Posts Tagged ‘Family Macromiidae (Cruisers)’

Kaizen

August 2, 2022

In Japanese, the word “kaizen” literally means improvement.

The Japanese word kaizen means ‘change for better,’ with the inherent meaning of either ‘continuous’ or ‘philosophy’ in Japanese dictionaries and in everyday use. The word refers to any improvement, one-time or continuous, large or small, in the same sense as the English word improvement. Source Credit: Kaizen, Wikipedia.

I wonder whether regular readers of my blog have noticed that many posts are updated and/or improved after they are posted. And so it is with the Identification Guide for Family Macromiidae (Cruisers) in Virginia that was published recently.

We corrected a typo (changed “boarder” to “border”) that spell-check missed, added a pointer to a range map for the two subspecies of Swift River Cruiser (see Related Resources), and updated the interactive version of the PDF (already published).

Finally we created a new, non-interactive version of the PDF. The following screenshot shows what the new document looks like.

(See the complete, non-interactive PDF version of the ID guide.)

Related Resources

Copyright © 2022 Walter Sanford. All rights reserved.

Identification Guide for Family Macromiidae (Cruisers) in Virginia

July 15, 2022

There are two (2) genera and five (5) species in Family Macromiidae (Cruisers) that can be found in the Commonwealth of Virginia.

Stream Cruiser (Didymops transversa). MAR 26 – SEP 11.

Allegheny River Cruiser (Macromia alleghaniensis). JUN 4 – AUG 27.
Swift River Cruiser (Macromia illinoiensis) MAY 08 – OCT 10. [This species includes two subspecies: Macromia illonoiensis illinoiensis; and Macromia illinoiensis georgina.]
Mountain River Cruiser (Macromia margarita). MAY 25 – JUN 15.
Royal River Cruiser (Macromia taeniolata). MAY 15 – OCT 10.

Source Credits: A Checklist of North American Odonata
Including English Name, Etymology, Type Locality, and Distribution, by Dennis R. Paulson and Sidney W. Dunkle. Adult flight periods excerpted from “CHECKLIST OF THE DRAGONFLIES AND DAMSELFLIES OF VIRGINIA, April 2017 and April 2020 updates” by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage.

General Characteristics for Cruisers

All cruisers have a single stripe on the lateral sides of their thorax. All cruisers have spots on top of their frons with the notable exception of Royal River Cruiser (Macromia taeniolata), a key field mark for that species.

Genus Didymops

Stream Cruiser

Stream Cruiser (Didymops transversa) is so distinctive in its appearance that no other species of dragonfly looks similar.

Photo credit: Walter Sanford. Stream Cruiser (male).

The following composite image shows two (2) female terminal appendages in the background photo; three (3) male appendages are shown in the inset photo.

Photo credit: Walter Sanford. Stream Cruiser (female).

Genus Macromia

In contrast with genus Didymops, the four species of genus Macromia look similar and can be difficult if not impossible to identify with certainty in the field (especially females of some species).

Accordingly, this identification guide will focus on genus Macromia. Our advice (say it over and over like a mantra): Shoot first (photos, that is) and ask questions later. At a minimum, we recommend photos that show both a dorsal view and lateral view. The more the better! All of that being said, be sure to get at least one “record shot” — get a shot, any shot, and refine the shot as the subject allows.

Photo-illustrated guides for each species in genus Macromia are divided into two sections: one part for males; another part for females. The following field marks can be used to differentiate male versus female dragonflies.

Male: hamules (secondary genitalia located underneath abdominal segments two and three (S2-3); three (3) terminal appendages including two (2) cerci and one (1) epiproct; and “indented” hind wings.

Female: thicker abdomen, no hamules; two (2) cerci; and rounded hind wings.

A three-step process can be used to determine the identity of species in genus Macromia.

  1. Examine the anterior side of the thorax for the presence or absence of prominent frontal stripes, sometimes referred to as antehumeral stripes. This is a key field mark.
  2. Examine the pattern of abdominal bands and spots. Bands on abdominal segments two and seven (S2 and S7) are key field marks. They can appear to be complete or broken dorsally, complete or broken laterally, or can encircle the entire abdominal segment.
  3. Examine the pattern of wing venation, as necessary, specifically the forewing triangle.

Females of Allegheny River Cruiser, Swift River Cruiser (especially the “Illinois” subspecies), and Mountain River Cruiser can be extremely difficult to identify.

Females can be very difficult to distinguish. Source Credit: Paulson, Dennis. Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 7243). Princeton University Press. Kindle Edition.

Where the ranges of the two subspecies of Swift River Cruiser overlap (including the eastern Piedmont and Coastal Plain of Virginia) individuals with intermediate characteristics might be encountered. It will be impossible to assign these individuals to either subspecies. (Donnelly and Tennessen 1994).



