Sunday, December 23, 2012

It was something about the gills: Pronggilled Mayflies -- a new genus, Leptophlebia

This entry was going to be "The Day of the Caddis" -- until I got home and realized that the pronggilled mayfly I had found at the Upper Doyles River was, for me, a new genus: Leptophlebia.  I took a lot of photos of this little nymph because the gills looked a little bit odd.  And they were.

You'll recall that almost all of the pronggilled mayflies we see are genus Paraleptophlebia.  This is one that I found at South River on 12/12.

Note that the all of the gills look the same.  Let me quote Beaty ("The Trichoptera of North Carolina," p. 40): "gill 1 similar to remaining gills in structure (usually forked with lateral tracheal branches conspicuous)."  The "forked" gills -- even the tracheation in each gill before we get to the fork -- is very clear in this photo.

Now take a close look at the gills on our nymph found this morning.

The gill on segment is small and forked: the rest are not.  The gills on segments 2-7 are "bilamellate" -- each has two thin, tracheated plates that end in a slender filament.  From Peckarsky (Freshwater Macroinvertebrates, p. 33):  Gills on segment 1 forked; remaining gills bilamellate....Leptophlebia."  In this microscope view of our nymph, you can see the simple fork on gill 1: all the rest "split" -- as it were -- into two plates which narrow down to filaments at the end.

And if we tear off one of those bilamellate gills, we see one of these.

Very cool!  I love finding new things.  Beaty lists 5 species of Leptophlebia in North Carolina.  I'll see what I can do with species ID later on, though he cautions to ID at the level of "genus".


The rest, for me, is anti-climactic, but I did find some very nice insects and got some pretty good photos.  So, off we go.

1. The flatheaded mayfly, Maccaffertium vicarium.  This species is fairly intolerant (1.5), and I've found it at this site before.  Note the dark banding on the posterior edges of the tergites and sternites.

2. Uenoid caddisfly larvae -- the rocks were covered with them.  I did not see Apataniidae at this site.  I took dorsal and ventral photos of two of the many I saw.

3. Lepidostomatid case-making larvae -- there were also a whole lot of these.  If you look closely, you can see the eyes in some of these photos.  The last photo is of a very small case that I thought was empty.  But it wasn't: you can see the little head popping out!

4. A Perlodid stonefly, Diploperla duplicata.

5. A Chloroperlid stonefly, genus Sweltsa.  Note the "hairy" wing pads, one of the traits of a Sweltsa nymph.

6. And a large winter stonefly, Taeniopteryx burksi/maura.  In the second photo you can clearly see why the coxal gills are described as "telescoping."


A final photo showing that tiny Lepidostomatid next to our pronggilled mayfly, genus Leptophlebia.

Note:   Leptophlebia has been added to the EPT lists of 9/8 and 10/1.

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