Posts Tagged ‘styli’

Left on the cutting room floor

April 15, 2019

Close readers of my blog may have noticed I’ve posted a lot of photos recently that were taken years ago. Why were the photos passed over for publication closer to the time the shots were taken?

Sometimes there are better shots from the same photowalk that I’m eager to share, and sometimes they just don’t make the grade. The former requires no explanation; the following photos help to illustrate the latter.

The following female Slender Spreadwing damselfly (Lestes rectangularis) was spotted during a photowalk around a vernal pool in the forest at Huntley Meadows Park. The damselfly was perched in a hidey-hole in the vegetation at angle that made it impossible to get the entire subject in focus from head-to-tail.

The first photo shows the head and thorax in focus, but the tip of the abdomen and terminal appendages are out of focus.

15 SEP 2016 | HMP | Slender Spreadwing (female)

The last photo shows the tip of the abdomen and terminal appendages in focus, but the head and thorax are in soft focus. Look closely at a full-size version of the photo and you can see both styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

15 SEP 2016 | HMP | Slender Spreadwing (female)

The odd thing is the focus point is nearly the same in both photos, and the aperture is identical. Go figure! Anyway, less than ideal focus is something that will cause me to reject photos every time. And then there’s that “too hot” blade of grass in the lower-right corner — talk about distracting!

Copyright © 2019 Walter Sanford. All rights reserved.

Great Spreadwing (practice oviposition)

October 15, 2017

This gallery — named “practice oviposition” (egg-laying) — features a six-photo time series of a female Great Spreadwing damselfly (Archilestes grandis).

Female Great Spreadwing damselflies, like all female odonates, have two cerci (sing. cercus), superior appendages that have little or no function. Also notice two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

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

The female uses her styli to guide the ovipositor into position, as shown in the next two photos.

In this case, I saw no evidence that the ovipositor actually penetrated the tree twig. I think this was a practice run in preparation for the real thing, as the title of this blog post says.

Copyright © 2017 Walter Sanford. All rights reserved.

Great Spreadwing damselfly (female)

October 13, 2017

A Great Spreadwing damselfly (Archilestes grandis) was spotted near a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA.

This individual is a female, as indicated by her terminal appendages and external reproductive anatomy, including two styli and an ovipositor.

Sometimes I struggle to choose between two similar images, so I decided to post both photos.

The following photo captured the “feel” of the morning light especially well.

The next two photos are among my favorites in this set.

This female was a more cooperative model after she moved to a perch on a man-made brush pile that provides habitat and shelter for many types of animals.

Female Great Spreadwing damselflies, like all female odonates, have two cerci (sing. cercus), superior appendages that have little or no function. Also notice two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

My next blog post will feature a six-photo time series that I named “practice oviposition” (egg-laying).

Copyright © 2017 Walter Sanford. All rights reserved.

Great Spreadwing (female terminal appendages)

November 9, 2016

Fall 2016 hadn’t been good for finding Great Spreadwing damselflies (Archilestes grandis) at Huntley Meadows Park. A formerly fishless vernal pool in a remote location at the park was less than productive, yielding only two males as a result of intense searches during September and October. Given this context, imagine my surprise and delight when several Great Spreadwings were spotted on a mild day in early November, including my first sighting of a single female!

The following photo shows a male Great Spreadwing damselfly spotted on the same day and near the same location as the female. Notice its deep blue eyes, familiar yellow racing stripe on the side of its thorax, bluish-white coloration on abdominal segments 9-10 (S9-10), and distinctive terminal appendages (claspers).

Although female Great Spreadwings feature the same yellow thoracic stripe as males, several other field markers are different. Female eyes are paler blue and two-toned. Females have a noticeably thicker abdomen, minus the male coloration on S9-10. And of course, female terminal appendages are different from male appendages.

