Posts Tagged ‘epiproct’

Yellow-sided Skimmer (terminal appendages)

August 24, 2021

Female and male Yellow-sided Skimmer dragonflies (Libellula flavida) were spotted at a small pond at an undisclosed location in Prince William County, Virginia USA.

Female

The first individual is a female, as indicated by her mostly yellow coloration and terminal appendages.

17 JUN 2021 | PNC. Wm. County | Yellow-sided Skimmer (female)

Female dragonflies have a pair of cerci (superior appendages) that have little or no function.

Mature male

The last individual is a mature male, as indicated by his light-blue pruinescence and terminal appendages.

17 JUN 2021 | PNC. Wm. County | Yellow-sided Skimmer (male)

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”).

Immature male Yellow-sided Skimmers look similar to females of the same species. Terminal appendages can be used to differentiate the sex of immature males and mature females.

Related Resource: Yellow-sided Skimmer (male and female) – a blog post by Walter Sanford.

Copyright © 2021 Walter Sanford. All rights reserved.

Anatomy of a male Tiger Spiketail

August 10, 2021

The following annotated image shows a Tiger Spiketail dragonfly (Cordulegaster erronea). This individual is a male, as indicated by his hamules, “indented” hind wings, and terminal appendages.

Hamules

Hamules? What are hamules?

hamules: paired structures that project from genital pocket under second segment and hold female abdomen in place during copulation Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 11618-116198). Princeton University Press. Kindle Edition.

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. Some species of dragonflies and damselflies — such as Ashy Clubtail versus Lancet Clubtail and Southern Spreadwing versus Sweetflag Spreadwing, to name a few — can be differentiated/identified with certainty only by examining the hamules under magnification.

Photo used with written permission from Michael Powell.

(See a full-size version of the original photo, without annotation.)

Indented hind wings

Male members of many families of dragonflies have “indented” hind wings near the body, with some notable exceptions.

Hind wing venation and shape can identify the sex of most dragonflies. Petaltails, darners (except Anax), clubtails, spiketails, cruisers, and some emeralds. Wing shape isn’t helpful to sex baskettails since they are largely the same. They are different in Cordulia, Dorocordulia, Somatochlora and to a lesser degree, Neurocordulia. Source Credit: Ed Lam, author and illustrator of Damselflies of the Northeast.

Terminal appendages

Identifying female versus male dragonflies and damselflies can be challenging but it’s a little easier when you know how to differentiate their terminal appendages.

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 dragonfly terminal appendages don’t look exactly the same for all species of dragonflies, but their function is identical.

Generally speaking, spiketail dragonflies have relatively small terminal appendages. That said, they must get the job done!

Related Resource: Tiger Spiketail dragonfly (male) – a blog post by Walter Sanford.

Copyright © 2021 Walter Sanford. All rights reserved.

 

Unicorn Clubtail dragonfly (male)

June 29, 2021

A Unicorn Clubtail dragonfly (Arigomphus villosipes) was photographed near the shoreline of a small pond at an undisclosed location in Fairfax County, Virginia USA.

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

For those of you keeping score at home, notice male Unicorn terminal appendages have four points/prongs. Does that mean A. villosipes is an exception to the rule of three terminal appendages for male dragonflies? In a word, no.

05 JUN 2021 | Fairfax County, VA | Unicorn Clubtail (male)

The preceding photo shows a clear view of the male’s terminal appendages. Zoom-in on the full-size version of the photo and you should notice that the epiproct for Unicorn Clubtail is essentially a wide plate with two points/prongs.

Related Resource: Odonate Terminal Appendages – a permanent reference page in my blog featuring identification guides for most of the common species of odonates found in Virginia, and even some of the uncommon to rare species.

Copyright © 2021 Walter Sanford. All rights reserved.

