Friday, May 8, 2015

The Perlodid stonefly Remenus bilobatus in a stream where I've not seen it before

As you will see in a minute, it was one of those days when the pictures I took of the stream (small stream in Sugar Hollow) were better than those that I took of the insects.  But... first things first.

This is a Perlodid stonefly, Remenus bilobatus, one that I don't see very often.  Before this, I've only seen it in Buck Mt. Creek and the Rapidan River.  It is not a very colorful insect: "habitus brown, without conspicuous markings" (Beaty, "The Plecoptera of North Carolina," p. 26).  Though, like all of our stoneflies, they look better and better as they mature.  The photo below was taken on 5/24/13 at the Rapidan River.

But with a Tolerance Value of 0.9, there's no reason it shouldn't be found in these small mountain streams.  This is the stream that I went to today.

Remenus is a genus that has a feature that's very distinct: the lacinia has only one tooth.  Easy to see in this microscope photo.

But there's another feature that allows us to know what it is with just from a look through the camera: the bases of the maxillary palpi stick out from the side of the head, beyond the lateral edges of the eyes.

It's one of the last Perlodids to appear in our streams, and right on cue, I normally find it in May and June.

I only photographed one other insect,a young Isoperla that, like Remenus, is a late bloomer appearing in April through June -- Isoperla holochlora.  We'll see a lot of them later this month: it's fairly common in the streams that I visit.


Not the best photos, not the best of conditions.  It was hot and humid -- as you can see from the condensation on the base of my dish -- and the sunshine was a little bit hazy.

But what a stream to explore!

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