We're getting there -- but still not quite mature. When they're mature, their wing pads will be easy to see, as in this nymph that I found two years ago in the same stream at much the same time (1/30/12).
While almost every small winter stonefly we see is Allocapnia in terms of the genus, these are Paracapnia, and it's the shape of the wing pads that gives them away: the posteriors of the front and back wing pads are round. On Allocapnia nymphs the rear wing pads are truncate. While you can make out the wing pads on the nymph in the photo at the top of the page, they're much sharper in this microscope view.
Beaty, however, prefers to use other traits for identification: 1) the body is very setose (hairy), and 2) there is a "purplish-brown reticulate color pattern on [the] head." ("The Plecoptera of North Carolina", p.1) Both are clear in this photo.
Paracapnia angulata -- the only species we find in the southeast -- "typically occurs in small headwater streams," which is where I was yesterday. Accompanied by my friend who lives in Sugar Hollow, I returned to the stream where we found very small nymphs of this species on December the 3rd of last year. I had no problem finding these uncommon nymphs in the leaf packs. NC has not assigned a tolerance value to P. angulata, which usually means they've not found very many. Size of these nymphs: 6 mm.
2. Uenoids. I had no trouble finding Uenoids, but the cases I saw were still very small.
But it was worthwhile to photograph some and then check the ID since I found the two "best" species we've seen so far in our streams: Neophylax mitchelli (below in this photo) and Neophylax aniqua (at the top). N. mitchelli has a TV of 0.0; N. aniqua has not been assigned a TV in NC -- not enough found. While I got some good photos of both caddisflies, I could not see what I needed to see for identification: the tubercles on their heads. Well, I could almost see them.
The tubercle on N. mitchelli is long and pointed, "usually directed somewhat posteriorly" (Beaty, "The Trichoptera of North Carolina," p. 87) while that of N. aniqua is "often semi-blunt" (Beaty, p. 86). Seen through the microscope they show quite well.
N. aniqua is said to occupy "the most upstream position in the longitudinal sequence of species in streams where it occurs" and "is restricted to springs and first-order streams." (Vineyard, et.al., The Caddisfly Genus Neophylax, p. 43) The same source notes that "N. mitchelli has been collected from the same habitats as N. ornatus ... N. atlanta, and ... N. aniqua." (Vineyard, et.al., p. 56)
By the way, I stopped further downstream and looked for Uenoids above the first bridge in Sugar Hollow -- here
-- they were all N. fuscus: no tubercle, no clavate ventral gills, muscle scars at the back of the head.
A three species day!
Two other photos:
1. The flatheaded mayfly Maccaffertium pudicum, the one that is often found in headwater streams with M. merririvulanum.
2. And above the first bridge, the large winter stonefly Strophopteryx fasciata.
Oh. While I was lifting rocks and sorting through leaf packs, my friend was digging in the substrate where she found a small Ephemera nymph, a "common burrower." You can be sure we'll be back here in the spring in hopes of finding one that's mature. In May, 2012, we found this mature Ephemera guttalata in a small headwater stream on the other side of the valley. Very cool!