A Great Spreadwing damselfly (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

06 NOV 2016 | Huntley Meadows Park | Great Spreadwing (female)

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

Female Great Spreadwing damselflies, like all female odonates, have two cerci (sing. cercus), superior appendages that have little or no function. Also notice two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

A Great Spreadwing damselfly (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

06 NOV 2016 | Huntley Meadows Park | Great Spreadwing (female)

All three photos of the female are full-frame, that is, uncropped; the photo of the male was cropped slightly, only because I’m almost as obsessed with the way the edges of a photo look as the subject of the photo! Although I’m not opposed to cropping photos for better composition, I prefer to get it right in-camera.

A Great Spreadwing damselfly (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

06 NOV 2016 | Huntley Meadows Park | Great Spreadwing (female)

Related Resources:

Editor’s Note: If you check the EXIF for all four photos, then you will see the time stamp is one hour later than the times shown above. 06 November was the first time I used my camera since the end of Daylight Saving Time (at 2:00 a.m. the same day) — I forgot to reset the time in-camera!

Copyright © 2016 Walter Sanford. All rights reserved.

Shadow Darner dragonfly (female)

October 18, 2016

A Shadow Darner dragonfly (Aeshna umbrosa) was spotted during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR).

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph.

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

This individual is a mature female, as indicated by her coloration, rounded hindwings (near abdomen), and terminal appendages. Female Shadow Darners are polymorphic; this one is a female heteromorph, as indicated by her brown eyes and duller coloration than males of the same species.

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph.

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

The following annotated image illustrates some parts of the reproductive anatomy of a female Shadow Darner dragonfly, including an ovipositor for egg-laying and two styli (sing. stylus), structures that serve as sensors in egg positioning.

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph. [Good view of ovipositor/styli.]

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

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

Both female and male Shadow Darners have two long, petal-like cerci (sing. cercus). Notice the female (shown above) is missing both cerci.

[Female] Cerci rounded at tip, longer than S9–10, usually broken off at maturitySource Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 4604). Princeton University Press. Kindle Edition.

In contrast, the following male has both cerci and an epiproct; the three terminal appendages are collectively called “claspers.” Claspers are used to grab and hold female damselflies during mating.

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

Related Resources: Scanned digital images from Western Odonata Scans in Life.

  • Shadow Darner | Aeshna umbrosaheteromorph female
  • Shadow Darner | Aeshna umbrosaheteromorph female (note very tattered wings of this old individual)
  • Shadow Darner | Aeshna umbrosaandromorph female
  • Shadow Darner | Aeshna umbrosamale (typical “A. u. umbrosa” with small green abdominal spots but nowhere near the range of that subspecies!)

Copyright © 2016 Walter Sanford. All rights reserved.

American Rubyspot damselflies

August 21, 2016

American Rubyspot (Hetaerina americana) is a member of the Family Calopterygidae (Broad-winged damselflies). They are common from May to October along rocky streams with riffles, such as the Potomac River at Riverbend Park.

Female

Female American Rubyspots are quite variable in appearance. The following specimen has a metallic green thorax and dark-colored abdomen; its wings feature a color gradient from red at the base to diffuse reddish-orange at the wing tips.

An American Rubyspot damselfly (Hetaerina americana) spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a female.

04 AUG 2016 | Riverbend Park | American Rubyspot (female)

The following annotated image illustrates some of the reproductive anatomy of a female American Rubyspot: two cerci (sing. cercus), superior appendages that have little or no function; and two styli (sing. stylus), structures that serve as sensors in egg positioning.

An American Rubyspot damselfly (Hetaerina americana) spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a female.

04 AUG 2016 | Riverbend Park | American Rubyspot (female)

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

Male

Male American Rubyspots have a metallic red thorax and dark-colored abdomen; its wings feature well-defined ruby-colored spots at the base. I was so focused on photographing the deep red wing spots that I forgot to shoot a dorsal view of the terminal appendages! No problem. See the digital scans under “Related Resources.”

An American Rubyspot damselfly (Hetaerina americana) spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a male.

08 AUG 2016 | Riverbend Park | American Rubyspot (male)

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

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”).

Related Resources:

Copyright © 2016 Walter Sanford. All rights reserved.

