Perithemis tenera exuviae

December 6, 2016

Several unknown dragonfly exuviae were collected from the Potomac River, Fairfax County, Virginia USA. The specimens have a mask-like labium (not flat) with smooth crenulations, indicating these exuviae are members of Family Libellulidae (Skimmers).

A dichotomous key was used to tentatively identify the exuviae as Eastern Amberwing dragonfly (Perithemis tenera), as indicated by the following morphological characteristics.

  • The cerci (sing. cercus) are slightly less than half the length of the paraprocts.
  • Dorsal hooks are clearly visible on abdominal segments four through nine (S4-9), plus a “nub” that is visible on segment three (S3).
  • Lateral spines are clearly visible on abdominal segments eight and nine (S8-9).

These specimens are the first odonate exuviae that I was able to identify to the species level. Sincere thanks to Sue Gregoire, Kestrel Haven Migration Observatory, for verifying my preliminary observations and tentative identification!

No. 1

A pair of Eastern Amberwing dragonfly (Perithemis tenera) exuviae collected from the Potomac River, Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA.

07 JUL 2016 | Potomac River | Eastern Amberwing (exuviae)

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

Each specimen is approximately 1.4 cm (~0.6″) in length and approximately 0.6 cm (~0.2″) in maximum width. In Photo No. 1, the specimen shown on the left is an emergent nymph that was stuck in its exuvia. The white filaments that extend from the split in the thorax (as shown in Photo No. 1-3) are breathing tubes, artifacts of the unique respiratory system of dragonfly nymphs.

No. 2

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia collected from the Potomac River, Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA.

07 JUL 2016 | Potomac River | Eastern Amberwing (exuvia, dorsal view)

No. 3

The eyes are relatively small and widely separated. Notice the mask-like labium (sometimes referred to as “spoon-shaped”) with smooth crenulations along the margins between two lateral lobes.

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia collected from the Potomac River, Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA.

07 JUL 2016 | Potomac River | Eastern Amberwing (exuvia, head-on)

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

No. 4

One of the keys to identifying skimmer dragonflies to the species level is to carefully examine the anal pyramid (see S10, shown below), including the cerci (sing. cercus) and paraprocts.

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia collected from the Potomac River, Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA.

07 JUL 2016 | Potomac River | Eastern Amberwing (exuvia, anal pyramid)

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

Tech Tips:

The following equipment was used to shoot the preceding photographs:

Adobe Photoshop CC 2017 was used to annotate selected images.

Related Resources:

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

Assuming the convention of labeling the two branches of each dichotomy as “a” and “b”, e.g. 1a, 1b, etc., a list of branches in the decision tree that I used to identify the species of the dragonfly exuviae is as follows: 1b; 4b; 5a; 6a BINGO!

Copyright © 2016 Walter Sanford. All rights reserved.

Painted Skimmer dragonflies (males)

December 4, 2016

Several Painted Skimmer dragonflies (Libellula semifasciata) were spotted at a vernal pool in Huntley Meadows Park. All of these individuals are males, as indicated by their terminal appendages.

Sometimes you need to stop and smell the “soft rush” (Juncus effusus), the common name for the shoreline/emergent plant with a light green round stem and brownish-green flowers shown in the following photo. Soft rush is common in wetland areas.

You may be wondering, “Do dragonflies have a sense of smell?” The surprising answer can be found in an interesting article from Science magazine: Dragonflies Lack ‘Smell Center,’ but Can Still Smell.

The second and third photos in this gallery show the same male. Regular readers of my photoblog know I love a good head-tilt, shown below.

The following male must be a member of the Democratic Party, based upon his viewpoint to the left. Hah! I couldn’t resist a little good-natured jab at my friends from the opposition party who are still suffering over the outcome of the recent USA presidential election.

The last one’s for you, Michael Powell. Turns out it’s a rare photo (well, rare for me) shot in Aperture priority mode — looking along the barrel of the body, thought I’d need more depth of field.

Copyright © 2016 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.

When things go wrong

November 30, 2016

One week after I witnessed the miraculous metamorphosis of an emergent male Common Sanddragon dragonfly (Progomphis obscuris), I was reminded that a lot can go wrong during emergence. Like the old blues standard says…

When things go wrong, go wrong with you
It hurts me too.

