Tuesday, June 26, 2012

Small Minnow Mayflies at the Moormans: Again, Both Known and Unknown

A quick trip to the Moormans on Free Union Rd. this afternoon, and I was reminded of why I don't go to streams in the afternoon in the summer: it's too difficult to get photos.  With the sun high in the sky it's virtually impossible to shoot straight down on your subject: you're always creating a shadow!  But I did find some nice insects, and lots and lots of small minnow mayflies.

But we start (the photo above) with a beautiful spiny crawler.  This is the one we see in the summer -- Serratella serratoides -- but I've never seen one before with such beautiful colors.  Another shot:

I should run through the full species description -- and I'll do that one of these days -- but the critical feature to see: "a transverse row of four black dots on each sternite; often with speckling on [the] last few sternites in some specimens" (Beaty, "The Ephemeroptera of North Carolina," p. 31).  Here you go:

I found two S. serratoides spinys today, the second was a drab brown which is the color I normally see.


And now for the small minnow mayflies.  I saw two species I recognized without any trouble -- but I have three insects that will require identification.  Fortunately, we have a boiling hot weekend in store: great time to work in my lab in the basement where it's always cool.

The two small minnows I knew: Baetis intercalaris (did not take a picture) and Heterocloeon curiosum.   I think most of the small minnows I saw were H. curiosum.  A couple of photos.

The three that will require some work are these:

1) A reddish/brown nymph -- with a leg missing.  In the first photo, it lined up next to one of the H. curiosums.

2) A beautiful nymph which posed nicely for photos.  I feel like I should know this one: the gills look like it's a Heterocloeon.

 3) A tiny, but fully mature, nymph, with hairy legs like we find on Acentrella, but it's only 3 mm long.
The larger one at the top is, again, the reddish brown nymph on which I need to work.

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