 

Selys’s Sundragon dragonfly (male)

April 16, 2021

I discovered a Selys’ Sundragon dragonfly (Helocordulia selysii) during a recent photowalk with Michael Powell at an undisclosed location in Prince William County, Virginia USA. Selys’s Sundragon is a new species for my Life List of odonates and for Prince William County, VA. [Odonata Species (p. 1 of 2) — current as of 14 April 2021 — shows part of the species list for Prince William County before Selys’s was added.]

This individual is a male with a malformed abdomen. Notice his abdomen is twisted so that the terminal appendages aren’t in their usual alignment. The cerci should be on top and the epiproct should be on the bottom; they aren’t where they should be.

13 APR 2021 | Prince William County, VA | Selys’s Sundragon (male)

All male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating. Male dragonfly terminal appendages don’t look exactly the same for all species of dragonflies, but their function is identical. The misalignment of this Selys’s terminal appendages might be a problem when attempting to form the “wheel position” with females.

The Backstory

Mike Powell and I were men on a mission to photograph Uhler’s Sundragon dragonflies (Helocordulia uhleri). The sky was completely overcast when we arrived at our destination. According to the weather forecast, the sky was supposed to clear around 1:00 pm, and sure enough it did. Soon afterward, we spotted our first Uhler’s of the day and spent some time photographing several individuals.

All of the Uhler’s we saw were female. At some point I said to Mike (paraphrasing) “I need to photograph at least one male before we leave!” I walked a little farther downstream from a place where Mike was shooting macro photos of a very cooperative female Uhler’s. That’s when I spotted the male shown in the preceding photo.

My first impression was the dragonfly seemed to be noticeably smaller than the female Uhler’s we had been photographing. Turns out I was right! According to Dragonflies and Damselflies of the East by Dennis Paulson, Uhler’s are 41-46 mm in total length (4.1-4.6 cm) and Selys’s are 38-41 mm in total length (3.8-4.1 cm). For those of you keeping score at home, that’s only ~1.5″ long — small for many if not most dragonflies!

Related Resource: Selys’s Sundragon dragonfly – a blog post by Michael Powell, my good friend and photowalking buddy.

Copyright © 2021 Walter Sanford. All rights reserved.

MYN – Eastern Amberwing exuvia (anal pyramid)

March 9, 2020

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.

65mm (3x magnification) | ISO 100 | f/8 | 1/200 s | 0 ev

Look closely at the full-size version of the preceding photo, showing a close-up of the anal pyramid at 3x magnification. Notice the cerci are approximately half as long as the epiproct and slightly less than half the length of the paraprocts. It’s a close call, but the latter field mark indicates Family Libellulidae (Skimmers).

A step-by-step identification guide (to the species level) will be published in a follow-up post. Stay tuned!

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

Building a case for Slaty Skimmer

October 23, 2019

With each new photo set of this unknown species of odonate exuvia, a case is building slowly for Slaty Skimmer (Libellula incesta).

Occoquan Regional Park | unknown species | exuvia (lateral)

A piece of white schmutz was removed from the tip of the abdomen, enabling a clearer view of abdominal segment nine (S9). Look closely at the two photos featured in this post. Notice there are stubby mid-dorsal hooks (not cultriform) on abdominal segments four through eight (S4-S8).

Occoquan Regional Park | unknown species | exuvia (dorsal)

The last photo shows a closer view of the anal pyramid. Notice the lateral caudal appendages (cerci) are less than half as long as the inferior appendages (paraprocts).

Soltesz, p. 43 – Key to the Species of the Genus Libellula

Field marks that match this specimen are highlighted in boldface green text.

1b. Dorsal hooks regularly present on segments 4 to 8. [2]
2b. Palpal setae 5 (sometimes 6 in cyanea). [5]
5a. Epiproct distinctly decurved at tip. [6]
6b. Length of last instar about 26mm; cerci less than half as long as paraprocts. [incesta]

Punch List

I need to look at the inside of the labium (face mask) in order to count palpal setae. The epiproct must be cleaned to see whether it is decurved. This exuvia was deformed as a result of emergence, so it’s impossible to make an accurate measurement of the length of the specimen. That said, the exuvia is more than 22.0 mm (0.9 in) long. (22 mm is the length of the last instar for L. cyanea.)

