Posts Tagged ‘Twin-spotted Spiketail dragonfly’

Twin-spotted versus Brown Spiketails

February 8, 2022

Four species of genus Cordulegaster are found in the Commonwealth of Virginia: Brown Spiketail (C. bilineata); Tiger Spiketail (C. erronea); Twin-spotted Spiketail (C. maculata); and Arrowhead Spiketail (C. obliqua).

According to the excellent datasets for the Commonwealth of Virginia by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight periods for spiketail dragonflies are as follows.

MAR 16 – JUL 10 = Twin-spotted

MAR 28 – AUG 08 = Brown

MAY 11 – JUL 17 = Arrowhead

MAY 28 – AUG 22 = Tiger

As you can see, there’s a lot of overlap between the flight periods for Twin-spotted Spiketail and Brown Spiketail. Also notice the overlap between the flight periods for Arrowhead Spiketail and Tiger Spiketail.

I think we can agree the distinctive arrowhead-shaped yellow markings on the abdomen of Arrowhead Spiketail (shown below) are unmistakeable for any other species of spiketail, including Tiger Spiketail.

07 JUL 2014 | Fairfax County, VA | Arrowhead Spiketail (male)

In the opinion of the author it’s more likely a dark-colored Brown Spiketail, such as the one shown below, might be misidentified as a Twin-spotted Spiketail.

02 MAY 2019 | Fairfax County, VA | Brown Spiketail (male)

Differentiating Twin-spotted versus Brown

Twin-spotted and Brown Spiketail dragonflies can be differentiated by looking closely at the yellow markings on abdominal segments one through three (S1-S3).

07 MAY 2018 | Fairfax County, VA | Twin-spotted Spiketail (male)

The pattern of yellow markings on S1-S3 is simpler for Twin-spotted than Brown, as you can see by looking at the full-size versions of these two photos, shown above and below.

11 MAY 2018 | Fairfax County, VA | Brown Spiketail (male)

Female Twin-spotted versus Brown

Female Twin-spotted Spiketails, such as the one shown below, have a much longer subgenital plate (ovipositor) than female Brown Spiketails.

Photo used with written permission from Mike Boatwright.

The subgenital plate for the following female Brown Spiketail is barely visible.

09 MAY 2013 | Fairfax County, VA | Brown Spiketail (female)

It isn’t a lot easier to see the subgenital plate in a close-up view of the same individual shown above.

09 MAY 2013 | Fairfax County, VA | Brown Spiketail (female)

Coach’s Corner

Thanks to Mike Boatwright, founder and administrator of the Virginia Odonata Facebook group, for coaching me up on how to differentiate Twin-spotted Spiketail from Brown Spiketail, including both males and females.

Look for yellow markings on the side of abdominal segments one through three (S1-S3): green arrows show the lack of yellow markings on S1-S3 for Twin-spotted; red arrows show yellow markings on the sides of S1-S3 for Brown.

Set 1

Twin-spotted Spiketail | male (dorsal view)

Photo used with written permission from Mike Boatwright.

Brown Spiketail | male (dorsal view)

Photo used with written permission from Mike Boatwright.

Set 2

Twin-spotted Spiketail | male (dorso-lateral view)

Photo used with written permission from Mike Boatwright.

Brown Spiketail | male (dorso-lateral view)

Photo used with written permission from Mike Boatwright.

What are the take-aways?

Remember the odonate hunter’s credo: Shoot first (photographs, that is); ask questions later. (Repeat it like a mantra.) Get a shot, any shot; refine the shot gradually.

Please don’t waste precious time in the field! You can study the photos when you return home in order to identify the subject(s) you shot as either Twin-spotted Spiketail or Brown Spiketail.

Copyright © 2022 Walter Sanford. All rights reserved.

Twin-spotted Spiketail (terminal appendages)

January 25, 2022

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.

New Life List additions in 2018 (odonates)

December 28, 2018

The anticipation of the hunt and the thrill of discovery — the adrenalin rush from finding the target species is ever more elusive as one gains experience and expertise. Accordingly, the number of additions to my Life List is fewer year after year.

Editor’s Note: List items are presented in chronological order, based upon the date of the spotting.

Twin-spotted Spiketail

A Twin-spotted Spiketail dragonfly (Cordulegaster maculata) was spotted at an undisclosed location in Fairfax County, Virginia USA. This individual is a male.

07 MAY 2018 | Fairfax County, VA | Twin-spotted Spiketail (male)

Brown Spiketail (male)

A Brown Spiketail dragonfly (Cordulegaster bilineata) was spotted at an undisclosed location in Fairfax County, Virginia USA. I saw a female Brown Spiketail on 09 May 2013. This individual is one of several males that I spotted on 07 and 11 May 2018.

11 MAY 2018 | Fairfax County, VA | Brown Spiketail (male)

Gray Petaltail

Gray Petaltail dragonfly (Tachopteryx thoreyi) was spotted at a forest seep. This individual is a male with a malformed abdomen that I nicknamed “Bender.”

06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

Sable Clubtail

Sable Clubtail dragonfly (Stenogomphurus rogersi) was spotted perched near a small stream located in Fairfax County, Virginia USA. This individual is a male.

08 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Citrine Forktail damselfly (male)

Citrine Forktail damselfly (Ischnura hastata) was spotted during a stream-walk along South Fork Quantico Creek in Prince William Forest Park (PWFP), Prince William County, Virginia USA. This individual is a male.


Next post: Recognition in 2018.

Copyright © 2018 Walter Sanford. All rights reserved.

Twin-spotted Spiketail (male claspers)

May 17, 2018

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.

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.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

Twin-spotted Spiketail dragonfly (male)

May 9, 2018

A Twin-spotted Spiketail dragonfly (Cordulegaster maculata) was spotted at Occoquan Regional Park in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and “indented” hind wings.

Those who know me well are familiar with one of many “Walterisms”: “I haven’t ‘seen’ something until I have photographed it.” My rationale is two-fold: 1) A photograph verifies a sighting. 2) The detail visible in a good photograph exceeds the acuity of the human eye.

Although I’m fairly certain I’ve seen a Twin-spotted Spiketail at another location, this is the first time I was fortunate to photograph the species. Twin-spotted Spiketail is relatively uncommon in Northern Virginia.

The last two photos show what might be the same male shown in the first two photos, but it might be another male. As Mike Powell and I were photographing the first male, another dragonfly swooped in and there was either a brief aerial ballet or battle, depending upon whether the second dragonfly was a female or male. I visually tracked the first dragonfly to a new perch about 10 feet away.

When I started to move toward the new perch, Mike shouted “Don’t move, don’t move!” Mike had spotted another Twin-spotted Spiketail that landed close to the place where I spotted the first one.

We didn’t have much time to shoot photos. This Twin-spotted Spiketail and another one hooked up and they flew in wheel toward the nearby treetops. The mating process for Twin-spotted Spiketails lasts about an hour, a fact that may explain why we never saw another Twin-spotted during our photowalk.

Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.

  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | male | top view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | male | side view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | female | top view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | female | side view

Copyright © 2018 Walter Sanford. All rights reserved.


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