An emergent nymph was spotted during a photowalk along Dogue Creek at Wickford Park. The nymph was in the same position hours later, so I’m sad to say the dragonfly was stuck in its exuvia.

Related Resource: Common Sanddragon dragonfly (emergent male), a blog post by Walter Sanford featuring a time-series of photographs documenting the metamorphosis of an emergent male Common Sanddragon dragonfly on 01 June 2016 at Wickford Park.

Copyright © 2016 Walter Sanford. All rights reserved.

Common Sanddragon dragonfly (male)

November 28, 2016

A Common Sanddragon dragonfly (Progomphus obscurus) was spotted during a photowalk along Dogue Creek at Wickford Park, Fairfax County, Virginia USA. This individual is a male, as indicated by his coloration and terminal appendages.

Like all male clubtail dragonflies, the hindwings of male Common Sanddragons are “indented” near the body. This distinctive field marker is shown well by the first, fourth, and last photos in this gallery.

Half of the photographs in this set are full-frame, that is, uncropped. Like the next photo. Knee-high rubber boots enabled me to photowalk the stream channel, allowing me to get much closer to the subject. This guy is the second of at least five adult males I was able to photograph at close range during the outing.

Some people imagine the yellow markings along the abdomen look like small burning candles.

Copyright © 2016 Walter Sanford. All rights reserved.

New late-date for Familiar Bluet

November 26, 2016
A Familiar Bluet damselfly (Enallagma civile) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

18 NOV 2016 | Huntley Meadows Park | Familiar Bluet (male)

A Familiar Bluet damselfly (Enallagma civile) was spotted near a vernal pool located in Huntley Meadows Park. This individual is a male, as indicated by his black and blue coloration and by his terminal appendages.

A Familiar Bluet damselfly (Enallagma civile) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

18 NOV 2016 | Huntley Meadows Park | Familiar Bluet (male)

18 November is a new personal late-date for Familiar Bluet at Huntley Meadows Park. As it turns out, another male Familiar Bluet was spotted by Michael Powell on the same date at another location in the park. The record late-date for Familiar Bluet in the Commonwealth of Virginia is 27 December, set in 2015.

Copyright © 2016 Walter Sanford. All rights reserved.

Wildlife watching “Wildlife Watching” sign

November 24, 2016

There is a “Wildlife Watching” sign located along the boardwalk at Huntley Meadows Park, near the observation tower overlooking the central wetland area.

Notice the Autumn Meadowhawk dragonfly (Sympetrum vicinum) perching on the signage. This individual is a male, as indicated by the bright red coloration of his abdomen and by his terminal appendages.

Regular readers of my photoblog know I love a good head-tilt! Doesn’t this guy look jaunty?

Autumn Meadowhawks like to rest on sunlit surfaces like the sign (and boardwalk) in order to absorb thermal energy.

Hey folks, you’re looking the wrong way — there’s a big dragonfly behind you!

The hemi-marsh at Huntley Meadows Park is a good habitat for many species of odonates, including Autumn Meadowhawk.

I spent about 30 minutes watching the sign, waiting for the dragonfly to land at different places on the sign. During that time, several people passed the sign but no one noticed the dragonfly. As the sign says, “Take time to look carefully” when you visit a wildlife watching park.

Editor’s Note: On the traditional day when we give thanks for our many blessings, I am especially thankful for the opportunity to be a frequent and careful observer of the natural beauty of the hemi-marsh at Huntley Meadows Park, and for many good friends with whom I share the experience. Happy Thanksgiving!

Copyright © 2016 Walter Sanford. All rights reserved.

Variable Dancer (mating pair, “in heart”)

November 23, 2016

A mating pair of Variable Dancer damselflies (Argia fumipennis violacea) was spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge (JMAWR). This pair is “in heart“: the male is on the upper-left; the female on the lower-right.

A mating pair of Variable Dancer damselflies (Argia fumipennis violacea) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This pair is "in heart."

14 JUN 2016 | JMAWR | Variable Dancer (mating pair, “in heart“)

In the following photo, the male is on top; the female on the bottom.

