My friend found this one last year in a small stream at high elevation (see the entry of 3/5/13) -- but for me, this was a first. This is the Nemourid stonefly, genus Soyedina. I found two of them today in one of my favorite streams for looking for insects. We have to leave this at the level of genus since only a few of these nymphs have been described to the level of species. I can tell you that only two species are attested for the state of Virginia (Stewart and Stark, Nymphs of North American Stonefly Genera, p. 217) -- S. carolinensis and S. vallicularia. Stewart and Stark provide illustrations of S. vallicularia (pp. 215-216), and I'd have to say I don't think that's the species we're finding.
Beaty says that Soyedina is "relatively rare," and describes it in the following way: "Nymphs 6.5-8.5 mm; pronotum with angular corners and a distinct posterolateral notch, with well developed lateral fringe; wing pads divergent; anterior thoracic gills absent." ("The Plecoptera of North Carolina," p. 5) Stewart and Stark note the key diagnostic characters in the following way: "The short legs and fringed, notched rectangular pronotum distinguish Soyedina nymphs from the nymphs of other non gilled genera.
The nymphs that I found were young and about 6 mm in length. It is the fore femora which are especially short, and we can see that in the photo above. For the other features -- pronotal notch with dense lateral fringe and divergent wing pads -- the photos my friend took last year show them better than anything I managed to get.
The divergent wing pads:
The pronotal notch and lateral fringe:
The nymphs she found -- like those that I found this morning -- were a little bit "muddy," but these are nymphs that are typically "found in leaf packs in seeps and small, cold streams." (Beaty, p. 5)
Love finding new things!
But I made lot of good findings this morning.
1. The first Taenionema atlanticum large winter stonefly of the season.
In another 1-2 months they'll be looking like this.
2. A Lepidostomatid (genus Lepidostoma) in a very nice case made of sand.
3. And three Uneoids that had also made very colorful cases.
Number one was Neophylax oligius: two and three will require more work. They appear to be the same species that I found at the Rapidan River, i.e. N. atlanta.
Nice day at a beautiful stream.