Thursday, November 3, 2011

"Success Through Perseverance": Finding Large Winter Stoneflies (Taeniopterygidae)

I think I said that by the end of this week I'd have pictures of Large Winter Stoneflies (Taeniopterygidae), and sure enough, I got some this morning at Buck Mt. Creek.  It took me awhile.  I didn't find any in the first riffle in which I looked.  I thought about giving it up, but decided to try one other riffle -- and there they were!

This is the first large winter stonefly genus we find in our streams -- Taeniopteryx.  There are several features that give this away.  For one thing, the color pattern's unique.  At this stage of the game, the eyes appear to be red, and there's a well defined light colored "Y" on the top of the head.  This "Y" connects with a light colored stripe that runs from the head to the tails in mature nymphs; but even at this size, that light stripe is starting to show.  However, the only "safe" thing to use to ID this large winter genus are the "coxal gills," long, finger-like gills that stick out from the base of each leg.  This large winter nymph very kindly flipped on its back for me to get a good look at those gills.

And here's a microscope close-up of the gills at the base of the rear pair of legs.  You can see from this photo why they're called "telescoping" gills.

These gills are normally visible using a loupe when you're out in the field.    Another look at this nymph (I wish my photos were better, but these were very "small" large winters, less than 5mm long.)

But I was in for another treat on my trip to the stream.  I found a small Perlodid stonefly, genus Helopicus.

This is a genus of Perlodid stonefly that I encountered for the very first time at Buck Mt. Creek on April 2nd this spring (see the entry posted that day).  It delighted me then; it delights me now.  For a microscope look at the key anatomical features defining this genus, take a look at that earlier entry.  But, the dark band (mask?) that runs between the two eyes is one of the things that we look for.  In April, it will look something like this.

The other thing to report from my adventure today -- the Small Winter Stoneflies (Capniidae) -- look back to the entry posted on 10/25 -- are really starting to grow.   Here are a couple of photos taken today.

and a "double"

Note how the colors are starting to change/darken, and distinct patterns are showing up -- on these nymphs at least -- on the thorax and head.  But the big change that we see -- and you can notice this when they're swimming around in your trays -- is the development that has occurred with the wing pads.  They are much bigger, and the front wing pads have lengthened.  This should be clear from the live photos: if not, here is a microscope photo to use.

Small winter stoneflies develop rapidly, and many will hatch in December, if not by the end of this month.

One final find -- an Acentrella turbida small minnow mayfly.  Note the dark wing pads on this one.  I suspect that we'll find fewer and fewer of these as the month proceeds.


The number of viewers using this blog has skyrocketed during the last couple of weeks.  So, I suspect that we have some new viewers.  For anyone reading along who would like to see more of my photos, they are posted on "Flickr" at:
Open the folder, "live photos only".

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