Posts Tagged ‘exuvia’

Anax junius versus Anax longipes

September 10, 2021

The following photograph shows the relative size of odonate exuviae from two species in the Genus Anax: junius; and longipes. Both specimens are from the Family Aeshnidae (Darners).

Relative size of exuviae from Anax junius versus Anax longipes.

The Common Green Darner dragonfly (Anax junius) exuvia was collected on 17 June 2021 from a small pond at an undisclosed location in Prince William County, Virginia USA.

The Comet Darner dragonfly (Anax longipes) exuvia was collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada.

Taxonomy

There are five species of dragonflies in the Genus Anax for the United States and Canada: Amazon Darner (Anax amazili); Common Green Darner (Anax junius); Comet Darner (Anax longipes); Giant Darner (Anax walsinghami); and Blue-spotted Comet (Anax concolor).

Common Green Darner and Comet Darner are the only species from the Genus Anax found where I live in Northern Virginia USA.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Comet Darner dragonfly (exuvia)

August 27, 2021

An odonate exuvia from a Comet Darner dragonfly (Anax longipes) was collected by Stanley Caveney on 19 July 2021 at MeadowWoods in West Elgin, Ontario, Canada.

This specimen is from Family Aeshnidae (Darners), as indicated by the following field marks: the exuvia has a flat labium that doesn’t cover the face (not mask-like); the antennae are thin and thread-like (not club-like, as in Gomphidae larvae/exuviae); and the eyes are large relative to the size of the head.

19 JUL 2021 | Ontario, Canada | Comet Darner exuvia (lateral view)

Lateral spines along abdominal segments seven, eight, and nine (S7-9) indicate the genus is Anax; the length of the exuvia indicates longipes (~6 cm, measured as is).

The Backstory

Stanley Caveney is shown in the first of several photos taken by Hugh Casbourn. Stan contacted me for confirmation of his tentative identification of several Comet Darner exuviae that he collected during July 2021. Stan kindly gave one of the exuviae to me.

Photo used with written permission from Hugh Casbourn.

I asked Stan whether he had taken photographs of the Comet Darner exuviae in situ. Stan hadn’t, so he and Hugh revisited a local pond where they searched for and found two more exuviae.

How many exuviae do you see in the next photo? Look closely — both cast skins are shown in the same image.

Photo used with written permission from Hugh Casbourn.

An exuvia from a female Comet Darner appears in the foreground of the preceding photograph…

Photo used with written permission from Hugh Casbourn.

and a male Comet Darner appears in the background.

Photo used with written permission from Hugh Casbourn.

I asked Stan for advice regarding where to look for Comet Darner exuviae.

The six exuviae found to date were mainly at the inner edge of the cattail beds, facing the open water of the pond and where the individual cattail plants were spaced out. Source Credit: Personal communication from Stanley Caveney.

Related Resource: Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz. Refer to pp. 21-22.

Editor’s Note: Sincere thanks to Derek Caveney, Stan’s son, for shipping the exuvia to me. The specimen was packed so carefully that it arrived in excellent condition, as you can see in the first photo in this blog post. I’m looking forward to shooting a complete photo set of the exuvia.

Copyright © 2021 Walter Sanford. All rights reserved.

Post update: Stylurus sp. exuvia

July 27, 2021

Three years ago I had the honor and pleasure of helping Michael Boatwright, my good friend and odonate hunting buddy, identify an interesting exuvia that he collected on 13 July 2018 at an undisclosed location in Amherst County, Virginia USA.

After working through several dichotomous keys for the identification of odonate larvae/exuviae, Mike and I determined the specimen is most likely from Zebra Clubtail (Stylurus scudderi). Zebra Clubtail is extremely rare in the state of Virginia.

The following annotated image shows a dorsal view of the exuvia.

13 JUL 2018 | Amherst County, VA USA | Stylurus scudderi (exuvia)

The best way to confirm our tentative identification of the exuvia is to find adult Zebra Clubtail at the same location. Easier said than done! During the next few years, Mike found more exuviae but no adults.

On 22 July 2021, years of searching the site finally came to fruition when Mike discovered a teneral female Zebra Clubtail, shown below.

Photo used with written permission from Mike Boatwright.

Look closely at the full-size version of the preceding photo. Notice the teneral dragonfly is perched on the exuvia from which it emerged. Mike collected the exuvia after the dragonfly flew high into the tree canopy, so now we have the type specimen for verification of other exuviae.

