Tuesday, May 31, 2011

The Genus Remenus: Yet Another Perlodid Stonefly

Back from vacation -- time to get back to...well, it's not really work: too much fun!

I went to Buck Mt. Creek this morning to look for bugs in the heat (92 degrees!), and I found a real assortment.  I wasn't sure what to call this entry, but I felt that a new genus deserved its own headline.
Perlodid stonefly; genus, Remenus.  I've never seen this one before.  The distinguishing features are: 1) no submental gills; 2) the "mesosternal" ridge is shaped like a "Y"; and 3) the lacinia terminates in a single tooth (this sets it apart from the genera Diploperla, Isoperla, and Clioperla).  Here's what that looks like:

This is not the only Perlodid genus I found today.  I continue to find Isoperla holochloras.  This one -- rather light in color:

and this one -- much darker.  Note that although the Isoperla "abdominal banding" seems to be missing in the photo below, it was clearly visible when I looked at this nymph with the scope.

On the genus Remenus, I might add that it strikes me as very unique in appearance.  It is uniformly orange in color and lacking in pattern (save for a few marks on the head), and the head seems out of proportion to the rest of the body.  Look at this picture where the Remenus nymph is right next to an Isoperla in my tray.

The insects I found, for which I will not provide photos include: water penny beetles, Dryopid beetles, riffle beetles (adults), flatheaded mayflies (Epeorus, Maccaffertium, and Leucrocuta), and small minnow mayflies (genus Acentrella).   What I did not find -- spiny crawler mayflies, genus Ephemerella!!!  Not a one.  And just a few weeks ago that was the dominant taxon in all of the sampling that I was doing.  Pretty amazing.  Of course that does not mean they have all hatched in other streams (or in this one, for that matter).

I did find three other insects which deserve to be pictured.  First, I did find one lonely spiny crawler mayfly, but it was genus Drunella, and it was HUGE (1/2 -- 3/4" long).  It was clearly close to hatching.  Note the black wing pads; also note the prominent "tubercles" on the leading edge of the fore femoras, a defining trait for this genus.

Second, I found a Ceratopogonidae ("biting midge," "no-see-um"), and I was actually able to get a pretty good picture (they're very small).   Cerats differ from the common midges we see (Chironomids) in a number of ways.  They are longer and thinner than "normal" midges; they are "zebra-like" in color pattern; they have pointed heads; and they do not have prolegs in the front or the back.  (For a good picture of a "Chironomid" midge, see the entry for 3/2/11.)  Click on the photo below for a better view.

Finally, I finally found a dragonfly: it was a Darner (family Aeshnidae).  I've been expecting to see dragonfly nymphs, and there were a number of adult terrestrials flitting around in the tall grasses that border the stream.  Darner dragonflies are normally dark brown to black in color, with long tapered bodies.  Also, you will often find them -- as I did with this one today -- in leaf packs close to the shore.

Not very pretty -- but then, not everything can look like a Perlodid stonefly!  It's good to be back, and readers can expect a steady supply of new entries now that the summer's begun.

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