Tuesday, October 29, 2013

A new stream -- and possibly a new Strong-case maker: Psilotreta frontalis


This morning, my friend with all sorts of connections -- ahem! -- got us invited to look at a new stream at Montfair Resort Farm (http://www.montfairresortfarm.com/) a beautiful place to vacation and hike in the hills above the Doyles River.   We had a number of streams from which we could choose, so we hiked down to a small one -- remote -- that empties into a pond.

This turned out to be a very small stream, low water at the moment, and there were not a whole lot of riffles.  Still, we saw plenty of insects including what for me would be a new Stong-case maker species, Psilotreta frontalis.  I'm not 100% sure of this ID, but let me lay out the evidence, such as it is,  using Beaty's "The Trichoptera of North Carolina," p. 97.

P. frontalis -- larvae up to 14 mm; coloration variable, generally a broad black stripe extending dorsally over head, sometimes wider than frontoclypeus; two light areas anteromedial to eyes extending to anterolateral corners of frontoclypeus in all but darkest specimens; dark on pro- and mesonotum confined to middle stripes and lateral edge; pronotum with anterior edge slightly darker than ground color; anterolateral pronotal projections relatively short.  Spring fed streams in Sandhills and Mountains.

We need a close-up of the head, pronotum, and mesonotum which I've tried to produce in the following photo.


1. There clearly is a broad black stripe extending over the head, and it is indeed wider than the frontoclypeus in places.

2. I really don't know about the pale areas anteromedial to the eyes.  That's where I need to do further work.

3. We can see that there are black stripes on the pro- and mesonotum in the middle and on the sides.

4. No question that the anterior edge of the pronotum is darker than the ground color.

5. And, I think the anterolateral projections on the pronotum are shorter than those that I normally see.

Compare:

a. today's larva


b. what I normally see, which I think is Psilotreta labida


So a tentative conclusion on this: the Strong-case makers that I saw today might be Psilotreta frontalis.  Whatever they were, there were a lot of them!

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As for the rest...

1. Flatheaded mayfly, Maccaffertium merririvulanum, one of the two species we normally see in small head-water streams.  Note the pale "V" marks on segments 7-9.



2. And the other flathead that we commonly see with M. merririvulanum -- Maccaffertium pudicum.


3. A tiny pronggilled mayfly, genus Paraleptophlebia


4. And a Saddle-case maker -- Glossosoma nigrior.


Saddle-case makers, because their cases are open at both ends, can reverse direction inside of their cases, with their heads sticking out at the top and then at the bottom.  Right after I took this photo, this larva ducked back into the case -- and then it popped its head out the bottom.


And then it went back to the top!


5. Oh, there were also quite a few Roach-like stoneflies around -- clearly genus Tallaperla.

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Looking forward to returning to Montfair soon to get into more of their streams.

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