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.)

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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!
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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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