Posts Tagged ‘teneral’

Seamless transition

May 27, 2018

A seamless transition from the spring species of odonates to the summer species is slowly but surely underway.

Spangled Skimmer (Libellula cyanea) is a summer species that starts to appear in Northern Virginia in late spring. The following individual — spotted at Hidden Pond during a photowalk at Meadowood Recreation Area (MRA), Fairfax County, Virginia USA — is a teneral female, as indicated by her tenuous wings and terminal appendages.

21 MAY 2018 | MRA | Spangled Skimmer (teneral female)

Female Spangled Skimmers have a pair of flanges beneath their eighth abdominal segment that are used to scoop and hold a few drops of water when laying eggs (oviposition), hence the family name “Skimmer.” Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

Copyright © 2018 Walter Sanford. All rights reserved.

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Blue Corporal (teneral males)

May 3, 2018

Several teneral male Blue Corporal dragonflies (Ladona deplanata) were spotted near Painted Turtle Pond during a photowalk at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Teneral/immature/young male Blue Corporals look similar to females of the same species. Terminal appendages can be used to differentiate gender: males have three (3) appendages; females have two (2).

Some of the ground cover is charred from a recent controlled burn at Occoquan Bay NWR.

The common name for Blue Corporal is derived from two cream-colored stripes that appear on the front of the thorax, similar to the two stripes that signify the rank of corporal in the military. As a mature male, those stripes will be partially obscured by dark blue pruinescence.

Related Resource: Blue Corporal (teneral females).

Copyright © 2018 Walter Sanford. All rights reserved.

Blue Corporal (teneral females)

May 1, 2018

Lots of Blue Corporal dragonflies (Ladona deplanata) were spotted near Painted Turtle Pond at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This is the first time the author has observed Blue Corporal at Painted Turtle Pond.

Both individuals featured in this post are teneral females, as indicated by their tenuous wings and terminal appendages.

Female 1

The first female was spotted perching on vegetation near the shoreline of Painted Turtle Pond. Some of the ground cover is charred from a recent controlled burn at Occoquan Bay NWR.

The common name for Blue Corporal is derived from two cream-colored stripes that appear on the front of the thorax, similar to the two stripes that signify the rank of corporal in the military.

Notice the abdomen of this female seems to be bent slightly to the right (facing forward). This malformation probably occurred during emergence.

Female 2

The last female was spotted perching on the gravel road leading to Painted Turtle Pond. The purple rock located in the upper-right corner of the photo might contain the mineral fluorite.

Like many teneral dragonflies, if not most, this individual was quite skittish. I followed the female to two locations before calling the photowalk a wrap.

Related Resource: Blue Corporal (teneral males).

Copyright © 2018 Walter Sanford. All rights reserved.

Common Baskettail (teneral female)

April 29, 2018

A Common Baskettail dragonfly (Epitheca cynosura) was spotted near Painted Turtle Pond during a photowalk at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

This individual is a teneral female, as indicated by her tenuous wings and relatively short, straight terminal appendages.

Spring 2018 has been slow to spring in the mid-Atlantic USA, as evidenced by the fact that the first Common Baskettails were spotted at Painted Turtle Pond beginning in mid-April 2017.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

New discoveries in 2017 (odonates)

December 28, 2017

There’s always more to discover/learn! My odonate-related new discoveries in 2017 are presented in reverse-chronological order.

Fine-lined Emerald dragonfly

A Fine-lined Emerald dragonfly (Somatochlora filosa) was spotted at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is one of several males spotted during a period of a week-or-so in mid-September 2017.

Immature male Calico Pennant

20 JUN 2017 | OBNWR | Calico Pennant (immature male)

A Calico Pennant dragonfly (Celithemis elisa) was spotted at Painted Turtle Pond, Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is an immature male. Notice its coloration is similar to female Calico Pennants.

Allegheny River Cruiser dragonfly

An Allegheny River Cruiser (Macromia alleghaniensis) was netted by Mike Blust at Hardware River Wildlife Management Area, Fluvanna County, Virginia USA. This individual is a male.

Harpoon Clubtail dragonfly

09 JUN 2017 | Highland County, VA | Harpoon Clubtail (male)

A Harpoon Clubtail dragonfly (Phanogomphus descriptus) was spotted at “Straight Fork,” Highland County, Virginia USA. This individual is a male. Sincere thanks to fellow Virginians Karen Kearney and Mike Boatwright for guiding me to this unique high-elevation habitat.

It’s worth noting that I saw two more new species during the same trip: Riffle Snaketail (Ophiogomphus carolus); and Dot-tailed Whiteface (Leucorrhinia intacta).

Those who know me well are familiar with one of many “Walterisms”: “I haven’t ‘seen’ something until I have photographed it.” My rationale is two-fold: 1) A photograph verifies a sighting. 2) The detail visible in a good photograph exceeds the acuity of the human eye. Suffice it to say I saw two other species but haven’t seen them. Makes sense to me!

Swift River Cruiser dragonfly

A Swift River Cruiser dragonfly (Macromia illinoiensis) was spotted at Riverbend Park, Fairfax County, Virginia USA. This individual is an emergent/teneral female.

Spine-crowned Clubtail dragonfly

A Spine-crowned Clubtail dragonfly (Hylogomphus abbreviatus) spotted along Bull Run at Hemlock Overlook Regional Park, Fairfax County, Virginia USA. This individual is a male. A female was spotted on the same day at a nearby location.

