Archive for November, 2021

“Tech Tips” Tuesday

November 30, 2021

In this blog post I’m going to show you how I add special characters to some of my annotated images, such as the pictograph for “male,” shown below.

Photo used with written permission from Michael Powell.

I’ll show you how to do it on my older Apple 24″ iMac desktop computer (Early 2009), then I’ll show you (in more detail) how to do the same thing on my newer Apple 13″ MacBook Air laptop computer (M1, 2020).

macOS Yosemite (Version 10.10.5)

Open “System Preferences” and select “Keyboard.” Click on the tab labeled “Keyboard” and check the box for “Show Keyboard & Character Viewers in menu bar.”

As you might expect, a new icon will appear in the menu bar, located on the right side of the screen. When you click on the icon you should see three (3) options (listed from top-to-bottom): Show Character Viewer; Show Keyboard Viewer; and Open Keyboard Preferences… Select “Character Viewer” and navigate to Pictographs. (The last option takes you back the same screen that is shown above.)

macOS Monterey (Version 12.0.1)

After I was unable to figure out how to make the same setting on my MacBook Air, I referred to the “macOS User Guide” that is a built-in feature of the computer. A screenshot of the guide is shown below.

Open “System Preferences” and select “Keyboard.” Click on the tab labeled “Input Sources” and check the box for “Show Input menu in menu bar.”

A new icon will appear in the menu bar, located on the right side of the screen. When you click on the icon you should see the three (3) options shown below. Select the first option, “Show Emoji & Symbols.”

A new window will open on-screen. Navigate to Pictographs. Some sample Pictographs are shown below, including the female and male symbols (fifth row from the top).

Practical example using Photoshop

Here’s an example of part of my workflow to annotate a photograph using Adobe Photoshop.

Open a photo file in Photoshop. Select the “Text Tool” and create a new layer called “male symbol.” Click on the image to add an insertion point, then click on the “Show…” icon in the computer menu bar and select “Show Emoji & Symbols.” Navigate to “Pictographs” and select the “male sign.” You should see a list of “Font Variations.” I always use “Arial Bold.” Double-click on the icon and it should appear on the photo. ♂ Use the “Move Tool” to, well, move the symbol wherever you like on the image.

Photopea

I stumbled across an application recently called “Photopea” that is a free alternative to Adobe Photoshop. Photopea is a Web-based clone of Photoshop — Photopea doesn’t do everything Photoshop does but it could be used to annotate photos using a workflow similar to the one I just described. Look for one or more Photopea-related blog posts in the near future.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Happy Thanksgiving!

November 23, 2021

During the traditional time of year when we give thanks for our many blessings, I would like to thank everyone who follows/reads my blog.

I’m on a weeklong break for the holiday, but I’ll be back next Tuesday with a new post. In the meantime, “Happy Thanksgiving!”

Dark and moody

November 19, 2021

I spotted an emergent Uhler’s Sundragon (Helocordulia uhleri) during a photowalk along a mid-size stream at an undisclosed location in Prince William County, Virginia USA. The following photograph shows the exuvia from which the teneral adult emerged.

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

In the opinion of the author, larvae (nymphs)/exuviae from Family Corduliidae (Emeralds) and Family Libellulidae (Skimmers) can be challenging to differentiate and identify to the family level.

One way to differentiate Emerald from Skimmer larvae/exuvia is to look for a “ventromedial groove” in the prementum: it’s probably Corduliidae (Emeralds) if there is a ventromedial groove; it’s probably Libellulidae if there isn’t.

Look closely at a version of the preceding photo that was reformatted, rotated, and cropped to show an enlarged view of the prementum. You should notice a ventromedial groove on the basal half of the prementum, indicating this specimen is a member of Family Corduliidae (Emeralds).

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

Three raised structures on the underside of the prementum remind me of the hood ornament on a 1949 Lincoln automobile. (No, I wasn’t alive in 1949!)

Related Resources

Tech Tips

One reason I underexposed the photo is to add definition to the ventromedial groove and avoid overexposing the black background.

I prefer a white background for photographing odonate exuviae. Using a black background proved to be more challenging than I expected. More later in a follow-up blog post.

Copyright © 2021 Walter Sanford. All rights reserved.

How to estimate instar, revisited

November 16, 2021

I’m the founder and co-administrator of the Odonate Larvae and Exuviae Facebook group. Friday, 12 November 2021 was the two-year anniversary of the group. As of this writing there are approximately 1,700 members in the group, including people from around the world.

For example, Abiodun Matthew Adedapo from Nigeria. Abiodun began posting to the group relatively recently, sharing information and photos related to his research. Sincere thanks to Abiodun for permission to repurpose two of his photos for another mini-lesson on how to estimate instar.

What is the instar? Not F-0.

The equation for instar equivalent is as follows.

Instar equivalent = HwL / HW

Where HwL is Hind wing Length and HW is Head Width.

 

Photo used with written permission from Abiodun Matthew Adedapo.

I used the Adobe Photoshop “Ruler Tool” to measure the number of pixels along the two double-tipped white arrows shown in the preceding annotated image of a preserved specimen collected and photographed by Abiodun.

HwL is ~132.6 pixels. HW is ~195.12 pixels.

Instar equivalent = 132.6 pixels / 195.12 pixels

The units cancel, so the answer is ~0.68 — close to Ken Tennessen’s  average value for F-1 (final instar minus one).

Abiodun reported the instar as F-2, based upon in situ observations of a cohort of larvae (nymphs) from Family Gomphidae (Clubtails).

For my purpose, it doesn’t matter whether the actual instar is either F-1 or F-2 — the important take-away is we know the instar is not F-0, the final instar. This provides an opportunity to mention a simpler way to estimate final instar.

Larvae in the final stage can be recognized by the length of the wing buds which cover the fourth abdominal segment. Source Credit: Field Guide to the larvae and exuviae of British Dragonflies, by Steve Cham, p. 30.

Look closely at the first annotated image. Notice the length of the wing buds/pads doesn’t reach the fourth abdominal segment (S4) of the specimen therefore this larva is not in its final instar.

Thanks to Freda van den Broek for sharing this method with me!

F-0 (final instar)

The last annotated image shows part of a different larva also collected and photographed by Abiodun. Notice the length of the wing buds/pads does reach S4, therefore this larva is in its final instar.

Photo used with written permission from Abiodun Matthew Adedapo.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Mouth parts – Tiger Spiketail exuvia

November 12, 2021

I revisited a photograph featured in a blog post published several years ago. I wanted to annotate the image to include information that I learned recently.

The following annotated image shows the face and mouth of an exuvia from a Tiger Spiketail dragonfly (Cordulegaster erronea) after its scoop-shaped face mask was pulled away from the head in order to count setae on the inner side of the prementum.

Cordulegaster erronea | exuvia (face and mouth)

There are two mandibles, one located on each side of the labrum. And there are two maxilla, one located below each mandible. Coarse setae make it challenging to see all of the parts clearly.

Sincere thanks to Marla Garrison for verifying my tentative identification of these mouth parts. And of course, thanks to Mike Boatwright for collecting and sharing the specimen with me.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Anatomy & Functional Morphology of Dragonfly Nymphs

November 9, 2021

As a blogger I create and share content. Sometimes I share content created by others, such as the following YouTube video from the Dragonfly Society of the Americas (DSA).

“Anatomy & Functional Morphology of Dragonfly Nymphs,” DSA (48:58).

Marla Garrison, McHenry County College, Biology Faculty, was featured during a Zoom meeting on 24 September 2021 as part of a series of Virtual Lectures presented by the Dragonfly Society of the Americas.

Marla’s lecture is richly illustrated with spectacular still photographs and video clips. I think readers of my blog will enjoy Marla’s presentation.

Copyright © 2021 Walter Sanford. All rights reserved.

Post update: What is it — emerald or skimmer?

November 5, 2021

An exuvia from a Stygian Shadowdragon dragonfly (Neurocordulia yamaskanensis) was collected by Freda van den Broek on 10 June 2019 along the St. Croix River in Interstate Park, Polk County, Wisconsin USA.

The presence of a ventromedial groove in the prementum suggests this specimen is a member of Family Corduliidae (Emeralds) and in fact it is.

Congratulations to Douglas Mills, who correctly identified the family of this specimen.

Going with corduliidae for the groove. It’s got impressive crenulations — I had to double check they weren’t jagged and this was a trick question 🙂 Source Credit: Douglas Mills.

Douglas successfully avoided the trap that was set when I chose to use a specimen that features deeply-scalloped crenulations along the margins of the palpal lobes. According to Kevin Hemeon, member of the “Odonate Larvae and Exuviae” Facebook group, crenulations like these are a characteristic field mark for Genus Neurocordulia (Shadowdragons) in the Family Corduliidae (Emeralds).

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

What is it — emerald or skimmer?

November 2, 2021

Ladies and gentlemen, children of all ages. It’s time for another exciting episode of “What is it?

I wrote about the “ventromedial groove” in a recent blog post. Based upon what you learned, is the following odonate exuvia a member of Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers)?

Odonata (Suborder Anisoptera) | exuvia (face-head)

If you think you know the family, then please leave a comment. The answer will be revealed in a post update.

Copyright © 2021 Walter Sanford. All rights reserved.


%d bloggers like this: