Uhler’s Sundragon dragonfly (emergent female)

Uhler’s Sundragon (Helocordulia uhleri) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

The dragonfly was perched on the exuvia from which it emerged; its cast skin was still clinging to a grass stem approximately six inches (6″) above the ground. The patch of grass was located two-to-three feet from the shoreline, where the stream current was slow-to-moderate. The stream bed was sandy and gently sloped near the site on land where the dragonfly larva stopped to eclose.

This individual is an emergent female, as indicated by her teneral appearance, rounded hind wings, terminal appendages, and subgenital plate.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (emergent female)

The subgenital plate is located on the ventral side of the abdomen beneath segment eight.

Underneath Segment 8 there is either an ovipositor or a subgenital plate, depending upon the species [of dragonfly]. Both structures are for laying eggs and extend over Segment 9 and possibly beyond. Source Credit: Dragonflies of the North Woods, by Kurt Mead.

Remember that “Segment 8 and 9” refers to abdominal segments eight and nine (of 10), numbered from front to back.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (emergent female)

The following graphic from Dragonflies and Damselflies of the East by Dennis Paulson shows the shape of the subgenital plate on our emergent female matches Uhler’s perfectly.

Graphic used with written permission from Dennis Paulson.

True Detective

Generally speaking, teneral odonates are more challenging to identify than most mature adult dragonflies and damselflies. Full disclosure: Neither Mike nor I were certain of the identity of the emergent female when we were shooting photographs in the field. “Shoot first and ask questions later” is one of my mantras for wildlife photography.

The most reliable way to identify odonate larvae to the species level is to rear them to maturity and emergence, that is, unless you’re fortunate to find a larva emerging in the field. Since an exuvia is essentially a nearly perfect shell of the last instar, it can be used to identify other specimens of the same species by pattern matching.

In this case, I used the exuvia to reverse-engineer the identity of the teneral dragonfly. Look closely at a lateral view of the exuvia, as shown in the following photo taken by Mike Powell. Notice there are dorsal hooks on abdominal segments seven, eight, and nine (S7-9). This distinctive field mark confirms the identity of the species as H. uhleri.

Photo used with written permission from Michael Powell.

Also notice Mike’s photo shows a clear view of the emergent female’s terminal appendages, as well as the subgenital plate on the underside of her abdomen.

How it all began, and ended.

The sky was almost completely overcast and it was cool and windy when I spotted the emergent female. Mike Powell and I observed the dragonfly for quite a while and there was little noticeable progress. According to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, the process of emergence can take longer when the air temperature is cooler.

When the sky began clearing, Mike Powell and I decided to go to a nearby place where he had seen adult Uhler’s recently. Later the same day, we returned to the site of the emergent female; she was gone, so I collected the exuvia. I plan to publish a photo set of the exuvia in an upcoming blog post. To be continued.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Tags: , , , , , , , ,

One Response to “Uhler’s Sundragon dragonfly (emergent female)”

  1. Emerging dragonfly | Mike Powell Says:

    […] Walter do it? For the answer to that mystery, check out Walter’s blog posting today called Uhler’s Sundragon dragonfly (emergent female) for the fascinating story of his detective work and additional photos and details of our encounter […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: