Posts Tagged ‘Epitheca cynosura’

Common Baskettail (terminal appendages)

May 18, 2017

A male and female Common Baskettail dragonfly (Epitheca cynosura) were spotted recently at the same location in Fairfax County, Virginia USA.

Male and female Common Baskettails look similar. Terminal appendages can be used to identify gender.

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”).

03 MAY 2017 | Fairfax County, VA | Common Baskettail (male)

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

Female

Female dragonflies have a pair of cerci (superior appendages) that have little or no function. The abdomen of female Common Baskettails is noticeably thicker than males of the same species.

03 MAY 2017 | Fairfax County, VA | Common Baskettail (female)

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

A better view of the subgenital plate is provided by the following digital scan of the underside of the abdomen of a female Common Baskettail. The subgenital plate looks a little like a pair of calipers. Also known as vulvar lamina, the subgenital plate is located under the ninth abdominal segment (S9) of some female odonates and “serves to hold eggs in place during exophytic oviposition.” Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

Image used with permission from Ed Lam.

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.

Non-stop flight

April 22, 2017

On 18 April 2017, a Common Baskettail dragonfly (Epitheca cynosura) was spotted patrolling part of the shoreline at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male, in flight.

108mm (600mm equivalent) | ISO 100 | f/5.2 | 1/800s | -1 ev | flash fired

The photograph was taken using a Panasonic LUMIX DMC-FZ150 superzoom bridge camera and a Canon 580EX Speedlite external flash set for manual mode at 1/8 power and 105mm zoom.

Related Resource: Stop-action photography of dragonflies in flight, a blog post by Walter Sanford, features Phil Wherry’s answer to my question “How fast would the camera shutter speed need to be in order to freeze all motion of a dragonfly in flight?”

Copyright © 2017 Walter Sanford. All rights reserved.

Late-stage emergent baskettail dragonfly

April 18, 2017

Common Baskettail dragonfly (Epitheca cynosura) was spotted at Painted Turtle Pond during a photowalk around Occoquan Bay National Wildlife Refuge (OBNWR), Prince William County, Virginia USA. This individual is a late-stage emergent teneral female.

I photographed the process of emergence from the first sighting to the time when the teneral dragonfly flew away: I shot 23 photos in approximately 16 minutes; time is compressed by showcasing six (6) select photos taken at major milestones during the event.

The following photo is the first image from a time-series documenting the emergence of the teneral female. Elapsed time is expressed in hh:mm:ss format, e.g., 00:00:00 is the time when I spotted the emergent teneral female, and 00:16:08 is the total elapsed time.

13 APR 2016 | 11:38:41 am EDT | Elapsed time: 00:00:00

Notice the drop of fluid at the tip of the abdomen. Emerging dragonflies pump fluid into their wings, causing the wings to expand. Next, the same fluid is withdrawn from the wings and used to expand the abdomen. Excess fluid is expelled afterward.

13 APR 2016 | 11:40:48 am EDT | Elapsed time: 00:02:07

The next photo shows the first time the wings opened.

13 APR 2016 | 11:48:55 am EDT | Elapsed time: 00:10:14

Then the wings closed again and remained closed for a while.

13 APR 2016 | 11:51:02 am EDT | Elapsed time: 00:12:21

The wings reopened a few minutes later. Notice that several wings are malformed slightly.

13 APR 2016 | 11:54:14 am EDT | Elapsed time: 00:15:33

Finally, the wings open up, and very soon the teneral adult flies away. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 468). Princeton University Press. Kindle Edition.

The teneral female dragonfly flew away immediately after the last photo in the time-series.

13 APR 2016 | 11:54:46 am EDT | Elapsed time: 00:16:08

This individual is a female, as indicated by her cerci (superior appendages) and thick abdomen. Common Baskettail females have shorter cerci and a thicker abdomen than males of the same species.

Exuviae (in situ)

Several dragonfly exuviae were spotted at Painted Turtle Pond. The exuviae were identified using a dichotomous key for dragonfly larvae; they are cast skins from Common Baskettail.

13 APR 2017 | OBNWR | Common Baskettail (exuvia)

These exuviae are not the one from which the teneral female featured in this post emerged.

13 APR 2017 | OBNWR | Common Baskettail (exuvia)

Copyright © 2017 Walter Sanford. All rights reserved.

Common Baskettail dragonfly (male)

April 16, 2017

A Common Baskettail dragonfly (Epitheca cynosura) was spotted near Painted Turtle Pond during a photowalk at Occoquan Bay National Wildlife Refuge (OBNWR). Common Baskettail is a member of Family Corduliidae (Emeralds); this species is seen during early spring in mid-Atlantic United States like Virginia.

I thought this might be a Slender Baskettail dragonfly (Epitheca costalis) due to narrowing of its abdomen. Turns out that was wishful thinking.

13 APR 2017 | OBNWR | Common Baskettail (male)

This individual is a male, as indicated by his terminal appendages. The curved shape of the cerci (superior appendages) is a key field marker for Common Baskettail; in contrast, the cerci for Slender Baskettail tend to be more parallel. Thanks to Mike Boatwright and Paul Guris, members of the Northeast Odonata Facebook group, for reminding me of this pearl of wisdom!

I think baskettail cerci look “rubberized,” like the handles of metal tools made for working with electricity. Whenever I see this distinctive field marker, shown clearly in the following photos, I know the dragonfly is probably a species of baskettail.

13 APR 2017 | OBNWR | Common Baskettail (male)

The last photo shows a dorso-lateral view of the male dragonfly. Notice the epiproct (inferior appendage) is visible clearly in this photo.

13 APR 2017 | OBNWR | Common Baskettail (male)

Also notice the light-colored spots on the hairs covering the body of the dragonfly. The following article by John Abbott suggests the spots may be some type of pollen.

Related Resource: Identification of Male Epitheca (Tetragoneuria) in Texas, by John C. Abbott.

Copyright © 2017 Walter Sanford. All rights reserved.

Common Baskettail dragonfly (female)

July 12, 2016

A Common Baskettail dragonfly (Epitheca cynosura) was spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge. This individual is a female, as indicated by her rounded hind wings and simple, straight terminal appendages.

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female.

26 JUN 2016 | JMAWR | Common Baskettail (female)

The shoreline of Mulligan Pond was patrolled actively by male Common Baskettail dragonflies during late-May 2016. It’s worth noting that no male Common Baskettails were spotted during my photowalk around the pond approximately one month later.

Copyright © 2016 Walter Sanford. All rights reserved.

Uncommonly cooperative Common Baskettail

May 31, 2016

Common Baskettail (Epitheca cynosura) was spotted on 24 May 2016 during a photowalk around Mulligan Pond at Jackson Miles Abbott Wetland Refuge.

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

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

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

Some segments of the lake shoreline were patrolled by a single male Common Baskettail dragonfly, like the one featured in this photo set. Common Baskettails are fliers rather than perchers. I noticed this individual would fly back-and-forth for 10s of minutes, then pause to perch for a while — never longer than a minute-or-so.

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

I staked out a position near the center of the male’s patrol route and waited for him to land. Although he never landed in the same spot, all of the perches were confined to a relatively small area.

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

My front-row seat had an obstructed view for the last shot. Soon afterward, the dragonfly simply disappeared. But hey, it was a good show while it lasted!

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

Copyright © 2016 Walter Sanford. All rights reserved.

Common Baskettail dragonfly (male, in flight)

May 17, 2016

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Enchanted Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male, in flight.

Common Baskettail (Epitheca cynosura) was spotted on 14 May 2016 at Enchanted Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male, as indicated by its terminal appendages. Notice the male’s bright blue-green eyes in the preceding photo. It’s easy to see why Common Baskettail is a member of the Emerald Family of dragonflies!

Enchanted Pond is relatively small. The shoreline seemed to be subdivided into imaginary segments of valuable real estate; each segment was patrolled by a single male Common Baskettail dragonfly. There were frequent aerial skirmishes when one male strayed into the territory of another. During nearly an hour of observation, I never saw one of the males land. Talk about stamina!

Copyright © 2016 Walter Sanford. All rights reserved.

Common Baskettail dragonfly (male)

April 25, 2016

Common Baskettail (Epitheca cynosura) is a member of the Emerald Family of dragonflies that is seen during early spring in mid-Atlantic United States like Virginia.

The following annotated image shows a male Common Baskettail dragonfly spotted on 20 April 2016 at Accotink Bay Wildlife Refuge. 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”).

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Accotink Bay Wildlife Refuge, Fairfax County, Virginia USA. This individual is a male.

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

I think baskettail cerci look “rubberized,” like the handles of metal tools made for working with electricity. Whenever I see this distinctive field marker, I know the dragonfly is probably a species of baskettail.

Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.

  • Genus Epitheca | Epitheca cynosura | Common Baskettail | male | top view
  • Genus Epitheca | Epitheca cynosura | Common Baskettail | male | side view

See also What was your first clue? – a tutorial illustrating female Common Baskettail reproductive anatomy.

Copyright © 2016 Walter Sanford. All rights reserved.

What was your first clue?

April 27, 2015

I have photographed relatively few members of the Emerald Family of dragonflies. After tentatively identifying the following individual as a female Common Baskettail (Epitheca cynosura), I consulted the experts of the Northeast Odonata Facebook group for verification: I was fairly certain of the species; less certain of the gender.

Experienced odonate hunters like Chris Hill and Ed Lam looked at the specimen and quickly recognized its gender, as indicated by the cerci (terminal appendages) and thickness of its abdomen. In contrast, I haven’t seen enough baskettails to feel comfortable using those field markers to identify the gender.

So you may be wondering, “What was your first clue this individual is a female?” In a word (well, two) its subgenital plate, as shown in the following annotated image.

A Common Baskettail dragonfly (Epitheca cynosura) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

24 APR 2015 | Huntley Meadows Park | Common Baskettail (female)

A better view of the subgenital plate is provided by the following digital scan of the underside of the abdomen of a female Common Baskettail. The subgenital plate looks a little like a pair of calipers. Also known as vulvar lamina, the subgenital plate is located under the ninth abdominal segment (S9) of some female odonates and “serves to hold eggs in place during exophytic oviposition.” Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

11161355_10206237290082057_635765194893154908_n

Image used with permission from Ed Lam.

Related Resource: Common Baskettail dragonfly (male) – a tutorial illustrating male reproductive anatomy.

Editor’s Note: Special thanks to Chris Hill and Ed Lam, members of the Northeast Odonata Facebook group, for kindly confirming my tentative identification of the gender of this specimen and for teaching me about the subgenital plate (a.k.a., vulvar lamina) — a feature that I misidentified as an “ovipositor” in my initial post to the group.

Copyright © 2015 Walter Sanford. All rights reserved.


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