Tuesday, January 22, 2013

And to finish up that report...

This is where I was yesterday -- is it any wonder that I find wonderful insects in this kind of stream?   And I did find wonderful insects.  Within an hour, I had collected Peltoperlids (Roach-like stoneflies); Chloroperlids (Green stoneflies); Perlodids (Malirekus hastatus, Diploperla duplicata -- and others to be ID'd); Giants (P. proteus, all sorts of sizes); Leuctrids (Rolled-winged stoneflies); Pronggilled mayflies; Ameletid mayflies; and Flatheaded mayflies (Maccaffertium pudicum, Maccaffertium merririvulanum, and Epeorus pleuralis) -- and more.  And there were the Uenoids (Neophylax mitchelli -- see yesterday's posting -- and Neophylax aniqua) and the Limnephilids (Northern case-makers).

Then I slipped, tipped my bowl, and lost everything that I had collected!  So I started over again but was contented with less, deciding to focus on the case-making caddisfly larvae.

1. The Limnephilid, Pycnopsyche gentilis.

I saw a lot of them -- but this one seemed like the best subject for photos.  I'll have to check my records on this, but I think that P. gentilis is the only Northern case-maker I've seen in these small mountain streams.  In early instars, it usually makes this kind of case -- a three-sided case made out of trimly cut sections of leaves which then overlap one another.    In later instars, you may remember, they normally switch to a case made of pebbles which are firmly cemented together.   In this photo taken in May of 2011, we see a case that's in transition.

This is a sizeable insect, reaching lengths of 20-22 mm (Beaty, "The Trichoptera of North Carolina," p. 84).  But the one in yesterday's photos was about 10 mm in a case that measured 15.   The tolerance value is 1.8.  Trout, by the way, will eat them case and all!  But I've never seen any trout in this little stream.

2. Uenoid caddisfly larva, Neophylax aniqua.

For more detail on this species, look at Saturday's posting.  A friend has reminded me that it's risky to ID an immature larva, so my ID is a tentative one -- but I feel pretty certain about it.  This larva was 4-5 mm in a case that was 6.

You'll recall that the key features in this species ID are 1) the lack of clavate gills on abdominal segment 1; 2) lack of lateral gills; and 3) a stout, median frontoclypeal tubercle that does not point to the rear (like that of N. mitchelli).   If you look closely at this photo, you can see the tubercle on top of the head...

But it shows up much better in these microscope views.

In this last photo, the clavate gills are conspicuous by their absence.  I.e., you don't see these (photo of Neophylax consimilis):

In the North Carolina list of tolerance values, N. mitchelli is rated 0.0; there is no rating given for N. aniqua.   But it's probably a very intolerant insect.  Remember that it is common to find N. mitchelli and N. aniqua in the same types of streams (first order streams; headwater streams).

Just a few other photos.

3. The flatheaded mayfly, Maccaffertium merririvulanum.  I managed to find another one after dumping the first!  Note the pale "V's" on the tergites.

4. A Leuctrid that I found on Saturday but didn't bother to post.

5. And this is what the Malirekus hastatus Perlodid stoneflies will look like when I get some good photos!


Off to the Doyles River tomorrow -- if I can put up with the cold!

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