Great Spreadwing (mating pairs, in tandem)

October 30, 2015

Every year I set goals for odonate hunting. One goal for 2015: spot and photograph a female Great Spreadwing damselfly (Archilestes grandis). Although I never saw a solo female, I was fortunate to photograph several mating pairs at Huntley Meadows Park (HMP).

After copulation, Great Spreadwings engage in a form of guarding behavior known as “contact guarding,” in which the male and female fly “in tandem” to egg-laying sites. Contact guarding is used by some species of odonates to prevent aggressive males from hijacking the female.

A mating pair of Great Spreadwing damselflies (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem.

11 OCT 2015 | HMP | Great Spreadwing (mating pair, in tandem)

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

Look closely at the tip of the female’s abdomen. Notice several anatomical structures: two cerci (sing. cercus), superior appendages that have little or no function; two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition; and an ovipositor that is used to insert eggs into vegetation (endophytic oviposition).

A mating pair of Great Spreadwing damselflies (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem; the female is shown ovipositing.

21 OCT 2015 | HMP | Great Spreadwing (mating pair, in tandem)

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

The female is ovipositing in two similar-looking photos, shown above and below. Look closely at the full-size version of both photos: the preceding photo shows the ovipositor hasn’t penetrated the vegetation; the following photo shows the ovipositor has been inserted in the plant stem.

A mating pair of Great Spreadwing damselflies (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem; the female is shown ovipositing.

21 OCT 2015 | HMP | Great Spreadwing (mating pair, in tandem)

The male guided the female around-and-around a small vernal pool for at least 30 minutes, with brief stops for egg-laying at selected sites. The last photo shows the same mating pair taking a rest break. Notice the mud on the female’s wings and abdomen.

Ooooh, I need a dirty woman. Ooooh, I need a dirty girl. Source Credit: Young Lust, by Pink Floyd.

A mating pair of Great Spreadwing damselflies (Archilestes grandis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem.

21 OCT 2015 | HMP | Great Spreadwing (mating pair, in tandem)

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

Copyright © 2015 Walter Sanford. All rights reserved.

Slender Spreadwing damselfly (female)

October 14, 2015

The following gallery of photos features a Slender Spreadwing damselfly (Lestes rectangularis) spotted near a vernal pool at Huntley Meadows Park (HMP). This individual is a female, as indicated by its terminal appendages and the ovipositor located on the underside of the posterior abdomen. The ovipositor is used to insert eggs into vegetation (endophytic oviposition).

A Slender Spreadwing damselfly (Lestes rectangularis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

08 OCT 2015 | HMP | Slender Spreadwing (female)

See a full-size version of the preceding photo, without annotation.

A Slender Spreadwing damselfly (Lestes rectangularis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

08 OCT 2015 | HMP | Slender Spreadwing (female)

Look closely at the tip of the female’s abdomen. Notice a couple of anatomical structures: two cerci (sing. cercus), superior appendages that have little or no function; and two styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

A Slender Spreadwing damselfly (Lestes rectangularis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

08 OCT 2015 | HMP | Slender Spreadwing (female)

See a full-size version of the preceding photo, without annotation. Adobe Photoshop was used to remove a couple of small distracting elements from the photo.

The last two photos provide a good side view of the ovipositor.

A Slender Spreadwing damselfly (Lestes rectangularis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

08 OCT 2015 | HMP | Slender Spreadwing (female)

A Slender Spreadwing damselfly (Lestes rectangularis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

08 OCT 2015 | HMP | Slender Spreadwing (female)

Related Resource: Odonate Terminal Appendages.

Copyright © 2015 Walter Sanford. All rights reserved.

A Southern Fortnight, Part 6 – Damselfly reproductive anatomy

August 19, 2015

The Backstory: A Southern Fortnight

For the first two weeks during May 2015, Southern Spreadwing damselflies (Lestes australis) were observed at a vernal pool and nearby drainage ditch in the forest at Huntley Meadows Park. I spotted approximately six males and several females during the fortnight. Their sudden disappearance seemed to coincide with a population explosion of Eastern Pondhawk dragonflies (Erythemis simplicicollis) in mid-May. Eastern Pondhawks, especially females, are voracious predators with a penchant for preying upon damselflies.


