Sunday, May 5, 2013
Cinygmula subaequalis in the small streams in Sugar Hollow
With rain and clouds in the forecast for much of the upcoming week, I decided to head to one of the small streams in Sugar Hollow this morning. The bottoms of the rocks were still covered with Epeorus pleuralis, and the leaf packs were filled with free-living caddisfly larvae (Rhyacophila fusculus -- the green ones), and, of course, lots of spiny crawlers.
Still I found some new things -- pleasant surprises. Heading the list, this flatheaded mayfly, Cinygmula subaequalis. I've only seen this one other time -- in South River up in Greene County in March of last year (see the posting for 3/27/12). It is not very common, and as Beaty points out ("The Ephemeroptera of North Carolina," p. 17), they are only found "in high quality mountain streams." (The TV is 0.0.) This is a flatheaded species that, if you look closely, you can pick out by sight. The maxillary palps can be seen from above, sticking out from the sides of the head. They look like little "horns."
Of course they're easier for us to see in a microscope view, as is the "medial notch" at the front of the head (Beaty, p. 17).
C. subaequalis is the only Cinygmula species that is found in the East, but there are 9 species out West. There it hatches in streams in July through September as the "Dark Red Quill." (Knopp and Cormier, p. 171). I don't think C. subaequalis provides a significant hatch for fishermen in the East.
Two other treats -- two insects that we've been seeing all winter long that are maturing, getting ready to hatch.
1. The "Roach-like" stoneflies, Peltoperlids, genus Tallaperla. Note the black tips on the wing pads.
2. And a Chloroperlid -- Green stonefly -- genus Sweltsa.
I keep hoping to ID these to the level of species, but Beaty advises to leave our ID at genus. However, I did note this morning that he may help us with this one -- we might call it Sweltsa mediana. "Nymphs of most species are undescribed although members of the Sweltsa mediana group have a median dorsal abdominal stripe and includes S. urticae and S. voshelli." (Beaty, "The Plecoptera of North Carolina," p. 10). The nymphs that I see, when they mature, always have that mid-dorsal stripe.
I was hoping to see lots of Perlodid stoneflies this morning -- but I didn't. There were quite a few Isoperla holochloras around, but they're still on the small side.
I did see my first Remenus of the spring/summer season. I think of this as the "last" of the Perlodids -- it's the last species to make its initial appearance. This one was tiny.
They do grow into quite pretty nymphs, witness this one that I found in May of last year at the Rapidan River.
Defining feature? The lacinia. "Lacinia unidentate, with a widely shallow base and with a single, long tooth." (Beaty, "The Plecoptera of North Carolina," p. 26) Looks like this.