I was excited to see this one this morning, thinking I had found the genus Nixe flatheaded mayfly. Alas, that wasn't the case: no fibrilliform behind the gills. It's a Maccaffertium, but a Maccaffertium I'm quite sure I've not seen before. What's the species?
Oh, how I wish I could tell you -- but I can't. I'll keep working on the species ID; maybe send it to Beaty for help. But Maccaffertium nymphs are notoriously difficult to take to the level of species. After describing 15 Maccaffertiums in his study of "The Ephemeroptera of North Carolina" (pp. 19-20), Beaty goes on to say, "This group is taxonomically difficult due to interspecies variability and often requires slide-mounts of mouthparts and legs to get a species level identification. Additionally, many species listed above may actually represent species complexes (particularly M. modestum) and therefore may result in the same species designation for specimens of different size classes and of variable characters. Immature specimens often do not key well and should, therefore, be left at genus."
We'll see. The legs have pronounced banding; the caudal filaments (tails) are banded as well; I do not see denticles on the tarsal claws; I do see both hairs and spine-like setae on the maxillary crown. It was only 7 mm, but it was fairly mature.
Other photos:
1. The spiny crawler mayfly, Drunella tuberculata, the first of the season.
Drunella spiny crawlers have the robust fore femora with tubercles/spines on the leading edge.
D. tuberculata nymphs have paired dorsal tubercles on the head.
It's a nymph that I commonly see at this time of year in Buck Mt. Creek and at the Doyles.
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2. A gorgeous, fully mature, Diploperla duplicata Perlodid stonefly.
3. and 4. A couple of Isoperla Perlodid stoneflies. The first, I. dicala...
the second, I. holochlora.
5. And in the bottom left of the photo above, the common stonefly, genus Perlesta, another first for the season. This is a genus we only see from May through the July. I found 3-4 Perlestas today: not sure I chose the right one for a photo.
6. And another first for the season, our "summer" Epeorus flatheaded mayfly, Epeorus vitreus.
The key feature is the "four irregular pale spots on the anterior margin of [the] head" (Beaty, p. 17), but the veination in the gills -- I think -- is also distinctive.
The water's still running high -- with more rain coming tonight. Ugh! And, it was dark and foreboding when I set out this morning. Still, I did get a few peeks of sunlight for photos: the ring light helped as well.
Now back to work on this problematic flathead.
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