The following annotated image illustrates some of the reproductive anatomy of male and female Southern Spreadwing damselflies.

A mating pair of Southern Spreadwing damselflies (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem; the female is laying eggs (oviposition).

08 MAY 2015 | HMP | Southern Spreadwing (mating pair, in tandem)

The following annotated image illustrates some of the reproductive anatomy of a female Southern Spreadwing: two cerci (sing. cercus), superior appendages that have little or no function; two styli (sing. stylus), structures that serve as sensors in egg positioning; and an ovipositor  (shown above) that is used to insert eggs into vegetation (endophytic oviposition).

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This is the female member of a mating pair, resting after laying eggs (oviposition).

07 MAY 2015 | HMP | Southern Spreadwing (adult female)

According to Ed Lam, author and illustrator of Damselflies of the Northeast, “male Southern and Sweetflag cannot be separated in the field.” It is possible to reverse-engineer a positive identification based upon a single key field marker for female specimens of the two species: Southern Spreadwing females have a much smaller ovipositor than Sweetflag Spreadwing females, as illustrated in the following references.

Sidebar: Damselfly Hook-up and Copulation

After a male damselfly grabs a female with his claspers, he transfers sperm from the genital opening under the ninth abdominal segment (S9) to his hamules, shown above, located beneath the second abdominal segment (S2). Next the pair forms the mating wheel, then the male transfers sperm from his hamules to the female through her genital pore under the eighth abdominal segment (S8). The beginning-to-end process is shown in the following still photos and two-part series of videos.

Digital Scans:

Copyright © 2015 Walter Sanford. All rights reserved.

Ebony Jewelwing damselflies (male, female)

August 9, 2015

Ebony Jewelwing (Calopteryx maculata) is a member of the Family Calopterygidae (Broad-winged damselflies). They are common from May to July along wooded slow-moving streams such as Dogue Creek in Wickford Park.

Male

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”).

An Ebony Jewelwing damselfly (Calopteryx maculata) spotted at Dogue Creek, Wickford Park, Fairfax County, Virginia USA. This individual is a male.

05 AUG 2015 | Wickford Park | Ebony Jewelwing (male)

The preceding image also shows the male hamules, …

paired structures that project from pocket under the second segment [S2] and hold female abdomen in place during copulationSource Credit: Glossary [of] Some Dragonfly Terms, by Dennis R. Paulson.

After a male damselfly grabs a female with his claspers, he transfers sperm from the genital opening under the ninth abdominal segment (S9) to his hamules, located beneath the second abdominal segment (S2). Next the pair forms the mating wheel, then the male transfers sperm from his hamules to the female through her genital pore under the eighth abdominal segment (S8).

A mating pair of Ebony Jewelwing damselflies (Calopteryx maculata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in wheel (in heart).

06 JUN 2015 | HMP | Ebony Jewelwing (mating pair, in wheel)

The copulatory, or wheel, position is unique to the Odonata, as is the distant separation of the male’s genital opening and copulatory organs. That the position looks as much like a heart as a wheel has been noted. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 377-378). Princeton University Press. Kindle Edition.

Female A simple field marker may be used to differentiate male and female Ebony Jewelwings: females feature white pterostigmata (see below); males don’t.

An Ebony Jewelwing damselfly (Calopteryx maculata) spotted at Dogue Creek, Wickford Park, Fairfax County, Virginia USA. This individual is an adult female.

05 AUG 2015 | Wickford Park | Ebony Jewelwing (adult female)

The preceding annotated image illustrates some of the reproductive anatomy of a female Ebony Jewelwing: a cercus (pl. cerci), one of two superior appendages that have little or no function; a stylus (pl. styli), one of two structures that serve as sensors in egg positioning; and an ovipositor that is used to insert eggs into submerged vegetation (endophytic oviposition). Notice the mud on the tip of the female’s abdomen, indicating she laid eggs recently.

Copyright © 2015 Walter Sanford. All rights reserved.


%d bloggers like this: