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Willmilne has attached this picture to aid in identification. The message is below.
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WillmilneJuly 3rd, 2008, 2:38 pm
Manitoba Canada

Posts: 19

Found some of these lovely nymphs while out - any suggestions as to species?



GONZOJuly 3rd, 2008, 4:04 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
My first impression is that it is a Maccaffertium (formerly Stenonema) nymph. That said, however, you have some heptageniids up there with which I am not at all familiar. It is a very striking specimen and ripe to hatch (a "blackwing"). Perhaps Roger or Konchu can offer another opinion.
TaxonJuly 3rd, 2008, 11:15 pm
Site Editor
Royse City, TX

Posts: 1350

These are the two Heptageniid nymphs on Will's website. I arranged them similarly aligned for comparison purposes.

In late May, I suggested the one on the left was probably Leucrocuta maculipennis. My guess is that the one on the right may be either Heptagenia flavescens or Maccaffertium modestum. How's that for hedging?

In any event, Will certainly does have a talent for photographing aquatic insects.
Best regards,
Roger Rohrbeck
WillmilneJuly 4th, 2008, 7:39 am
Manitoba Canada

Posts: 19
Thanks for the suggestions on ID.So much to learn. I guess I have to start learning to photograph the key details and get a little more focused. I am at the moment simply taken with the beauty and subtle variations of color in these, sometimes at first glance , rather drab looking insects. Glad you are enjoying the pics Roger.

Would you think this is the same species at a different stage, the markings are very similar - it was collected at the same time. Much lighter and more yellow olive in tone and lacking the lower leg banding.


GONZOJuly 4th, 2008, 10:10 am
Site Editor
"Bear Swamp," PA

Posts: 1681

The photo in the link does appear to be the same species, but not as "ripe" yet. Overall, I am leaning toward a Maccaffertium ID because the gills look more like that genus than Heptagenia to me.

By the way, I came across a recent article in the Journal of Insect Science that proposed a new species, Heptagenia whitingi (considered a sister taxon of H. flavescens). The dorsal photo included in the article appeared to match the markings of your other specimen (the one on the left in Roger's comparison) almost exactly, except that it is a paler version (probably due to preservation in alcohol). What first caught my attention was the mention of the large, pale rectangular markings on abdominal tergum 4 as an important diagnostic character. (However, please note the comment about H. adaequata in the larval diagnosis.) The other interesting aspect was the use of DNA "barcoding." It's just a thought, but you can find the article at:

(I wish I could make that a direct link, but I can't seem to get BBCode to work here. My computer skills suck, so I'm probably doing something wrong.)
DhfunkNovember 15th, 2008, 10:51 am
Avondale PA

Posts: 2
H. whitingi seems reasonable for the one on the left. The one on the right looks a perfect match for Stenonema femoratum. If you were to flip the specimen over and find a series of dark sublateral spots on each side of the abdominal segments, that would nail it.
GONZONovember 15th, 2008, 12:30 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Nice of you to pick up on this one, David. I sometimes forget to consider femoratum now that it is stranded on its own. The illustration in Spieth (of "S. femoratum tripunctatum," 1947) and especially the photo in Lewis (of "S. tripunctatum," 1974) do look very much like Will's other specimen. Thanks for pointing things in the right direction!

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