Posts Tagged ‘terminal appendages’

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.

Black-shouldered Spinyleg (female)

August 13, 2021

A Black-shouldered Spinyleg dragonfly (Dromogomphus spinosus) was spotted by Michael Powell during a photowalk with me along a mid-size 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.

05 AUG 2021 | PNC. Wm. County | Black-shouldered Spinyleg (female)

We followed the female from one location…

05 AUG 2021 | PNC. Wm. County | Black-shouldered Spinyleg (female)

to another.

05 AUG 2021 | PNC. Wm. County | Black-shouldered Spinyleg (female)

I was able to take no more than three shots at each perch before she moved on to the next stop.

05 AUG 2021 | PNC. Wm. County | Black-shouldered Spinyleg (female)

Habitat

I’m not sure I’d call Black-shouldered Spinyleg a habitat specialist. I’ve seen and photographed D. spinosus along small streams in the forest, mid-size streams (like the one in this post), and large rivers.

Habitat: Rocky and muddy streams and rivers from small to large, more often in woodland. Also in rocky lakes in northern part of range. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 6416-6417). Princeton University Press. Kindle Edition.

Range map

The following map shows all official records for Dromogomphus spinosus in the United States of America. Given the wide range of lotic habitats where Black-shouldered Spinyleg is found, I’m puzzled by the fact that the species isn’t more widespread than it appears to be.

Related Resource: All posts in my blog tagged with the words “Black-shouldered Spinyleg dragonfly.”

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.

 

Tiger Spiketail dragonfly (male)

August 7, 2021

Tiger Spiketail dragonfly (Cordulegaster erronea) was captured along a small stream at an undisclosed location in Prince William County, Virginia USA. The specimen was photographed and released unharmed.

The first few images show Michael Powell, my good friend and photowalking buddy, holding the dragonfly while I shot some photographs.

05 AUG 2021 | Prince William County, VA | Tiger Spiketail (male)

This individual is a male, as indicated by his hamules, “indented” hind wings, and terminal appendages.

05 AUG 2021 | Prince William County, VA | Tiger Spiketail (male)

What a handsome face! Cue “Eye Of The Tiger” by Survivor.

05 AUG 2021 | Prince William County, VA | Tiger Spiketail (male)

The next image shows me holding the dragonfly so that Mike could take some photographs.

Photo used with written permission from Michael Powell.

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

Up, up, and away!

The last photograph shows the Tiger Spiketail “posed” au naturel on the trunk of a fallen tree. Mike and I chose that spot because it was one of only a few sunny places along the small forest stream. The Tiger flew away almost immediately after I released him, headed toward the tree canopy. Mike had time for one clear shot. Good thing, ‘cuz I had no opportunity to get a shot.

Photo used with written permission from Michael Powell.

The backstory

I went on my first Tiger safari during July 2018 when I visited a location in Fairfax County, Virginia that a friend shared with me in strictest confidence. Although I saw several Tiger Spiketail dragonflies, every individual was in flight and I was unable to shoot still photos and/or video — they were gone by the time I reached for my camera!

Every year for the next few years, the story was similar — I saw Tigers but had no photos/videos to verify my sightings. Eventually I came to the conclusion that I would need to capture a specimen with an insect net in order to take photographs.

Let me be perfectly clear — all things being equal I would prefer to photograph dragonflies perching naturally rather than netting them. Sometimes, as in this case, netting is the better way to go.

Rest assured I have great respect for the rare- to uncommon species of odonates. The Tiger Spiketail featured in this post was held in captivity no longer than absolutely necessary, and was handled gently at all times.

Our strategy

Mike and I arrived at the stream site sometime after 10 a.m. While I setup my 18” diameter collapsible insect net, Mike took the point a little farther downstream to look for a Tiger approaching our location. No more than 10 minutes after I was in position alongside the stream, Mike spotted a Tiger flying upstream in our direction.

I waited until the Tiger had almost reached the place where I was standing before I swung my net forward smoothly and was psyched to see the dragonfly go all the way into the net. I said to Mike, “I got it!”

From that point, I worked quickly to gently remove the dragonfly from the net so that Mike and I could take some photographs of this rare species.

Range map

The following map shows all official records for Cordulegaster erronea in the United States of America. Tiger Spiketail is a habitat specialist that is challenging to find.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Ebony Jewelwing damselfly (male)

July 30, 2021

An Ebony Jewelwing damselfly (Calopteryx maculata) was spotted along a small stream located in Occoquan Regional Park, Fairfax County, Virginia USA.

