cerci, Family Lestidae (Spreadwings), hamules, Huntley Meadows Park, Lestes australis, oviposition, ovipositor, Southern Spreadwing damselfly, styli, vernal pool, wildlife photography

This entry was posted on August 19, 2015 at 4:00 am and is filed under Aperture, Canon 580EX Speedlite, damselflies, digital photography, education, natural science, Panasonic DMC-FZ150, Photoshop. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.