Prominent frontal stripes are present in two species of genus Macromia: Royal River Cruiser (Macromia taeniolata); and Swift “Georgia” River Cruiser (Macromia illinoiensis georgina).

Royal River Cruiser

Male field marks: No pale spots on top of frons; prominent frontal stripes; no club.

Photo used with written permission from Larry Lynch.

Female field marks: No pale spots on top of frons; prominent frontal stripes; either small paired spots or no spots at the base of abdominal segment eight (S8).

Photo used with written permission from Larry Lynch.

Swift “Georgia” River Cruiser

Male field marks: Pale yellow spots on top of frons; prominent frontal stripes; prominent club.

Photo used with written permission from Joseph Girgente.

Female field marks: Pale yellow spots on top of frons; prominent frontal stripes; prominent yellow crossbar or band at base of abdominal segment eight (S8).

Photo used with written permission from Larry Lynch.



Prominent frontal stripes are absent in three species of genus Macromia: Allegheny River Cruiser (Macromia alleghaniensis); Swift “Illinois” River Cruiser (Macromia illonoiensis illinoiensis); and Mountain River Cruiser (Macromia margarita).

Allegheny River Cruiser

Editor’s Note: Frontal stripes are present in many individuals, but they are generally short and less prominent.

Male field marks: Band on abdominal segment two (S2) slightly broken dorsally, complete laterally; band on abdominal segment seven (S7) completely encircles the abdomen; mesotibial keel length <20%. [See Michael Moore’s excellent annotated images for good illustrations of mesotibial keels.]

Photo credit: Walter Sanford. Specimen collected by Mike Blust.

Photo used with written permission from Larry Lynch.

Female field marks: Band on abdominal segment two (S2) broken dorsally, complete laterally; band on abdominal segment seven (S7) broken laterally.

Photo credit: Mike Boatwright.

Photo credit: Mike Boatwright.

Swift “Illinois” River Cruiser

Male field marks: Band on abdominal segment two (S2) narrow and broken both dorsally and laterally; band on abdominal segment seven (S7) incomplete laterally; generally little or no yellow spots on middle abdominal segments; mesotibial keel length 25-50%.

Editor’s Note: This is the only species of genus Macromia with black auricles.

Photo credit: Mike Boatwright.

Photo used with written permission from Larry Lynch.

Female field marks: Band on abdominal segment two (S2) broken dorsally and laterally; band on abdominal segment seven (S7) broken laterally; spots on dorsum of abdomen generally smaller and more triangular than those of Mountain River Cruiser.

Some females might not be identifiable without in-hand examination of the subgenital plate, tibia length, and wing venation (refer to the section entitled “Wing Venation” toward the end of this guide).

Photo credit: Mike Boatwright.

Mountain River Cruiser

Editor’s Note: Yellow stripe on the face is brighter with a more narrow brown border.

Male field marks: Band on abdominal segment two (S2) broken dorsally, complete laterally; band on abdominal segment seven (S7) incomplete laterally; mesotibial keel length >50%.

Photo credit: Mike Boatwright.

Photo credit: Mike Boatwright.

Female field marks: Band on abdominal segment two (S2) broken dorsally and laterally; band on abdominal segment seven (S7) broken laterally; spots on dorsum of abdomen fairly large and squarish.

Photo credit: Mike Boatwright.

Photo credit: Mike Boatwright.



Wing venation

Wing venation can be used sometimes in conjunction with other characteristics to help distinguish some species of Macromia (river cruisers). However, there is variability within species. In addition, some individuals may exhibit different venation in each wing. Females generally have more crossveins than males. Therefore, one must not rely upon wing venation solely to make a positive identification. The information given here was derived from several scientific sources and represents the most commonly observed venation of both sexes within a species.

Mountain River Cruiser: Forewing triangle usually two-celled and subtriangle usually bordered by three cells; subtriangle one- or two-celled.

Photo credit: Mike Boatwright.

Photo credit: Mike Boatwright.

Allegheny River Cruiser: Forewing triangle usually one-celled and subtriangle usually bordered by two cells; subtriangle usually one-celled.

Photo credit: Mike Boatwright.

Mountain River Cruiser: Forewing triangle 2 celled (90%) and subtriangle bordered by 3 cells (75%); subtriangle 2 celled (55%).

Allegheny River Cruiser: Forewing triangle 1 celled (100%) and subtriangle bordered by 2 cells (100%); subtriangle 1 celled (90%).

Swift “Illinois” River Cruiser: Forewing triangle 1 celled (90%) and subtriangle bordered by 2 cells (70%); subtriangle 1 celled (100%).

Swift “Georgia” River Cruiser: Forewing triangle 2 celled (75%) and subtriangle bordered 2 cells (65%); subtriangle 1 celled (75%).

Royal River Cruiser: Forewing triangle 2 celled (75%) and subtriangle bordered by 3 cells (90%); subtriangle 2 celled (90%).

Editor’s Note: Percentage (%) refers to the percentage of wings showing the venation patterns, among study specimens. (Williamson 1909, and Westfall 1947).



Related Resources

Credits

Thanks to Larry Lynch and Joseph Girgente for permission to use their excellent photographs in this guide.

Also sincere thanks to my good friend Mike Boatwright, without whom it would have been impossible for me to create this guide. Mike is a master at odonate identification based upon key field marks — his descriptors provide the essential framework for the guide. And Mike did most of the heavy lifting by annotating all but two of the images featured in this guide. Excellent work, Mike that I’m honored to be able to share with our fellow odonate enthusiasts.

Copyright © 2022 Walter Sanford. All rights reserved.

Beware of look-alikes!

September 28, 2021

Some species of dragonfly larvae/exuviae look similar to other species. Here are a couple of look-alikes from two different families that might fool you.

One species of Corduliidae in our region [North America], Epitheca princeps, resembles the macromiid general body shape and is nearly as large, but the legs are short compared to its body dimensions and it lacks a triangular frontal projection. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 329.

The first annotated image shows a ventral view of a Prince Baskettail (Epitheca princeps) exuvia. E. princeps is a member of Family Corduliidae (Emeralds).

Notice the appearance of the E. princeps exuvia is quite similar to the Stream Cruiser (Didymops transversa) exuvia shown below. D. transversa is a member of Family Macromiidae (Cruisers).

The E. princeps exuvia features lateral spines and well-developed mid-dorsal hooks on some abdominal segments. Notably “it lacks a triangular frontal projection” (K. J. Tennessen), or stated more simply, there isn’t a “horn” on its face-head.

The D. transversa exuvia also features lateral spines and mid-dorsal hooks, as shown below. Notice the mid-dorsal hooks aren’t as cultriform as E. princeps. In contrast to the E. princeps exuvia, notice the prominent “horn” on the face of the D. transversa exuvia. It’s all about the “horn.”

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Macromiidae – It’s all about the “horn.”

September 24, 2021

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

Look closely at the full-size version of each of the following photos and you should be able to see the horn on the face of a Stream Cruiser dragonfly (Didymops transversa) exuvia that was collected during mid-April 2021.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (face-head)

It’s easier to see the horn in the next photo…

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

The horn is clearly visible in the last photo. Notice there are three “bumps” located between the eyes of the exuvia: the middle bump is the horn; the antennae bases are located to the left and right of the horn.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Test shots: Didymops transversa exuvia

September 21, 2021

An exuvia from a Stream Cruiser dragonfly (Didymops transversa) was collected from one of the concrete abutments of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

I prefer to photograph odonate exuvia like this one “as is” — presumably its appearance is similar to the way larva looked when it lived underwater.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

If so, then I’m guessing D. transversa larvae are bottom dwellers, as indicated by the dirty, sediment-covered dorsal side and relatively clean ventral side of this specimen.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (ventral)

Post Update

The nymphs are sprawlers that cling to roots or hunker down in sediments of mixed sand and silt particles. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 330.

The Backstory

The preceding photos were shot using the prototype for a homemade curved clear plastic tray intended for staging subjects against a white background.

With a few minor tweaks, the curved stage performed better than during initial testing. I needed to add a second external flash unit to more evenly illuminate the white background.

Although I’m fairly satisfied with the results of these test shots, more testing is required to be sure the set-up is working the way I want.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Stream Cruiser dragonfly (female)

May 18, 2021

A Stream Cruiser dragonfly (Didymops transversa) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This individual is a female, as indicated by her thick abdomen and terminal appendages.

13 MAY 2021 | Prince William County, VA | Stream Cruiser (female)

The female was perched in a large field near the same location where Mike Powell found a Stream Cruiser exuvia on 13 April 2021.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Exuvia from Family Macromiidae (Cruisers)

May 14, 2021

Michael Powell spotted a large odonate exuvia clinging to the concrete abutment of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This cast skin is definitely from a member of Family Macromiidae (Cruisers), as indicated by its long legs and the shape of its body.

13 APR 2021 | Prince William County, VA | Stream Cruiser (exuvia)

Mike’s macro photo of the same subject (shown below) turned out better than mine, taken with a superzoom bridge camera. Look closely at the full-size version of Mike’s photo. Nothing says Family Macromiidae (Cruisers) like the “horn” on the front of the face/head of the exuvia!

Photo used with written permission from Michael Powell.

The following excerpt from Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, shows the couplet that I think indicates this specimen is from a Stream Cruiser dragonfly (Didymops transversa).

The adult flight periods for the three species of cruisers found in Northern Virginia provide circumstantial evidence in support of my tentative identification. Source Credit: “Dragonflies of Northern Virginia” Web site by Kevin Munroe.

What’s next?

The specimen was collected in order to shoot a complete set of macro photographs of the exuvia in my home “studio.”

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Swift River Cruiser exuvia (face-head)

November 20, 2020

The following image is a focus-stacked composite of three photos, focused on the left eye, right eye, and both eyes respectively.

27 May 2017 | Riverbend Park | Swift River Cruiser (exuvia, face-head)

Tech Tips

The dragonfly exuvia was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.

Several photos were taken using my Canon EOS 5D Mark II digital camera, a Kenko 12mm extension tube, and Laowa 25mm Ultra Macro Lens, set for f/4.0 (the sweet spot for this lens) at ~3.0x magnification.

Godox TT685C external flash was used to backlight the background (a piece of translucent white plastic) and a Godox TT685F external flash was used as a key light on the right side of the subject. The flash was triggered wirelessly by a Godox X2TC.

Check the EXIF/IPTC info for the photograph for complete details regarding photo gear and camera settings.

Adobe Photoshop CC 2017 was used to create a focus-stacked composite image that was edited using Apple Aperture.

The Backstory

Swift River Cruiser dragonfly (Macromia illinoiensisexuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female.

Copyright © 2020 Walter Sanford. All rights reserved.

When is close too close?

October 14, 2020

Swift River Cruiser dragonfly (Macromia illinoiensisexuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female. The prominent horn on the head — a key field mark for exuviae from Family Macromiidae (Cruisers) — is noticeable in the following photo, although maybe not recognizable.

This photo is one of several test shots using “The Macroscope,” my nickname for the Laowa 25mm Ultra Macro Lens. The Laowa lens was mounted on my Canon 5D Mark II digital camera with a 12mm Kenko extension tube between the lens and camera body.

My new Laowa LED Ring Light was mounted on the front of the lens, powered by an Anker PowerCore+ 26800 PD 45W battery. The Laowa LED Ring Light was used to light the subject. A Sunpak LED-160 Video Light was used as a focusing aid. A Godox TT685C external flash was used to backlight a translucent white plastic background, using the “Meet Your Neighbours” technique. The flash was triggered wirelessly by a Godox X2TC.

The image is full-frame (5616 by 3744 pixels), that is, uncropped. The lens was set for f/4 (the “sweet spot” for the lens) at 4x magification. The camera was set for single point focus and spot metering, centered on the right eye of the exuvia.

Look closely at a full-size version of the image. At this magnification, the depth of field is very shallow: remnant ommatidia are clearly in focus; most of the image is out of focus.

In order to provide some context for what is shown in the first photo, the last photo shows the entire specimen. The photo gear used to take the shot is specified in a previous blog post.

When is close too close?

Close is too close when most of the subject is unrecognizable. At 4x magnification, it’s essential to use focus stacking to create a composite image.

The bigger take-away from this test shot is the Laowa LED Ring Light seems to work fairly well, albeit a sample size of one.

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

More experimentation with tethered shooting

August 12, 2020

Oh no! I have become the blogger who cried wolf. Yes, I’m guilty of over-promising and under-delivering. I promise to do better. Oops, I did it again! (Queue Britney Spears…)

Why tethered shooting?

In case you’re wondering what piqued my interest in tethered shooting, I was bored. I had figured out all there is to know about non-tethered shooting so I needed a new challenge. Not!

Tethered shooting enables me to quickly check composition, exposure, and focus, to name a few advantages of tethered versus non-tethered shooting — on a larger screen than the LCD on the back of my cameras.

Bear in mind, I don’t want to edit the photo files using my laptop computer (Apple 11″ MacBook Air) — I prefer to use my desktop computer (Apple 24″ iMac) for photo editing.

Latest testing

The following photos were taken by tethering my Fujifilm X-T3 digital camera to an Apple 11″ MacBook Air computer, via a TetherTools USB cable. FUJIFILM Tether Shooting Plug-in PRO was used to save JPG files to a folder on the desktop of my MacBook Air; in turn, the JPG images were displayed in Adobe Lightroom. Both JPG and RAF files were saved to one of two memory cards in the X-T3.

Notice the difference in way these two photos were lighted. Both shots were taken using a single off-camera flash. The position of the flash resulted in more- or less dramatic light. Each shot shows something better than the other, so I was unable to choose a clear favorite. What’s your preference?

Tips and Tricks

Oh yeah, the tips and tricks I have been promising are still in the pipeline. I made some screen grabs today to illustrate the process of tethered shooting. Turns out I overlooked a critical setting so all of the graphics are useless. Doh! Can you say “Do over”?

Copyright © 2020 Walter Sanford. All rights reserved.


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