Epitheca cynosura exuvia

A Common Baskettail dragonfly (Epitheca cynosura) exuvia was collected at Painted Turtle Pond, Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Epitheca princeps exuvia

05 MAR 2017 | Prince Baskettail (Epitheca princeps) | exuvia (face-head)

A Prince Baskettail dragonfly (Epitheca princeps) exuvia was collected from an unknown location. This specimen was on temporary loan from Huntley Meadows Park, Fairfax County, Virginia USA.

Copyright © 2017 Walter Sanford. All rights reserved.

The ugly side of Mother Nature

October 1, 2017

A Big Bluet damselfly (Enallagma durum) was spotted during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is a male, eating a teneral damselfly.

10 SEP 2017 | Occoquan Bay NWR | Big Bluet (male, eating prey)

I think they may both be Big Bluets. Source Credit: Michael Moore, Virginia Odonata Facebook group.

Some species of odonates are cannibals, that is, they feed on their own species. And there it is — the ugly side of Mother Nature!

Copyright © 2017 Walter Sanford. All rights reserved.

Pop quiz answer key

June 9, 2017

Perhaps the simplest way to provide answers to the recent pop quiz — in which readers were challenged to identify the gender of two Southern Spreadwing damselflies (Lestes australis) — is to show what the teneral/immature male (shown in my last post) will look like when he’s a little older.

The following photos show Southern Spreadwings spotted at Mason Neck West Park, Fairfax County, Virginia USA. Both individuals are male, as indicated by their terminal appendages and blue coloration.

Both photographs of the male Southern Spreadwings were taken at an angle that shows their terminal appendages clearly.

All male damselflies have four terminal appendages, collectively called “claspers.” Male damselfly terminal appendages don’t look exactly the same for all species of damselflies, but their function is identical. Claspers are used to grab and hold female damselflies during mating: an upper pair of cerci (“superior appendages”) and a lower pair of paraprocts (“inferior appendages”).

In contrast, female damselflies have two cerci (sing. cercus), superior appendages that have little or no function. Notice the two “nubs” at the tip of the abdomen, as shown in the photo of the female Southern Spreadwing that was featured in the pop quiz.

Editor’s Notes: There are five families of damselflies (Suborder Zygoptera) in the United States of America, although only three families occur in the mid-Atlantic region: Family Calopterygidae (Broad-winged Damselflies)Family Coenagrionidae (Narrow-winged Damselflies); and Family Lestidae (Spreadwings).

Male Broad-winged Damselflies and Spreadwing Damselflies have terminal appendages that are large enough to see with the unaided eye. Generally speaking, both male and female Narrow-winged Damselflies are too small to see their terminal appendages clearly in most photographs.

Copyright © 2017 Walter Sanford. All rights reserved.

Pop quiz

June 7, 2017

OK, it’s time to assess what you’ve learned about damselflies by following my blog.

Two Southern Spreadwing damselflies (Lestes australis) were photographed on the same day at the same location. Both damselflies are teneral/immature, that is, they are relatively young. One is a female; one is a male. Can you identify the gender of the damselflies shown in the following photos?

I’ll give you a hint: Examine their terminal appendages by looking at the full-size version of both photos.

No. 1

No. 2

Editor’s Note: The answer key will be published in my next post.

Copyright © 2017 Walter Sanford. All rights reserved.

Swift River Cruiser (emergent female)

May 30, 2017

A Swift River Cruiser dragonfly (Macromia illinoiensis) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a late-stage emergent teneral female, as indicated by her terminal appendages.

Many of the major milestones during the miraculous process of emergence occurred before I spotted the dragonfly. I photographed the process from the first sighting to the time when I had to stop (see The Backstory, below): I shot 102 photos in approximately one hour; time is compressed by showcasing five (5) select photos from the first-to-last sighting.

The following photo is the first image from a time-series documenting the late-stage 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 01:01:15 is the total elapsed time.

27 MAY 2017 | 09:09:13 am EDT | Elapsed time: 00:00:00

The wings seem to be fully expanded (as shown in the preceding photo), evidenced by the fact that it appears some of the greenish hemolymph has been pumped out of the wings and into the abdomen.

27 MAY 2017 | 09:51:08 am EDT | Elapsed time: 00:41:55

Notice the wings are mostly clear in the following photo, in contrast with the first photo in this gallery. Next the abdomen expanded slowly until it was longer than the wings, as shown in the last photo.

27 MAY 2017 | 09:52:33 am EDT | Elapsed time: 00:43:20

As time passed, more of the adult coloration began to appear. Notice the large yellow spot on the dorsal side of abdominal segment seven (S7).

27 MAY 2017 | 09:57:39 am EDT | Elapsed time: 00:48:26

The last photo shows the dragonfly waiting for the wings and body to harden before its first flight.

27 MAY 2017 | 10:10:28 am EDT | Elapsed time: 01:01:15

The Backstory

I woke up at 4:30 a.m. in order to be at Riverbend Park when the gates open at 7 a.m. I had to attend a training session in order to be a volunteer collector of dragonfly exuviae for a research program sponsored by the park. The class started at 10 a.m., but I wanted to look around and shoot photos before the class.

I found almost nothing photo-worthy until soon after 9:00 a.m. when I spotted the emergent Swift River Cruiser dragonfly. The emergence was well underway at that point; I had to go to class before the wings spread and the teneral dragonfly flew away.

The emergence site was in a high-traffic location, so the daughter of a woman in the class guarded/watched the teneral until it flew away safely. After class, I collected the exuvia. I will shoot a set of studio macro photographs of the exuvia before returning the specimen to the park.

Swift River Cruiser is a new species of dragonfly for my life list.

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.


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