Posts Tagged ‘hamules’

Mocha Emerald dragonfly claspers

July 13, 2017

Mocha Emerald dragonfly (Somatochlora linearis) was spotted along a small creek at a remote location in the forest at Huntley Meadows Park. This individual is a male, as indicated by his terminal appendages and hamules.

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”).

09 JUL 2017 | Huntley Meadows Park | Mocha Emerald (male)

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

09 JUL 2017 | Huntley Meadows Park | Mocha Emerald (male)

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

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.

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.

09 JUL 2017 | Huntley Meadows Park | Mocha Emerald (male)

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

Technique Hint: Did you notice that the “focus” of each photo (not to be confused with the focus point) is shown against a lighter background? That’s no accident — I composed each shot that way. As a result, the terminal appendages (cerci and epiproct) are much easier to see in the first two photos than the last shot, in which the composition highlights the hamules.

Copyright © 2017 Walter Sanford. All rights reserved.

Allegheny River Cruiser dragonfly (male)

June 19, 2017

An Allegheny River Cruiser dragonfly (Macromia alleghaniensis) was netted by Mike Blust at Hardware River Wildlife Management Area, Fluvanna County, Virginia USA.

The complete yellow ring around abdominal segment seven (S7) is a distinctive field marker for this species. This individual is a male, as indicated by his hamules and terminal appendages.

Allegheny River Cruiser is a good candidate for netting, that is, if you want to get a close look at one.

Males fly rapidly up and down streams, mostly but not always near shore, usually quite low… . Cruise up and down roads through woodland, in sun and shade, or fly up higher into forest canopy. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 7313-7315). Princeton University Press. Kindle Edition.

The following map shows all official records for Allegheny River Cruiser in the United States of America. Notice the records are roughly coincident with the Allegheny Mountains, from which part of the common name for this species is derived.

Source Credit: Abbott, J.C. 2006-2017. OdonataCentral: An online resource for the distribution and identification of Odonata. Available at http://www.odonatacentral.org. (Accessed: June 13, 2017).

Allegheny River Cruiser is a new species of dragonfly for my life list.

Tech Tips

The photo was taken using a Fujifilm X-T1 digital camera, Fujinon 55-200mm zoom lens, and Fujifilm EF-X500 shoe mount flash.

My camera had a mysterious meltdown when I was trying to photograph the dragonfly in Mike Blust’s hand. Sincere thanks to Mike for his extraordinary patience while I was troubleshooting the problem under extreme pressure.

Editor’s Note

Sincere thanks to Mike Boatwright for taking me to a couple of odonate-hunting localities along the James River, including Hardware River WMA (see map, shown below) and Columbia Boat Landing, Cumberland County, Virginia.

Copyright © 2017 Walter Sanford. All rights reserved.

Cobra Clubtail external reproductive anatomy

May 28, 2017

I liked to make paper- and plastic models when I was a child. Seems like the directions for assembling many models — not that anyone reads the directions — always started by saying something like “Insert Tab A in Slot B.”

Oddly enough, that line reminds me of how odonates copulate, in general, and Cobra Clubtail dragonflies (Gomphurus vastus) in particular.

Male

The hamules are “Tab A.”

Female

The subgenital plate is “Slot B.”

Putting it all together

Insert Tab A in Slot B. That’s the PG-rated version of how Cobra Clubtail dragonflies copulate in order to reproduce.

The Backstory

There is an annual mass emergence of Cobra Clubtails during the first week-or-two of May at Riverbend Park. It’s a spectacular event worth seeing firsthand!

The following photo shows a dead female, one of several Cobra Clubtails that were trampled by groups of elementary school children visiting the park on 09 May 2017. Her premature death saddens me because it was avoidable — the students should have been warned to watch their step because there were lots of Cobra Clubtails perching on the ground almost everywhere.

In the hope the female didn’t die in vein, I reluctantly decided to photograph the corpse in order to illustrate her external reproductive anatomy.

Editor’s Note: Sincere thanks to Dennis Paulson for help in identifying the female parts on the ventral side of abdominal segments eight and nine (S8-9).

Copyright © 2017 Walter Sanford. All rights reserved.

Because it’s fun!

May 16, 2017

Why do I hunt odonates, that is, dragonflies and damselflies? I like being outdoors, visiting beautiful natural places. I like honing my skills as a wildlife photographer. Most importantly, it’s fun! I like the challenge of finding uncommon species, and the thrill of making new discoveries.

A Cobra Clubtail dragonfly (Gomphurus vastus) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and indented hind wings.

The male was perching on colorful kayaks stored in a wooden rack near the boat ramp. Notice the natural coloration of the dragonfly was affected by light reflected from the kayaks. That’s OK since this photo set is all about fun, right?

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

Can you say “hamules?” Males of many species in the Family Gomphidae (Clubtails) have prominent secondary sex organs.

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

09 MAY 2017 | Riverbend Park | Cobra Clubtail (male)

Tech Tips: I carried two digital cameras during the trip to Riverbend Park: a Panasonic DMC-FZ150 superzoom bridge camera plus Canon 580EX Speedlite, my go-to kit for photowalking; as well as my Fujifilm X-T1Fujinon XF55-200mm zoom lens, and Fujifilm EF-X500 shoe mount flash. Since Fujifilm digital cameras are well-known for capturing vivid color, the X-T1 was the camera of choice for this colorful scene.

Editor’s Note: 16 May is the one-year anniversary of my first visit to Riverbend Park to see the annual mass emergence of Cobra Clubtail dragonflies that occurs during the first two weeks in May.

Copyright © 2017 Walter Sanford. All rights reserved.

Epitheca cynosura exuvia

April 26, 2017

On 13 April 2017, a late-stage emergent teneral female Common Baskettail dragonfly (Epitheca cynosura) was observed at Painted Turtle Pond during a photowalk around Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Several dragonfly exuviae were collected near the same location as the emergent teneral female. All of the exuviae look identical, although there is some variation in size. A two-step process was used to verify the genus and species for one of the larger exuvia.

  • Determine the family.
  • Determine the genus and species.

This specimen is approximately 22 mm (~0.87 in) in length.

Step 1. Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06). Here’s the decision tree used to identify the exuvia as a member of the Family Corduliidae (Emeralds).

  • The specimen has a mask-like labium that covers the face, characteristic of four families: Cordulegastridae (Spiketails); Corduliidae (Emeralds); Libellulidae (Skimmers); and Macromiidae (Cruisers).
  • There is no horn on top of the face-head, characteristic of Macromiidae, so it’s not a cruiser.
  • Cordulegastridae has jagged crenulations on its labium, so it’s not a spiketail. The crenulations for Corduliidae and Libellulidae look similar.
  • Look at the anal pyramid to differentiate Corduliidae and Libellulidae [See Photo No. 7.]: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts. [Editor’s Note: It’s probably Libellulidae if the cerci are less than half the length of the paraprocts.]

In summary, the exuvia has a mask-like labium with relatively smooth crenulations, no horn on its face-head, and the cerci are more than half as long as the paraprocts, confirming that the specimen is a member of Family Corduliidae (Emeralds).

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

Notice that dorsal hooks are present and well developed on most abdominal segments.

No. 4 | Common Baskettail (Epitheca cynosura) | exuvia (dorso-lateral)

A lateral view of the exuvia provides a good look at the labium, also known as 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.

The white filaments that extend from the split in the thorax (as shown in Photo No. 1-7) are breathing tubes, artifacts of the unique respiratory system of dragonfly nymphs.

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

A closer view of the head shows two “bumps” that may be a pair of tubercles.

Step 2. Genus and species

Characters from Identification Keys to Northeastern Anisoptera Larvae, dichotomous keys compiled by Ken Soltesz, were used to identify the genus and species for the exuvia. Although palpal/mental setae were not examined, all other characters match Epitheca cynosura.

dichotomous key: a key for the identification of organisms based on a series of choices between alternative characters. Source Credit: Merriam-Webster Dictionary.

Alternate Key to the Genera of the Family Corduliidae, p. 29.

Key to the species of the genus (subgenus) Tetragoneuria, p. 32.

No. 7 | Common Baskettail (Epitheca cynosura) | exuvia (anal pyramid)

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

The last photo shows a ventral view of the exuvia. The vestigial hamuli located between abdominal segments two and three (S2-3) strongly suggests this individual is a male, therefore this specimen probably is not the same exuvia from which the teneral female emerged.

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

Tech Tips:

The following equipment was used to shoot all of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Canon EF100mm f/2.8L Macro lens (set for manual focus) plus a Kenko 20mm macro automatic extension tube; Canon 580EX II external flash tethered to the camera by a coiled six-foot Vello Off-Camera TTL Flash Cord for Canon Cameras, off-camera, in manual mode; the Canon flash optically triggered a small Nissin i40 external flash (in SF mode) used for backlight; and a Sunpak LED-160 Video Light with a white translucent plastic filter used for side light.

Adobe Photoshop CC 2017 was used to annotate selected images.

Related Resources:

Editor’s Note: Sincere thanks to Sue Gregoire, Kestrel Haven Migration Observatory, for verifying my tentative identification, and for sharing some good odonate nymph knowledge regarding vestigial hamuli!

Copyright © 2017 Walter Sanford. All rights reserved.

Slaty Skimmer dragonflies (mating pair)

March 7, 2017

Odonates (dragonflies and damselflies) are aquatic insects that spend most of their life as larvae that live in water; this stage of their life cycle can last from a few months to a few years, depending upon the species. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

A mating pair of Slaty Skimmer dragonflies (Libellula incesta) was spotted at Painted Turtle Pond, Occoquan Bay National Wildlife Refuge (OBNWR), Prince William County, Virginia USA. This pair is “in wheel”: the male is on the upper-left; the female on the lower-right.