05 JUN 2021 | Fairfax County, VA | Ebony Jewelwing (male)

This individual is a male, as indicated by his all black wings and terminal appendages.

05 JUN 2021 | Fairfax County, VA | Ebony Jewelwing (male)

Habitat

It’s easy to find Ebony Jewelwing. Look for a small stream in the forest.

Slow-flowing woodland streams, usually associated with herbaceous vegetation. Tend to be more at rapids when that habitat is present. Occur on open banks when trees nearby (trees essential for roosting at night). May be abundant at small streams in woods where very few other species are present. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 1249-1251). Princeton University Press. Kindle Edition.

Copyright © 2021 Walter Sanford. All rights reserved.

More Bar-winged Skimmers (males)

July 23, 2021

At least two male Bar-winged Skimmer dragonflies (Libellula axilena) were spotted along the shoreline of a small pond at an undisclosed location in Prince William County, Virginia USA.

It’s possible all of the photos featured in this blog post are of the same mature male that is featured in another recent post, as indicated by a distinctive pattern of spider web strands on the wings of the dragonfly.

Look closely along the leading edge of the wings. Notice the dark bars from which the common name for this species is derived are almost invisible.

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

For what it’s worth, the first and last photos in this set are my favorite.

Related Resource: Bar-winged Skimmer dragonfly (male).

Copyright © 2021 Walter Sanford. All rights reserved.

Gray Petaltail dragonfly (male)

July 13, 2021

A Gray Petaltail dragonfly (Tachopteryx thoreyi) was observed during a photowalk with Michael Powell along the shoreline of a small pond at an undisclosed location in Prince William County, Virginia USA.

Mike spotted the Gray Petaltail first, when we were on opposite sides of the pond. Mike was able to shoot a few photos before the dragonfly flew away and Mike moved on. I thought Mike gave up on the subject too quickly so I decided to use one of my tried and true strategies for finding and photographing odonates: Sit in a good spot and wait for the game to come to me.

I walked around to the other side of the pond and sat down on my small, lightweight camp stool about 12-15 feet from the place where Mike had seen the Gray Petaltail. Sure enough, the dragonfly returned to the same perch soon afterward!

The first photo is the “record shot,” that is, get a shot, any shot.

17 JUN 2021 | PNC. Wm. County | Gray Petaltail (male)

This individual is a male, as indicated by his “indented” hind wings and terminal appendages.

17 JUN 2021 | PNC. Wm. County | Gray Petaltail (male)

The dragonfly would perch briefly, then fly away.

17 JUN 2021 | PNC. Wm. County | Gray Petaltail (male)

The male dragonfly did the same thing repeatedly, always returning to a slightly different perch each time. Turns out he was hunting for food.

17 JUN 2021 | PNC. Wm. County | Gray Petaltail (male)

I would describe T. thoreyi as an “ambush predator” — sometimes Gray Petaltail hunts for prey by waiting for other flying insects to pass by and ambushing them aerially when they do. Like the crane fly shown below that the Gray grabbed before landing on my bucket hat.

Photo used with written permission from Michael Powell.

I was happy to provide a white table cloth for a classy dining experience with one of my favorite species of dragonflies.

Habitat

For habitat-specific odonates such as T. thoreyi, it’s all about location, location, location. “Gray Petaltail dragonfly (male)” is another blog post by Walter Sanford that provides actionable intel regarding ideal habitat for Grays.

Range map

The following map shows all official records for Tachopteryx thoreyi in the United States of America. Gray Petaltail is a habitat specialist that is challenging to find.

Related Resources

  • Tachopteryx thoreyi Gray Petaltail on NatureServe Explorer. The conservation status for T. thoreyi in Virginia is “Apparently Secure (S4).” That’s good news. The bad news: That doesn’t mean it’s easy to find.
  • Gray Petaltail dragonfly (male)” – another blog post by Walter Sanford that provides actionable intel regarding ideal habitat for Grays.

Copyright © 2021 Walter Sanford. All rights reserved.

Bar-winged Skimmer dragonfly (male)

July 9, 2021

A Bar-winged Skimmer dragonfly (Libellula axilena) was spotted along the shoreline of a small pond at an undisclosed location in Prince William County, Virginia USA.

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

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

This mature male has mated many times, as indicated by the scratches on the light-blue pruinescence covering his abdomen.

Males that have mated often have marks on their abdomen where the female legs have scratched them. This is especially obvious in species in which males develop pruinosity, as the pruinosity on the mid-abdomen is scratched off, and the signs are visible at some distance. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 390-392). Princeton University Press. Kindle Edition.

The next photo is full-frame (4,000 x 3,000 pixels), that is, uncropped.

17 JUN 2021 | PNC. Wm. County |  Bar-winged Skimmer (mature male)

Look closely along the leading edge of this individual’s wings. Notice the dark bars from which the common name for this species is derived are almost invisible.

Habitat

According to Dr. Steve Roble’s excellent datasets for the Commonwealth of Virginia, the adult flight period for Bar-winged Skimmer is from May 08 to September 28. Dr. Roble describes its habitat as “ponds.”

“Ponds” is perhaps too simple a descriptor for the habitat preferred by Bar-winged Skimmer, otherwise L. axilena should be more common than a map of its range suggests. Dennis Paulson provides a little more specificity.

Habitat: Wooded slow streams and sloughs, forest pools. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 9152). Princeton University Press. Kindle Edition.

Kevin Munroe, former manager at Huntley Meadows Park, provides the best description of Bar-winged Skimmer habitat that I’ve seen.

One of our less common skimmers, this dragonfly has relatively specific habitat needs. It prefers very shallow marshy pools in the full sun. If there’s enough water for fish, it’s too deep for Bar-winged Skimmers. And of course shallow pools in the full sun tend to quickly evaporate and dry up, so stable populations in Northern Va. are few and far between. The similar Great Blue Skimmer also likes shallow water, but is much more common. One reason being that they can handle partly shady forest pools and forest swamps, both too dark for Bar-wings. Source Credit: Bar-winged Skimmer, by Kevin Munroe.

I have observed Bar-winged Skimmer dragonflies at two locations in Huntley Meadows Park that provided habitat similar to Kevin’s recipe. Bar-winged Skimmer is no longer found at either place.

I have seen Bar-winged Skimmer at Sundew Bog, located in the Central Tract at Patuxent Research Refuge.

The Central Tract of the refuge is closed to public visitation due to the sensitive nature of much of the scientific work. Source Credit: Patuxent Research Refuge brochure.

Range map

Not all species of Skimmers are as common as I tend to think. For example, the following map shows all official records for Libellula axilena in the United States of America. As you can see, Bar-winged Skimmer is a relatively uncommon species of odonate.

What are the take-aways?

Many species of dragonflies in the Family Libellulidae (Skimmers) are habitat generalists and relatively easy to find almost anywhere there is water. In contrast, I think it’s fair to say Bar-winged Skimmer is a habitat specialist that is challenging to find.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Common Sanddragon dragonflies (males)

July 2, 2021

Two Common Sanddragon dragonflies (Progomphus obscurus) were spotted along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

Both individuals are male, as indicated by their terminal appendages and “indented” hind wings.

Male No. 1

I spotted a Common Rockdragon while searching for Eastern Least Clubtail (Stylogomphus albistylus). OK, OK, there is no species of dragonfly called “Common Rockdragon.” My point is simply this: Common Sanddragon is typically found perching on sand rather than rocks. Any perch in a storm I guess.

17 JUN 2021 | PNC. Wm. County | Common Sanddragon (male)

Anyway, this guy was super skittish — I got one shot before he flew away. I waited a while for him to return. No luck. So I moved on.

Male No. 2

I stopped to rest at a sandy bank (located farther upstream from the first location)  where I have seen/photographed Common Sanddragon in the past. Sure enough, a male Common Sanddragon landed on the beach soon after I sat down on my camp stool.

The first photo is cropped for better composition.

17 JUN 2021 | PNC. Wm. County | Common Sanddragon (male)

He took flight several times but always returned to the same place. I speculate he was actively hunting insects flying over the stream.

The next two photos are full-frame (4,000 x 3,000 pixels), that is, uncropped.

17 JUN 2021 | PNC. Wm. County | Common Sanddragon (male)

The male’s “indented” hind wings (see “Related Resource”) are shown clearly in the full-size versions of these photos.

17 JUN 2021 | PNC. Wm. County | Common Sanddragon (male)

Related Resource

Ed Lam, author and illustrator of Damselflies of the Northeast, created the following composite image that shows how to differentiate male and female Common Sanddragons. Notice the difference in the shape of male and female hind wings: male hind wings are “indented” near the body; female hind wings are rounded.

Ed-Lam_Common-Sanddragon_male-female

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.

 


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