Persistence pays

Sincere congratulations, Mike! You never gave up when it would have been the easier thing to do.

Related Resources

  • Stylurus sp. exuvia – a blog post by Walter Sanford providing a detailed account of the process used to determine the identity of the specimen collected by Mike on 13 July 2018.
  • Mike’s post in the Virginia Odonata Facebook group announcing his discovery on 22 July 2021. Mike is the founder and administrator of Virginia Odonata.

Copyright © 2021 Walter Sanford. All rights reserved.

Post update: What is it?

July 6, 2021

I spotted an odonate exuvia along the shoreline of a small pond at an undisclosed location in Prince William County, Virginia USA that was collected by Mike Powell, my good friend and photowalking buddy.

This specimen is from the Family Aeshnidae (Darners), as indicated by the following field marks: the exuvia has a flat labium that doesn’t cover the face (not mask-like); the antennae are thin and thread-like (not club-like, as in Gomphidae larvae/exuviae); and the eyes are large relative to the size of the head.

17 JUN 2021 | PNC. Wm. County | Anax junius exuvia

Lateral spines along abdominal segments seven, eight, and nine (S7-9) indicate the genus is Anax; the length of the exuvia indicates junius (greater than ~4 cm, measured as is).

Common Green Darner dragonfly (Anax junius) is one of the more common species of Aeshnidae found in Northern Virginia.

Related Resource: What is it?

Copyright © 2021 Walter Sanford. All rights reserved.

What is it?

June 22, 2021

Ladies and gentlemen, children of all ages. It’s time for another exciting episode of “What is it?”

The Backstory

I spotted an odonate exuvia along the shoreline of a small pond at an undisclosed location in Prince William County, Virginia USA.

17 JUN 2021 | PNC. Wm. County | odonate exuvia

Mike Powell, my good friend and photowalking buddy, volunteered to collect the exuvia. I accepted his kind offer since I prefer dry shoes rather than wet ones. The following photo shows me holding the specimen immediately after Mike made the hand-off.

Photo used with written permission from Michael Powell.

Can you identify the odonate exuvia to the family level?

It should be easier to determine what it is by referring to A Beginners’ Guide to Identifying the Exuviae of Wisconsin Odonata to Family, by Freda Van den Broek and Walter Sanford. Although the guide is focused primarily on odonate exuviae found in Wisconsin, it should be useful for any location in the United States of America including Virginia.

I’m still working to identify the specimen to the genus and species level. Your mission, should you decide to accept it, is to identify the family of odonates to which this exuvia belongs.

If you think you know what it is, then please leave a comment. The answer will be revealed in a post update.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Uhler’s Sundragon dragonfly exuvia

June 1, 2021

Michael Powell spotted a small odonate exuvia clinging to the base of one of two concrete abutments for a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

I collected the exuvia in order to examine it more closely in my home laboratory/photography studio. Michael photographed the specimen in my hand immediately after I removed it from the abutment, as shown in the following photo.

Photo used with written permission from Michael Powell.

The first photo shows a face-head view of the exuvia.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

The next two photos, showing a dorsal-lateral view of the specimen, confirm the exuvia is from a Uhler’s Sundragon dragonfly (Helocordulia uhleri).

Notice the dorsal hooks on abdominal segments seven through nine (S7-9). This distinctive character confirms the identity of the specimen as H. uhleri.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

Another photo taken from the same view point, exposed and edited for more contrast, shows the three dorsal hooks a little more clearly than the preceding photo.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (exuvia)

Knowing when good is good enough

A dear friend sent an article to me years ago entitled “Knowing when good is good enough.” I think she was trying to tell me something.

I tend to be a perfectionist. For example, I’m a man on a mission to take the best possible macro photographs of odonate larvae and exuviae given the limitations of my photography gear and small home studio.

Sometimes perfection is a road block that prevents me from shooting and posting photos that are more than serviceable for my purposes, in this case, informal instruction.

I did a quick Google search for the article from my friend. No luck, but I found one that’s close enough — you might even say one that’s good enough — for a little self-help.

None of the photographs in this blog post are perfect — not even close! But I published them anyway. Baby steps, Bob.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Stream Cruiser dragonfly (female)

May 18, 2021

A Stream Cruiser dragonfly (Didymops transversa) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This individual is a female, as indicated by her thick abdomen and terminal appendages.

13 MAY 2021 | Prince William County, VA | Stream Cruiser (female)

The female was perched in a large field near the same location where Mike Powell found a Stream Cruiser exuvia on 13 April 2021.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Exuvia from Family Macromiidae (Cruisers)

May 14, 2021

Michael Powell spotted a large odonate exuvia clinging to the concrete abutment of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This cast skin is definitely from a member of Family Macromiidae (Cruisers), as indicated by its long legs and the shape of its body.

13 APR 2021 | Prince William County, VA | Stream Cruiser (exuvia)

Mike’s macro photo of the same subject (shown below) turned out better than mine, taken with a superzoom bridge camera. Look closely at the full-size version of Mike’s photo. Nothing says Family Macromiidae (Cruisers) like the “horn” on the front of the face/head of the exuvia!

Photo used with written permission from Michael Powell.

The following excerpt from Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, shows the couplet that I think indicates this specimen is from a Stream Cruiser dragonfly (Didymops transversa).

The adult flight periods for the three species of cruisers found in Northern Virginia provide circumstantial evidence in support of my tentative identification. Source Credit: “Dragonflies of Northern Virginia” Web site by Kevin Munroe.

What’s next?

The specimen was collected in order to shoot a complete set of macro photographs of the exuvia in my home “studio.”

Copyright © 2021 Walter Sanford. All rights reserved.

Post update: Tachopteryx thoreyi exuvia

March 26, 2021

I just updated an older blog post in order to correct a label for an anatomical structure that was mislabeled, plus I added some new information.

The updated annotated image is shown below.

No. 2 | Gray Petaltail (Tachopteryx thoreyi) | exuvia (dorsal)

While I was editing the photo, I noticed something I hadn’t seen before — a large dorsal hook of abdominal segment nine (S9) that overhangs segment 10 (S10). This time I’m fairly sure the structure is correctly called a dorsal hook.

Related Resource: Tachopteryx thoreyi exuvia, an updated version of a blog post by Walter Sanford.

Copyright © 2021 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia (dorsal view)

February 19, 2021

Gomphidae (Clubtails) is the second largest family of dragonflies, behind Libellulidae (Skimmers). Many types of clubtail larvae (nymphs)/exuviae look similar, adding to the challenge of identifying some specimens to the genus and species level.

This specimen has a flat labium that doesn’t cover the face (not mask-like), indicating it’s either Aeshnidae (Darners) or Gomphidae; the shape of the body suggets Gomphidae. Several more field marks can be used to identify this specimen as a Black-shouldered Spinyleg (Dromogomphus spinosus) exuvia.

16 FEB 2021 | BoG Photo Studio | D. spinosus exuvia (dorsal)

The specimen is approximately 3.3 cm (~1.3 in) long, measured from head to tail. Notice the mid-dorsal hooks/spines located along the abdomen of the body.

At first I thought the exuvia might be a species from the genus Stylurus, based upon the mid-dorsal spine on abdominal segment nine (S9). After careful examination of two excellent photo-illustrated PowerPoint presentations by Kevin Hemeon at NymphFest 2016 (see Related Resources, below), I noticed none of the species in the genus Stylurus have dorsal hooks. That’s when I realized the specimen must be D. spinosus. Eureka! Source Credit: Dromogomphus spinosus exuvia – a blog post published on 28 June 2019 by Walter Sanford.

Related Resources

The following PowerPoint presentations by Kevin Hemeon are available in the “Files” section of the Northeast Odonata Facebook group. Direct links to the documents are provided below.

Odonate Exuviae – a hyperlinked list of identification guides to many species of odonate exuviae from seven families of dragonflies and three families of damselflies.

Tech Tips

The photograph featured in this blog post is a “one-off,” that is, a single photo rather than a focus-stacked composite image. The camera lens was set for f/16; the camera body was set for ISO 160 and a shutter speed of 1/250 s.

The photo was taken using a Fujifilm X-T3 digital camera, Fujifilm MCEX-11 extension tube, Fujinon XF80mm macro lens (120mm, 35mm equivalent), and an array of external lights.

Two external flash units were used to create the white background by cross lighting the front of a piece of white plastic; another flash was used to light the subject. A Sunpack LED 160 was used as a focusing aid.

RAW FILE CONVERTER EX 3.0 was used to convert one RAW (RAF) file to a TIFF file. The TIFF file was edited using Apple Aperture and sharpened using Photoshop.

Copyright © 2021 Walter Sanford. All rights reserved.


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