A mating pair of Slaty Skimmer dragonflies (Libellula incesta) spotted at Painted Turtle Pond, Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This pair is "in wheel."

18 JUN 2016 | OBNWR | Slaty Skimmer (mating pair, “in wheel“)

All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

Copyright © 2017 Walter Sanford. All rights reserved.

American Rubyspot damselfly (male)

January 24, 2017

An American Rubyspot damselfly (Hetaerina americana) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a male, as indicated by his coloration and hamules.

One and done. That’s the way some wildlife photographers shoot a subject. I like to “work the shot,” that is, shoot the subject from all angles and in different positions.

In this case, the damselfly was perching over deep water. I waded into the water as far as I could go in my knee-high green wellies and made the best of a less than ideal situation.

Since the subject never moved from his perch above the water, I moved so that my viewpoint featured different backgrounds. Also, the damselfly changed position slightly during the shoot. Although all of the photos in this set are similar, each one is different in the way it looks and feels.

Copyright © 2017 Walter Sanford. All rights reserved.

Hamules

December 2, 2016

Russet-tipped Clubtail dragonfly (Stylurus plagiatus) was spotted during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR). This individual is a male, as indicated by the large russet-colored club at the end of his abdomen and by his prominent 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.

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

Like many species of Family Gomphidae (Clubtail dragonflies), the hamules of male Russet-tipped Clubtails are conspicuous — there’s nothing subtle about these guys!

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Meme used with permission from Jacki Morrison (Minnesota Dragonflies).

The preceding meme features an outtake from “War of the Coprophages,” an episode of The X-Files (TV Series). Fox Mulder is an FBI agent who investigates paranormal activity; Dr. Bambi Berenbaum is a fictional scientist named after American entomologist Dr. May Berenbaum. I wasn’t into dragonflies when the episode aired in 1996, so the snippet of risque dialog about cockroaches (quoted in the meme) was lost on me. In retrospect, it’s clear that at least one of the writers/consultants for the episode must be quite familiar with dragonflies!

Copyright © 2016 Walter Sanford. All rights reserved.

Time to mate

November 13, 2016

In a recent blog post, I wrote…

Both Blue-faced Meadowhawks and Autumn Meadowhawks are classified as fall species of odonates. In the mid-Atlantic United States, meadowhawks seem to disappear for several months after they emerge during early summer and reappear during fall. Where do they go? No one knows for sure. I speculate Blue-faced Meadowhawks and Autumn Meadowhawks are arboreal species of dragonflies that return to the ground/water when it’s time to mateSource Credit: More previews of coming attractions.

Fall is the time to mate for Autumn Meadowhawk dragonflies (Sympetrum vicinum), as you can see in the following photo.

A mating pair of Autumn Meadowhawk dragonflies (Sympetrum vicinum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is "in wheel."

06 NOV 2016 | HMP | Autumn Meadowhawk (mating pair, “in wheel“)

This mating pair is “in wheel.” All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

Odonates (dragonflies and damselflies) are aquatic insects. Most of their life is spent underwater as a nymph. The life span of a nymph depends upon the species: it’s a few months for some species; a few years for other species. Individual adult odonates — like the ones we see flying around Huntley Meadows Park (HMP) — usually live one- to two months, although many different individuals from the same species may be seen for longer periods of time. Adult odonates have one goal: mate in order to reproduce. When fertilized eggs are laid in water, the circle of life comes full circle: eggs; prolarvae; larvae; emergence/adult males and females; mating pairs; males guide females to egg-laying sites (some species, such as Autumn Meadowhawk) or solo females lay eggs (all other species).

Copyright © 2016 Walter Sanford. All rights reserved.

Time to mate

September 18, 2016

A mating pair of Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) was spotted at a vernal pool in Huntley Meadows Park (HMP). The vernal pool, currently dry, is the same one where teneral Blue-faced Meadowhawks were observed during late-May and early-June 2016.

This mating pair is “in wheel.” All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

A mating pair of Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is "in wheel." The female is an andromorph.

15 SEP 2016 | HMP | Blue-faced Meadowhawks (mating pair, “in wheel“)

Some species of dragonflies display sexual dimorphism; females are polymorphic for a smaller subset of those species. Andromorph females are male-like in color; heteromorph females are duller in color than males.

Notice the female in this mating pair is an andromorph. Female andromorphs are less common than heteromorphs.

A mating pair of Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is "in wheel." The female is an andromorph.

15 SEP 2016 | HMP | Blue-faced Meadowhawks (mating pair, “in wheel“)

Copyright © 2016 Walter Sanford. All rights reserved.


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