The Uenoids (little northern casemakers) at the Rapidan River: best bet is Neophylax atlanta

Now back to the species ID of the Uenoids I found yesterday.    Everything points to Neophylax atlanta, a species that is "apparently rare" according to Beaty ("The Trichoptera of North Carolina, p. 86).  This is confirmed by the source on all things Neophylax -- The Caddisfly Genus Neophylax (Trichoptera: Uenoidae), a book that was jointly authored by R.N. Vineyard, G.B. Wiggins, H.E. Frania, and P.W. Schefter (Royal Ontario Museum, 2005).  "N. atlanta remains one of the rarest species of the genus in eastern North America." (Vineyard et.al., p. 45)  For "Distribution" they note, "Neophylax adults have been collected near small streams in the foothills of the Appalachian Mountains in the southeastern United States from Virginia to Alabama."

I'll approach this ID first in a negative then in a positive way.  First, have a look at this microscope shot of one of the larvae, noting the clavate ventral gills and the dark head and legs.

1. Process of Elimination.  Of the 9 species of Neophylax described by Steven Beaty (pp. 86-87), only 5 -- N. atlanta, N. oligius, N. consimilis, N. mitchelli, and N. ornatus -- have clavate ventral gills, so we know where to begin.  We can eliminate oligius and consimilis since our larva has no markings at all on its head/face.  N. oligius, you'll recall, has a well defined yellow-orange stripe...

and N. consimilis has one or two pale spots which sometimes merge to form a short stripe.

The head/face of our larva is uniformly dark brown/black.  We can also rule out mitchelli.  Mitchelli has a very distinct tubercle on top of its head --

nothing like that on our larva.   There may be a low rounded frontoclypeal tubercle on our larva, but Beaty assures me that such a "bump" is common on Neophylax.

So our larva is N. atlanta or N. ornatus.  Vineyard, et.al. note that "the larva of N. ornatus is similar to that of N. atlanta," (p. 62) but they describe the head as "yellow to yellowish brown" (p. 10) which is not at all true of our larva.  Also, they note that Neophylax ornatus is restricted to springs and small first-order streams." (p. 63)  The Rapidan is no longer a first-order stream where these larvae were found.  So, the "process of elimination" seems to point to Neophylax atlanta.
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2. Larval Description.  But what is the larval description of N. atlanta?  Can we see the anatomical features we need to see for that ID?  Two of those features are easy to see: our larva has ventral gills and it does not have a "frontoclypeal tubercle" (Vineyard et.al., p. 45).  But there are five other features that require some microscope work.    (For the detailed larval description, see Vineyard, et.al., p. 45).

1. There is "a relatively large number of long prontoal setae."  Yes.

2. We should see "about 4 setae" at the sa3 position of abdominal segment 1.  I think I can see 5 on this larva -- probably close enough.

3. There are "lateral gills" at 2p and 3a -- i.e. on the posterior (p) edge of abdominal segment 2 and the anterior (a) edge of segment 3.  They're difficult to see...but they're there.  Look closely; the tips overlap.

4.  And now for the toughy, which apparently is a critical feature.  Ugh!  There is a "spiculate microsculpture on the pronotum," (p. 45), i.e. it looks "grainy" or "cobbled."  I can see it with my microscope.  This is the best I could do with my photos.

When all of this evidence is taken together, I think Neophylax atlanta is a pretty safe bet for our ID.  I've added this taxon to our EPT list.
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Photos from the Rapidan River: 12/15/13

Just a spectacular insect: the spiny crawler mayfly, Ephemerella subvaria, beloved by fly fishermen for providing the "Hendrickson" hatch.  The Rapidan remains the only place that I've found it, but then Beaty notes that it's "mountains only," and "rare."  (No tolerance value has been assigned.)

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I'll just post some photos today -- but I'll have more to say on this trip in a follow-up entry.  Why?  Because I found some Uenoids that I've not yet pinned down.  They could be Neophylax atlanta -- a species that's noted as "rare" -- but I need to look at them closely and study my sources.

Dark heads -- no yellow/red spots or stripes, no obvious "tubercle" on the heads, and they do have clavate ventral gills.  More later.
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The most common insect I saw today -- the pronggilled mayfly, genus Paraleptophlebia, but I didn't get any good photos!  So we move on ----

1. Large winter stonefly, Taeniopteryx burksi-maura.  This is the most mature nymph of the species I've seen so far this season.  Note the way the back wing pads flare out from the body.

2. Perlodid stonefly, Isoperla montana.  They're already showing their "stripes" (common name: "striped tails").

3. Giant stonefly, Pteronarcys proteus.  Lovely pattern on the pronotum and wing pads.

3. Lepidostomatidae (Scaly-mouth caddisfly), genus Lepidostoma.  There were a lot of them in the leaf packs.  I photographed two.

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And then there was this critter that didn't qualify as being "aquatic"!

Color at last: mature small winter stoneflies, Allocapnia pygmaea

Not exactly the morning I had in mind.  My destination was Buck Mt. Creek, but the water there was high and off-color.  True, we've had a lot of rain in the last 3-4 days -- still I was surprised. But I thought a small stream would be safe and headed to the Whippoorwill Branch of the Mechums.

This is a good stream for Uenoids -- and I found some -- but I saw a lot of small winter stoneflies in the leaf packs that were fairly mature, like the one in the photo above.  Another look.

Like most of the insects we see, the small winter stoneflies don't show off their colors until they reach these final stages.   Based on the work that I've done, I'd conclude that this is Allocapnia pygmaea, a very common small winter species.  For a detailed discussion of the features that lead us to this identification, look back to the posting of 11/4/12.  Here I'll just mention three points.  1) According to Harper & Hynes, A. pygmaea nymphs range from 6 -- 7.5 mm.  This nymph was 6 mm almost exactly.  2) Mature male A. pygmaeas have a long supraanal lobe, around twice the length of tergite 10.  And 3) On mature nymphs there is transverse banding on the abdominal terga.  Features 2 and 3 are both clear in the following photo.

We need the male nymph for exact identification, but I also found a female A. pygmaea today.  Note the difference in the supraanal lobe.  Also, the female abdomen -- and I've observed this before -- seems to be wider than that of the male.

We should see more and more mature small winter stoneflies through December and January and into February as well.
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But I was after Uenoids since I've never ID'd those that live in this stream to the level of species. The rocks were covered with Glossosomatids (Saddle case-makers), but I finally found some Uenoids.  I took photos of two, and both were Neophylax oligius, which, says Beaty, is the "most common Neophylax in NC."  (Beaty, "The Trichoptera of North Carolina," p. 87)

#1

#2

The faces give them away -- but let's review Beaty's description.  "N. oligius -- well developed clavate ventral gill on abdominal segment 1; yellow stripe on head, but varies, should be greater than 1/2 head length...underside of head usually testaceous."  (Beaty, p. 87)

The yellow stripes here are clearly greater than 1/2 the length of the head, and the undersides of the heads are indeed "testaceous" (reddish-brown or brownish-yellow).

For the "clavate ventral gills" we need a microscope view.  (clavate = narrow at the base and thick at the top: club-like)

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Finally a nice morning after a dark, dreary stretch.  Hope to get out again on Friday.  Might see more of these stoneflies.