Posts Tagged ‘Comet Darner dragonfly’

Comet Darner exuvia: annotated images

October 8, 2021

My last blog post was a “sketch pad” of test shots of an exuvia from a Comet Darner dragonfly (Anax longipes) collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada. All of the shots in that post are unedited JPGs straight from my camera. This post features edited versions of the RAF (raw) files from that photo shoot, including some images with value-added annotations.

Lateral view

I considered annotating the first photo but decided to allow it to stand on its own as the latest addition to my Odonart© Portfolio.

Comet Darner (Anax longipes) | exuvia (lateral)

Ventral view

I used Adobe Photoshop to create a composite image that features the best parts of two photos from the sketch pad.

This specimen is from a male Comet Darner, as indicated by its vestigial primary- and secondary genitalia. The inset photo shows a clear view of the vestigial hamuli (secondary genitalia) that are partially obscured in the background photo.

Comet Darner (Anax longipes) | exuvia (ventral)

Prementum

The last photo shows a closer view of the mentum, a two-segment hinged “jaw” that is used to grab food: the prementum is the segment of the labium closer to the mouth; the postmentum is the segment closer to the base of the head. Only the prementum can be seen in the following photo.

Comet Darner (Anax longipes) | exuvia (prementum)

The preceding annotated image of the prementum includes labels for the moveable hooks (2 of 2) and palpal lobe (1 of 2). Notice that A. longipes palpal lobes are squared off, in contrast with the more rounded shape of the labial palps of Common Green Darner (Anax junius).

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Comet Darner exuvia: photo sketch pad

October 5, 2021

Sometimes I shoot test shots of an odonate exuvia that are used to plan the final shots I have in mind for an identification guide featuring annotated photos.

All of the shots in this post are unedited JPGs straight from my camera, with the exception of the first ventral view (cropped to remove a distracting element from the composition).

Lateral view

I started with a lateral view of an exuvia from a Comet Darner dragonfly (Anax longipes) exuvia collected by Stanley Caveney on 19 July 2021 from a pond at MeadowWoods in West Elgin, Ontario, Canada.

Comet Darner (Anax longipes) | exuvia (lateral)

Ventral view

The next two photos show my frustratingly poor attempts to pose the specimen for shots of the ventral side of the exuvia. Every time I positioned the subject the way I wanted, it rolled over before I could take a shot!

Comet Darner (Anax longipes) | exuvia (ventral)

The two shots combined show the vestigial primary- and secondary genitalia that indicate this specimen is from a male Comet Darner. Yeah, I know it would help to annotate those parts of its anatomy, but that’s the next step. In the meantime, please follow the embedded hyperlink shown above and you might be able to figure out what I’m saying.

Comet Darner (Anax longipes) | exuvia (ventral)

Prementum

The last photo shows a closer view of the prementum. My goal was to get a better look at the labial palps. Again, annotations would help, but if you know what I’m talking about then you can see the palpal lobes are squared off.

Comet Darner (Anax longipes) | exuvia (prementum)

Copyright © 2021 Walter Sanford. All rights reserved.

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.


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