Posts Tagged ‘Dromogomphus spinosus’

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.

Dromogomphus spinosus exuvia (ventral view)

February 16, 2021

A dragonfly exuvia was collected by Joe Johnston on 22 May 2019 at Aquia Creek, Stafford County, Virginia USA. This specimen is the cast skin from a Black-shouldered Spinyleg (Dromogomphus spinosus) larva (nymph). D. spinosus is a member of Family Gomphidae (Clubtails).

The specimen is approximately 3.3 cm (~1.3 in) long, measured from head to tail.

15 FEB 2021 | BoG Photo Studio | D. spinosus exuvia (ventral)

Male odonates have two sets of sex organs: primary genitalia located on abdominal segment nine (S9); and secondary genitalia located on abdominal segments two-to-three (S2-3).

This male specimen has too much dirt on S9 to see the primary genitalia; the secondary genitalia are visible on S2-3. I plan to annotate the image in order to highlight select anatomical features.

Related Resources

Tech Tips

The subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. The exposure was increased by 0.3 stop during post-processing in order to attain a pure white background.

A composite image was created from several photos taken using a Fujifilm X-T3 digital camera, Fujifilm MCEX-11 extension tube, Fujinon XF80mm macro lens, and an array of external lights.

One external flash unit was used to create the white background and two others to light the subject. A Sunpack LED 160 was used as a focusing aid.

RAW FILE CONVERTER EX 3.0 was used to convert six (6) RAW (RAF) files to TIFF files. In a departure from my usual workflow, the TIFF files were loaded into Adobe Photoshop CC 2017 in order to create the focus stacked composite image. The composite image was edited using Apple Aperture and sharpened using Photoshop.

Tech Take-aways

Notice there is some color fringing (mostly reds) that is especially noticeable on the front legs and antennae, as well as along the edges of the posterior abdomen. I have been experimenting with a new technique for backlighting the subject. It appears I need to add another layer of diffusion between the light source and the subject.

There is also some “softness” along the edges of the abdomen that could be the result of too few focus points for the shape of the body, which in turn, could have caused artifacts in the composite image.

Copyright © 2021 Walter Sanford. All rights reserved.

Dromogomphus spinosus exuvia

June 28, 2019

A dragonfly exuvia was collected by Joe Johnston on 22 May 2019 at Aquia Creek, Stafford County, Virginia USA. This specimen is the cast skin from a Black-shouldered Spinyleg (Dromogomphus spinosus) larva (nymph). D. spinosus is a member of Family Gomphidae (Clubtails).

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!

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.

The Backstory

Joe Johnston is an avid boater and sport fisherman who kindly agreed to be my “Eyes on the Aquia,” always on the lookout for odonate exuvia to share with me. On 22 May 2019 Joe caught a largemouth bass that swam around one of the wooden pilings of a boat dock that extends far into Aquia Creek. The fishing line was snagged on the piling so Joe moved his boat into position to free the fish. That’s when he noticed the exuvia clinging to a piling on the underside of the dock. Good catches, Joe!

Tech Tips

The following equipment was used to shoot the quick-and-dirty handheld macro photograph featured in this post: Fujifilm X-T1 digital camera; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Actually, back-button focus was used to autofocus the image and adjusted manually as necessary. That’s also a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/9; 1/180s.

Godox XProF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control an off-camera Godox TT685 Thinklite TTL Flash (TT685F) set for radio slave mode. The flash was fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image, plus add annotations.

Sometime in the future (probably the odonate “off-season”) I will create higher quality composite images of this exuvia, shown from all viewpoints including the ventral view. As it turns out, the dorsal view is sufficient to identify this species.

Copyright © 2019 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg (female)

June 26, 2019

A Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted by my good friend Mike Powell during a photowalk along a small forest stream at an undisclosed location in Prince William County, Virginia USA.

This individual is a female, as indicated by her rounded hind wings and terminal appendages.

21 JUN 2019 | PNC. Wm. County, VA | Black-shouldered Spinyleg (female)

Notice the broad, mostly black stripe on the shoulder of her thorax, and large spines on the femur — two field marks from which the common name of this species is derived.

21 JUN 2019 | PNC. Wm. County, VA | Black-shouldered Spinyleg (female)

As this relatively young individual matures, its coloration will change from bright yellow to a dull shade of olive green similar to this mature male spotted at another location in Fairfax County, Virginia USA.

The dragonfly is perched on the broad green leaves of skunk cabbage (Symplocarpus foetidus) in both of the preceding photos.

Tech Tips

The first photo is uncropped, that is, full resolution for the Panasonic Lumix DMC-FZ300 superzoom bridge camera (4,000 x 3,000 pixels). Needless to say, I was very close to this cooperative subject!

The second photo is cropped in order to eliminate some leading lines near the edges of the image.

An external flash unit was used for both photos featured in this post. Sometimes other wildlife photographers ask me why I prefer using flash for insect photography. See for yourself by looking at Mike Powell’s photo of the same subject, taken without flash. Although we were literally standing side-by-side when our photos were taken, the difference is striking. Mike’s photo shows the dim ambient light of the place where we photographed the dragonfly better than my photos; in contrast, I prefer to highlight the details of the subject.

Related Resource: Posts Tagged ‘Black-shouldered Spinyleg dragonfly’

Copyright © 2019 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg (female)

July 24, 2018

A Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted along an unnamed small creek in Fairfax County, Virginia USA. This individual is a female, as indicated by her terminal appendages.

19 JUL 2018 | Fairfax County, VA | Black-shouldered Spinyleg (female)

The tip of the dragonfly’s right hind wing appears to be slightly malformed; her ability to fly didn’t seem to be impaired by the malformation.

Look at the full-size version of the following photo. Notice the fuzzy schmutz on her face and legs. I speculate the dragonfly might have enjoyed either a butterfly or moth for her last meal.

19 JUL 2018 | Fairfax County, VA | Black-shouldered Spinyleg (female)

Copyright © 2018 Walter Sanford. All rights reserved.

Later the same day…

July 2, 2018

Later the same day that I spotted my first-of-year Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) at Prince William Forest Park (PWFP), Prince William County, Virginia USA, I spotted another one during a photowalk at Occoquan Regional Park in Fairfax County, Virginia.

This individual is a male, as indicated by his terminal appendages.

Adult flight period

The adult flight period for Black-shouldered Spinyleg is from 03 June to 12 September (peaks in July to August), according to records for Northern Virginia maintained by Kevin Munroe, former manager at Huntley Meadows Park. My earliest sighting is 21 June; my latest sighting is 08 August.

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, a zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, 08 May to 10 October is the adult flight period for Black-shouldered Spinyleg.

Copyright © 2018 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg dragonfly (male)

June 30, 2018

A Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted during a stream-walk along South Fork Quantico Creek in Prince William Forest Park (PWFP), Prince William County, Virginia USA. This is my first-of-year sighting of this species.

This individual is a male, as indicated by his terminal appendages.

Copyright © 2018 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg (males)

July 11, 2017

Several Black-shouldered Spinyleg dragonflies (Dromogomphus spinosus) were spotted recently in Fairfax County, Virginia USA. All of these individuals are male, as indicated by their terminal appendages and “indented” hind wings.

Male 1

Male 1 and 2 were observed along a mid-size rocky stream. It’s possible the photos show the same male observed at different times, although several Black-shouldered Spinyleg have been seen at this location.

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Male 2

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

It seems like all of the male Black-shouldered Spinyleg at this location are very skittish — they flew away almost every time I waded slowly into the stream for a closer shot!

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Male 3

The last male was spotted perching on a large boulder, overlooking Bull Run.

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

The water was too deep on three sides of the rock to allow me to photograph the dragonfly from multiple angles, so I made the most of the only view that was available.

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Copyright © 2017 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg (female)

July 9, 2017

Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted recently along a rocky stream in Fairfax County, Virginia USA. This individual is a female, as indicated by her terminal appendages and rounded hind wings.

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

Notice the spider in front of the dragonfly. Also notice the female is missing part of her left front leg.

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

I followed the female to several perches — she was a very cooperative model, unlike the males I photographed later the same day!

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

26 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (female)

Copyright © 2017 Walter Sanford. All rights reserved.

Black-shouldered Spinyleg (male)

July 7, 2017

A Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted recently along a rocky stream in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and “indented” hind wings.

The first photograph is the “record shot.” Admittedly not my best work, I shot the photo in order to document the first sighting of Black-shouldered Spinyleg at this location.

21 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

As a wildlife photographer with a focus on insect photography, one of my mantras is: “Get a shot, any shot; refine the shot.” The next few photos show how I was able to refine the first shot by being patient and persistent.

21 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Better…

21 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Best…

21 JUN 2017 | Fairfax County, VA | Black-shouldered Spinyleg (male)

Copyright © 2017 Walter Sanford. All rights reserved.


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