A mating pair of Variable Dancer damselflies (Argia fumipennis violacea) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This pair is "in heart."

14 JUN 2016 | JMAWR | Variable Dancer (mating pair, “in heart“)

The taxonomic classification of Variable Dancer is as follows: Order Odonata (Dragonflies and Damselflies); Suborder Zygoptera (Damselflies); Family Coenagrionidae (Narrow-winged Damselflies); Genus Argia (Dancers); Subspecies Argia fumipennis violacea (Violet Dancer).

Variable Dancer is a habitat generalist that can be found almost anywhere there is water. Mature males are easy to recognize due to their unique coloration — there are no other species of violet damselflies found in the eastern one-third of the United States. Female Variable Dancers, like many female odonates, are more challenging to identify than males.

It’s helpful to get shots of mating pairs of damselflies, especially “in tandem,” since males and females of the same species can look quite different. The excellent high-resolution digital scans by Gayle and Jeanelle Strickland, listed under “Related Resources” (below), provide clear views of male and female Variable Dancer damselflies.

Related Resources: High-resolution digital scans created by Gayle and Jeanelle Strickland.

Copyright © 2016 Walter Sanford. All rights reserved.

Blue-fronted Dancer

November 21, 2016
A Blue-fronted Dancer damselfly (Argia apicalis) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

14 JUN 2016 | JMAWR | Blue-fronted Dancer (male)

These two photos show one of many Blue-fronted Dancer damselflies (Argia apicalis) spotted during a photowalk around Mulligan Pond, Jackson Miles Abbott Wetland Refuge (JMAWR). This individual is a male, as indicated by his coloration and terminal appendages.

A Blue-fronted Dancer damselfly (Argia apicalis) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

14 JUN 2016 | JMAWR | Blue-fronted Dancer (male)

The taxonomic classification of Blue-fronted Dancer is as follows: Order Odonata (Dragonflies and Damselflies); Suborder Zygoptera (Damselflies); Family Coenagrionidae (Narrow-winged Damselflies); Genus Argia (Dancers); Species apicalis.

Related Resources: High-resolution digital scans created by Gayle and Jeanelle Strickland.

Copyright © 2016 Walter Sanford. All rights reserved.

Southern Spreadwing at MNWP

November 19, 2016

Many Southern Spreadwing damselflies (Lestes australis) were observed around the stormwater management pond located at Mason Neck West Park (MNWP) during Fall 2016. The following gallery, presented in chronological order, showcases select specimens spotted during several photowalks at the park.

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

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a female.

27 SEP 2016 | MNWP | Southern Spreadwing (female)

The next two photos show a couple of males, as indicated by their coloration and terminal appendages.

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | MNWP | Southern Spreadwing (male)

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | MNWP | Southern Spreadwing (male)

The following photo shows a mating pair “in tandem,” the post-copulatory phase when the male guides the female to egg-laying sites. The male is on top; the female on the bottom.

A mating pair of Southern Spreadwing damselflies (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This pair is in tandem.

27 SEP 2016 | MNWP | Southern Spreadwing (mating pair, in tandem)

The female uses her ovipositor to insert eggs into vegetation (endophytic oviposition).

A mating pair of Southern Spreadwing damselflies (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This pair is in tandem; the female is laying eggs (oviposition).

27 SEP 2016 | MNWP | Southern Spreadwing (mating pair, in tandem)

More males were spotted on consecutive days in early-October.

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male.

03 OCT 2016 | MNWP | Southern Spreadwing (male)

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male.

04 OCT 2016 | MNWP | Southern Spreadwing (male)

The last individual is a female that I found resting/roosting in a field of grasses, quite a distance from the water. As it turns out, this female — spotted on 14 October 2016 — is also the last Southern Spreadwing observed at Mason Neck West Park during 2016. It’s worth noting the late-date for Southern Spreadwing at MNWP is consistent with the late-date of 15 October 2015 for the same species at Huntley Meadows Park.

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a female.

14 OCT 2016 | MNWP | Southern Spreadwing (female)

A Southern Spreadwing damselfly (Lestes australis) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a female.

14 OCT 2016 | MNWP | Southern Spreadwing (female)

Copyright © 2016 Walter Sanford. All rights reserved.


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