Friday, July 5, 2013

Small minnow mayflies: two stops -- five species

I decided to check out the upper Doyles River this morning -- up at Brown's Cove -- though I expected to find very little.  Up there the river is small and clean, and in the winter and spring it hosts high quality insects.  But would I find much of anything there in the summer?  Well, surprise, I found a lot of small minnow mayflies.  I've been "lookin' in all the wrong places."

1.  In the photo at the top of the page, a beautiful male Acentrella nadineae.  Beautiful pattern on the thorax/wing pads.

The female nymphs that I saw were plainer in color and pattern.

2.  A smallish Baetis flavistriga, the first one I've seen so far this summer -- but I never see very many.

For species ID, we look at the marks on the terga: "two large submedian kidney shaped spots on abdominal terga." (Beaty, "The Ephemeroptera of North Carolina," p. 6)  These.  (Note that two of the cerci are missing.)


3. Also at the upper Doyles site, a tiny Baetis intercalaris nymph.

If you look closely, you can see the parentheses marks on the terga -- () -- that distinguish this species.  Also, there is banding on the cerci at both the base and the middle.

On my way back into town, I decided to stop at my lower Doyles site, just one mile shy of White Hall.  I was hoping to find another Serratella spiny crawler.  No luck with that, but I did find two additional small minnow species.

4. Acentrella turbida.  Note the broad thorax vs. that of A. nadineae.   (And the gills do not look the same.)

5. And then I found this male Plauditus dubius nymph.

But I also found this tiny, tiny nymph.

What on earth is that one you say?  I sure didn't know until I got home and uploaded my photos.  Then I noted the following features:  1) the tails are banded medially, and 2) there are median spots on tergites 2 and 6, and 3) tergites 5-7 are slightly darker than the rest.

That makes it a "female" Plauditus dubius!

Off to the Rapidan River tomorrow where I'm bound to see lots of nice things -- though it's hard to beat this nymph for beauty.

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