Blue-fronted Dancer color change?

I've been photographing dragonflies and damselflies for some years. My interest began in an opportunistic way, usually when out looking for birds.  When I saw this beautiful dragonfly perched on a stem on June 12, 2015, I had no idea what it was and didn't find out until 2023!  I have often admitted to being a poor archivist of my photos and, by accident, came across this photo again and pursued the ID further.    

Four-spotted Skimmer (Libellula quadrimaculata), Upper Peninsula, Michigan

This remains the only Four-spotted Skimmer I have ever seen, but my interest in Odonata has increased and my knowledge base has improved slowly since 2015.  Not just in identification, which some would argue remains poor, but in other areas of recognition as well.  

Still, because of the judgment from others that comes with being a novice, I am often reluctant to draw attention to some observations that have intrigued me.  Whether identifying an odonate, a bird or a bumblebee incorrectly, no one likes being treated dismissively.  I love learning so I press on and try to ignore the noise.

Today while perusing some odonate websites, articles and literature I found this blogpost: Physiological Color Change in Argia Apicalis, by Dr. Amanda Whispell of Rutgers University (where PhD earned); I believe she now lives in Virginia.  I recalled the Blue-fronted Dancers (Argia apicalis) I found in early July (2024) at Lower Huron Metropark in Michigan.  When it came time to enter my location list into Odonata Central (OC), I held back on entering an unexpected sighting and stuck with the more typical-appearing Blue-fronted Dancer for the OC photo entry.

All of my photos below are of Blue-fronted Dancers seen on the same day, in the same area and around the same time generally.

Above and below:  Male Blue-fronted Dancer (Argia apicalis)

But it was the Blue-fronted Dancer in the photo below that intrigued me.  A green thorax on Blue-fronted Dancer?       

In the field, I distinctly recall thinking that the brown-form damselfly above was a female Blue-fronted Dancer.  But when I downloaded the photos and was able to look more closely at them it did not match the female photos I had or of others that I found on-line.

Females do not have the little dark notch (arrow) on their thorax - (I would describe the female mark as more of a "sliver") - and it is really not a notch but appears so in the lateral view.  Nor do they have the extensive color in abdominal segments 9 and 10.  If I use my imagination, it even appears that S9 and S10 are in the early stages of turning blue.  So is this an immature male?  For now, this is my guess.

Above and below:  So is this brown-form Blue-fronted Dancer an immature male or an adult female?  The arrows show the differently-shaped thorax mark - the "sliver" - and the abdominal segments 9 and 10 also appear different.  S9, S10 appear more swollen and the tan color is less extensive.  So, is this an adult brown-form female?  For now, this is my guess.  (I don't have a photo of a blue-form adult female).

But what about the Blue-fronted Dancer with the green thorax?  In her study, Dr. Whispell writes:  "A. apicalis males possess the unique ability to change color, from BP to DP, (BP = blue phase; DP = dark phase), in response to copulation, and given the past research into the selective advantage of physiological color change, the ability to change color in direct response to copulation could provide them with a significant adaptive advantage."   The author makes no mention of the male's thorax turning green with mating.

However, Dennis Paulson in his 2011 tome Dragonflies and Damselflies of the East, page 149, describes female Blue-fronted Dancers as follows:  "Polymorphic, eyes brown darker above; lack of blue in eyes in andromorph good distinction from male."  He concludes his description with:  "Ovipositing blue females also become duller, blue-gray.  Some females are green and color change with age documented in individual females."

Based on my interpretation of Paulson's description, this seems to be an aberrantly colored thorax of a female Blue-fronted Dancer, a recognized variant.  I found this female before she had aged into the more typical color with either brown-form or blue-form thorax.  Also, S9 and S10 do not yet show tan coloring; although the abdominal tip is not well-focused, it appears to show signs of color changing.     

Why did I even bring up the research article in this photo discussion? Had it not been for Dr. Whispell's brief blogpost with her research, I would never have gone back to take a look at my green Blue-fronted Dancer.  It would still be the same mystery is was on the day I saw it.  Will I see this variant again?  So, far I haven't.  It also goes to show how tricky damselfly identification is.  I have made significant strides this summer, but not enough to move me from novice to intermediate.  The more I see, the more I'll understand and recognize in future sightings.

This is how learning goes.  Impatience and irritation does not help. This is a reminder to me to avoid the impatient, irritated approach with both myself and others.     

References:

1.  In addition to Dennis Paulsen's well-known Dragonflies and Damselflies of the East, 2011, Princeton University Press, I also use Damselflies of Minnesota, Wisconsin & Michigan by Robert DuBois with photos by Mike Reese.  Remarkably the DuBois book can be purchased at Target which I have linked above.  It is also on the Kollath & Stensaas Publishing website.  (An earlier edition titled Damselflies of the North Woods covering 44 species is purple.  Don't buy that one,)

2.  For this piece I also used the brand new A Naturalist's Guide to the Odonata of Ohio, by Dave McShaffrey, Malisa Spring and Jim McCormac, Ohio Biologic Survey, 2024.  The photographs of A. apicalis on page 88 are large and clear.  Describing female Argia apicalis the authors write:  "Females are trickier to recognize."  They go on to describe blue and brown morphs, but make no mention of a green morph.  They also write:  Blue forms of both sexes can noticeably darken the thorax from light blue to dark gray.  Many observers notice this darkening when the dancers are in tandem; however, a published study did not find such a correlation."  I recommend this guide for the excellent and large photos, but also for the extensive, clear and very well-written species descriptions.  I try to avoid linking any book to Amazon, but unfortunately this book is quite expensive on the publisher's website.  It will be cheaper purchased elsewhere.

3.  I found this excellent website, Delmarva Dragonflies and Damselflies by Mike Moore. which I keep going back to over and over, sometimes just to look at the photos, but also to use for identification assistance.  I used to live in Baltimore and was a frequent visitor to Maryland's Eastern Shore.  In the summer of 2018 I returned and, along with friends, rented a house on the Chesapeake Bay in Talbot County.  Finding and photographing odonata made this an extremely enjoyable vacation.  Mike Moore is an Odonata Central Admin reviewer and helped with several of my Talbot county submissions.  He also recently helped me with some of my Midwest submissions.     

No photo guide or website is going to be 100% useful for making identifications.  The experts will tell you that, when in doubt, you need to net the odonate and use a magnifier.  True enough, but easier said than done - at least for me.  I recently caught two red meadowhawks by hand and took poor photos of the gentalia with my iPhone 14.  I still could not make the field marks match an ID with confidence.  The only thing to do is continue trying and learning.  

All comments are welcome, but comments with corrections are especially welcome!