And of course, I need to annotate all of the images in this series of blog posts in order to illustrate the unfamiliar vocabulary that is used in virtually all dichotomous identification keys.

Related Resources

Tech Tips

The following equipment was used to shoot the quick-and-dirty macro photographs featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-16 extension tube; 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. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/16; 1/180s.

Godox X2TF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control two off-camera external flash units set for radio slave mode: Godox TT685F Thinklite TTL Flash (manual mode); and Godox TT685o/p Thinklite Flash for Olympus/Panasonic Cameras (manual mode). Both flash units were fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image.

Copyright © 2019 Walter Sanford. All rights reserved.

Brown Spiketail dragonflies

May 6, 2019

Several Brown Spiketail dragonflies (Cordulegaster bilineata) were spotted during a photowalk with my good friend Mike Powell at Occoquan Regional Park, Fairfax County, Virginia USA.

Male

The first individual is a male, as indicated by his “indented” hind wings, and terminal appendages. Notice the epiproct for Brown Spiketail is a wide “plate” that spans both cerci, as shown in the full-size version of the following photo.

The next individual is also male, as indicated by his hamules, located below abdominal segments two and three (S2 and S3).

Female

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

Credits

Thanks to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, for confirming my tentative identification of the gender of the first and last individuals.

Phenology

Phenology (noun) is defined as “the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.”

There is an annual cycle of odonate activity that can be subdivided into three broad categories: Early Season (spring); Mid-season (summer); and Late Season (fall).

Brown Spiketail is an “Early Season” species for locations in the Commonwealth of Virginia. I have noticed that the adult flight period for a given species of odonate in Northern Virginia tends to lag behind Amherst County, where my good friend Mike Boatwright (Mike B) lives, by about one-to-two weeks. When Mike B reported his first sighting of Brown Spiketail on 24 April in Amherst County, I knew it wouldn’t be long until Brown Spiketail would be flying in Fairfax County. Eight (8) days later, Mike Powell and I spotted our first-of-season Brown Spiketail dragonflies. Thanks for the heads-up, Mike B!

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Test shots: “Generic Baskettail?”

February 15, 2019

larva/nymph in the Family Corduliidae (Emeralds) was collected by Bob Perkins on 02 December 2017 from a pond in Orange Park, Florida (USA). The larva died before it metamorphosed into an adult.

Test shots of this beautifully preserved specimen were taken using a small-ish aperture of f/11 for greater depth of field. The following photos are “one-offs,” that is, not composite images.

Dorsal

A single focus point — located on the thorax (specifcally, the “shoulder pad” along the right side of the body) — was used to shoot this photo. The specimen has enough “relief” that focus on the wing pads and dorsal hooks is slightly soft. This view of the larva is a good candidate for focus-stacking.

The terminal appendages (cerci, epiproct, paraprocts) are shown clearly in the following photo.

“Generic Baskettail” larva (preserved specimen) | Orange Park, FL USA

Bob’s best guess of the identity of the specimen is Epitheca sp., either Common Baskettail (Epitheca cynosura) or Prince Baskettail (Epitheca princeps).

Whenever I see an odonate larvae/exuviae with long legs, my first thought is Family Macromiidae (Cruisers). Then I check for a horn on top of the head, a key field mark for Cruisers. Look closely at the dorsal view of the larva and I think you’ll agree with me there appears to be a horn on the head. I would like to take close-up photos of the head and key out the specimen in order to determine its identity. In the meantime, my best guess is Stream Cruiser (Didmops transversa) as indicated by the lateral spines on abdominal segment nine (S9) and the absence of a dorsal hook on S10.

Ventral

The ventral side of the specimen has almost no “relief,” so a “one-off” focused on the thorax looks fairly good from head-to-tail.

“Generic Baskettail” larva (preserved specimen) | Orange Park, FL USA

Related Resource: “Generic Baskettail” (definitely not a Cruiser)

Tech Tips

The following equipment (shown below) was used to shoot the preceding photos: Fujifilm X-T1 digital camera; Fujifilm MCEX-16 extension tube; Fujinon XF80mm macro lensGodox XProF TTL Wireless Flash Trigger for Fujifilm camerasGodox TT685F Thinklite TTL Flash for Fujifilm CamerasGodox TT685C Thinklite TTL Flash for Canon Cameras fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier; and a Canon 580EX II Speedlite mounted on a Godox X1R-C TTL Wireless Flash Trigger Receiver for Canon. A new Godox TT685O Thinklite TTL Flash for Olympus/Panasonic Cameras was added to an array of radio-controlled external flash units used to light the specimen. All flashes were set for Manual Mode at 1/128 power.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the final output.

Copyright © 2019 Walter Sanford. All rights reserved.

More composite images: P. obscurus exuvia

February 6, 2019

The following focus-stacked composite images show dorsal- and ventral views of the exuvia from a Common Sanddragon (Progomphus obscuruslarva that was collected and reared by Bob Perkins.

Here are some personal observations after examining the specimen carefully.

The front- and middle legs block the mentum (prementum). This specimen is a good candidate for rehydrating the exuvia and reposing its legs.

Related Resource: Composite image: Progomphus obscurus exuvia.

Tech Tips

Six (6) photos were used to create the first focus stack; seven (7) photos were used for the second. A single focus point was positioned over select anatomical features, working from back-to-front; photos were taken at each point of interest.

The following equipment was used to shoot all of the photographs for the two focus-stacked composite images, shown above: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to create the focus-stacked composite images, as well as spot-heal and sharpen the final output.

Copyright © 2019 Walter Sanford. All rights reserved.

“Post Focus” images: Shadow Darner dragonfly

January 30, 2019

Bob Perkins collected and reared a Shadow Darner dragonfly (Aeshna umbrosa) larva/nymph. This blog post features two focus-stacked composite images of a beautifully preserved specimen of the adult that emerged from the larva.

Each composite image was created from 30 TIF files extracted from a one-second MP4 video of the subject, “photographed” using my new Panasonic Lumix DMC-FZ300 digital camera set for “Post Focus.”

This individual is a male, as indicated by his terminal appendages and “indented” hind wings (shown above). All male dragonflies have three terminal appendages, collectively called “claspers”: the two cerci are missing (they broke off the terminal end of the abdomen during shipping); the epiproct is intact.

Shadow Darner (Aeshna umbrosa) | dorsal-lateral view

Takeaways

Perhaps the biggest takeaway from on-going experimentation with Panasonic “Post Focus” is that the process continues to impress — it works quickly (typically one second or so) and works well, using lightweight, inexpensive equipment for making composite images of acceptable quality.

What’s not to like? The obvious answer: The image quality isn’t as high as comparable images created using HEAVY and EXPENSIVE camera gear in the controlled environment of a photo studio. On the other hand, I know from experience I’m unlikely to lug all of that gear into the field. I call it a BIG WIN to have found a relatively lightweight, inexpensive camera kit that does essentially the same job almost as well!

The next test: Use adult dragonflies in the wild as the subject. Regrettably, that will have to wait until the first odonates begin emerging during early spring.

Related Resources

Tech Tips

The following equipment was used to shoot the “photos” for creation of the composite images, shown above: Panasonic Lumix DMC-FZ300 digital camera set for “Post Focus“; and two Sunpak LED-160 Video Lights.

Adobe Photoshop CC 2017 was used to create the preceding focus-stacked composite images, as well as spot-heal and sharpen the final output.

Copyright © 2019 Walter Sanford. All rights reserved.


%d bloggers like this: