Posts Tagged ‘Carolina Saddlebags dragonfly’

Tramea carolina exuvia

December 12, 2016

An exuvia from an unknown species of dragonfly was collected on 04 October 2016 at Mason Neck West Park (MNWP), Fairfax County, Virginia USA. A two-step process was used to identify the genus and species of the specimen.

Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06).

The exuviae has a mask-like labium (not flat) with evenly-toothed crenulations, indicating this individual is a member of Family Libellulidae (Skimmers). [See Photo No. 2.]

Genus and species

A dichotomous key was used to tentatively identify the exuvia as Carolina Saddlebags dragonfly (Tramea carolina), as indicated by the following morphological characteristics.

  • No dorsal hooks on any abdominal segments.
  • Lateral spines of abdominal segment nine (S9) are much longer than its mid-dorsal length. Lateral spines on segment eight (S8) are nearly as long as on segment nine (S9).[See Photo No. 3.]
  • Superior abdominal appendage (epiproct) is shorter than inferior abdominal appendages (paraprocts). [See Photo No. 3.]

Sincere thanks to Sue Gregoire, Kestrel Haven Migration Observatory, for verifying my preliminary observations and tentative identification!

No. 1

The specimen is approximately 2.4 cm (~0.9″) in length. Notice there are no dorsal hooks on any abdominal segments.

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 1 | Carolina Saddlebags (Tramea carolina) | exuvia (dorso-lateral)

The white filaments that extend from the split in the thorax (as shown in Photo No. 1-2, 4-6) are breathing tubes, artifacts of the unique respiratory system of dragonfly nymphs.

No. 2

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

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 2 | Carolina Saddlebags (Tramea carolina) | exuvia (face-head)

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

No. 3

A vertical white line marks the mid-dorsal length of abdominal segment nine (S9), as shown in the following annotated image; the vertical black line labeled “mid-dorsal length” is the same length as the white line. Notice the lateral spines of abdominal segment nine (S9) are much longer than its mid-dorsal length.

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 3 | Carolina Saddlebags (Tramea carolina) | exuvia (anal pyramid)

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

One of the keys to identifying skimmer dragonflies to the species level is to carefully examine the anal pyramid (S10), including the cerci (sing. cercus), epiproct, and paraprocts. Notice the epiproct is shorter than the paraprocts.

There is a lot of “seaweed” (aquatic vegetation) clinging to the exuvia, especially noticeable at the posterior end. Some collectors like to clean their specimens; I prefer to photograph them “as is.”

More photos of the exuvia are shown below.

No. 4

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 4 | Carolina Saddlebags (Tramea carolina) | exuvia (dorsal)

No. 5

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 5 | Carolina Saddlebags (Tramea carolina) | exuvia (face-head)

No. 6

A dragonfly exuvia (Tramea carolina) collected at Mason Neck West Park, Fairfax County, Virginia USA.

No. 6 | Carolina Saddlebags (Tramea carolina) | exuvia (anal pyramid)

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 genus of the dragonfly exuviae is as follows: 1b; 4b; 5b; 10a; 11b; 12b Tramea. A supplemental key featuring one dichotomy was used to identify the species: 1a carolina BINGO!

In long form, the decision tree is as follows:

p. 36, Key to the Genera of the Family Libellulidae
1b – Eyes lower, more broadly rounded and more lateral in position; abdomen usually ending more bluntly. [Go to] 4
4b – These appendages [inferior abdominal appendages (paraprocts)] straight or nearly so. [Go to] 5
5b – No dorsal hooks on any abdominal segments. [Go to] 10
10a – Lateral spines of segment 9 much longer than its mid-dorsal length. [Go to] 11
11b – Lateral spines on 8 nearly as long as on 9. [Go to] 12
12b – Superior abdominal appendage (epiproct) shorter than inferiors [inferior abdominal appendages (paraprocts)]. Tramea BINGO!

p. 41, Key to the species of the genus Tramea
1a – Lateral spines of segment 8 directed straight to rearward; paraprocts longer than epiproct; two rows of spinules on upper surface of epiproct. carolina BINGO!

Tech Tips

The following equipment was used to shoot the preceding photographs:

Adobe Photoshop CC 2017 was used to annotate selected images.

Copyright © 2016 Walter Sanford. All rights reserved.

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Carolina Saddlebags dragonflies (males)

July 8, 2016

Let’s play a quick game of word association. What’s the first color you think of when I say “Carolina?” If you’re like me, then you’re thinking “Carolina blue.” And so I was puzzled by the origin of “Carolina Saddlebags,” the common name for Tramea carolina — a remarkably red dragonfly. I consulted the experts of the Southeastern Odes Facebook group.

It was probably first known from [the work of English naturalist Mark Catesby in] Charleston, the source of many specimens that made their way across the Atlantic to European taxonomists, so I suppose we should have named it South Carolina Saddlebags. Source Credit: Dennis Paulson, author of Dragonflies and Damselflies of the East (Princeton Field Guides).

Hidden Pond, Meadowood Recreation Area

I spotted a single Carolina Saddlebags dragonfly perching near the edge of Hidden Pond at Meadowood Recreation Area.

A Carolina Saddlebags dragonfly (Tramea carolina) spotted at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male.

02 JUL 2016 | MRA | Carolina Saddlebags (male)

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

A Carolina Saddlebags dragonfly (Tramea carolina) spotted at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male.

02 JUL 2016 | MRA | Carolina Saddlebags (male)

Carolina Saddlebags dragonfly looks similar to Red Saddlebags dragonfly (Tramea onusta). One way to differentiate the two species is to look closely at the red “saddlebags” on their hind wings.

A Carolina Saddlebags dragonfly (Tramea carolina) spotted at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a male.

02 JUL 2016 | MRA | Carolina Saddlebags (male)

Mason Neck West Park

The next photo — showing a male Carolina Saddlebags in flight over a small water retention pond at Mason Neck West Park (MNWP) — features a better view of the red saddlebags.

A Carolina Saddlebags dragonfly (Tramea carolina) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male, shown in flight.

02 JUL 2016 | MNWP | Carolina Saddlebags (male, in flight)

The following composite image — created by Ed Lam, author and illustrator of Damselflies of the Northeast — clearly shows the difference in the shape of the saddlebags for Carolina- versus Red Saddlebags. Look closely at the saddlebags in the full-size version of the preceding photo and you can see the pattern perfectly matches the Carolina Saddlebags in Ed’s image, shown below.

Carolina-and-Red-Saddlebags

Composite image used with permission from Ed Lam.

Dragonflies are classified as either “fliers” or “perchers,” based upon their feeding habits. Carolina Saddlebags dragonflies are fliers; it is more common to see them flying than perching. I saw several Carolina Saddlebags at Mason Neck West Park, including both males and females, but I never saw one land during several hours of observation. Based upon this experience, the male I spotted perching at Hidden Pond (shown above) was an unexpected surprise!

A Carolina Saddlebags dragonfly (Tramea carolina) spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a male, shown in flight.

02 JUL 2016 | MNWP | Carolina Saddlebags (male, in flight)

Copyright © 2016 Walter Sanford. All rights reserved.


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