A "Really" Green "Green Stonefly": Genus Alloperla -- Super Finds at the Doyles

On my way to the stream this morning, I had already decided the title for today's entry, "Our Summer Small Minnow Mayflies," being sure I would find at least two of the species that we see in the summer -- Acentrella nadineae and Baetis intercalaris.  Wrong -- though I did find two small minnow species, about which more in a moment.  Then when I started picking up insects, I was finding the common stonefly, genus Perlesta, all over the place.  So my title would be "Our May and June common stonefly -- genus Perlesta."  And then I found this little beauty.

This is a Green stonefly, genus Alloperla -- the same Chloroperlid we found last week in a small stream in Sugar Hollow.  But those nymphs were golden brown (see the photo in the entry for 5/18); this one was green, and I do mean "green"!   If you look at the adult Alloperlas pictured at Bugguide.net (e.g., http://bugguide.net/node/view/402296), you'll see that they too are bright green in color.

I spent over an hour trying to get some good photos of this little insect, and I almost gave up.  It never slowed down, it just kept dashing around the petri dish.  And when it did pause, it would take off again before I had a chance to clearly focus!  So I tried something new: I put the nymph in a tablespoon measuring spoon (my wife's suggestion, I hasten to add), which increased the odds in my favor.  These are the best shots that I got.

I'll soon be posting an entry on Alloperla, with microscope photos showing the key features used in identification.  In the meantime, I should note that Beaty says of this genus, "Mainly collected January through May in the Mountains.  Uncommon." (Beaty, "The Plecoptera on North Carolina," p. 9)
And although I would like to ID our Alloperlas to the level of species, I don't think that's going to happen.  Beaty advises to leave these at the level of genus, and although I've found a good article with illustrations and descriptions for eight, Eastern species, the detail needed to determine species ID is simply beyond me.  (The article is Bill P. Stark & Boris C. Kondratieff, "Larvae of Eight Eastern Nearctic Alloperla Species (Plecoptera: Chloroperlidae), and it's on line at: http://www2.pms-lj.si/illiesia/papers/Illiesia07-04.pdf.)

Now on to our small minnow mayflies and the Perlestas.  As I noted I did find two species of small minnow mayflies, but they were "spring" small minnows: Acentrella turbida and Plauditus dubius.  Both species have been described in previous entries. I did get some good photos.

Plauditus dubius, female:

Plauditus dubius, male:

Acentrella turbida, female:

Remember that the tails on P. dubius are "banded" -- not so on A. turbida -- but A. turbida has the very broad thorax.

I'll give short shrift to what I thought might be my main topic: the common stonefly, genus Perlesta,
except to say that I never expected to see so many so close to being mature at this early date, and the one in the photos below is already ready to hatch.  I'll pay more time on this insect in June -- we'll be seeing them in almost all of our streams -- and at that time, I'll pay more attention to genus and species ID.

One more insect that I was happy to find: a spiny crawler mayfly, genus Serratella.  The "spring" spiny crawlers -- Ephemerella dorothea -- are virtually gone: while we saw that species in huge numbers, Serratella serratoides is a species we only see on occasion.  Unfortunately, my live shots of this nymph did not turn out very well, so we'll have to settle for a microscope view.

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A final look at our Alloperla Chloroperlid.

Moving into Leuctrid (Rolled-winged stonefly) Season

Last week when I picked up the Alloperla Chloroperlids (genus Alloperla, Green stoneflies) in Sugar Hollow, I was sure I had picked up some Leuctrids: today I went looking for more Alloperlas -- and thought that I had them -- they all turned out to be Leuctrids!!!  (Both nymphs have long, thin, abdomens that are essentially parallel sided.)

But we're moving into their season and can expect to see more and more nymphs, some might be fully mature.  I found this one today -- badly mangled -- but you can see how the wing pads had already turned black.

Beaty reports that there are three genera of Rolled-winged stoneflies found in his state -- Leuctra, Megaleuctra, and Paraleuctra --but by far, the most common is Leuctra (Beaty, "The Plecoptera of North Carolina," p. 2).  In central Virginia, Leuctra is the only genus to date that I've seen.  They are easily ID'd -- well, using a microscope that is -- by the fact that the labial palps extend past the rest of the labium.  (Sorry, thought I had a photo of that -- but I'll take one next time around).

The sun was again giving me fits today when I was trying to get my photos.  Still, I managed a few nice photos of one of these nymphs.

Our Leuctrid nymphs are now large enough that their characteristic wing pads are easy to see: both front and rear wing pads are "finger-like," and the front wing pads are wider than the abdomen, while the rear pads lie on top of the first abdominal segments.

Beaty says that some Lecutrids are found in "larger rivers": I've only seen them in very small streams.

Not much else to report on today -- it was a very quick trip since there were threatening skies.  But I did find plenty of the "other" nymphs that have moved into their season as well: the Perlodid stoneflies, Remenus Bilobatus and Isoperla holochlora.

R. bilobatus

I. holochlora

Nothing New at South River -- But Quite an Assortment of Insects

I found nothing new at South River this morning, but I did see a whole lot of insects, most with pretty long wing pads -- i.e. getting ready to hatch.

Mayflies: There were still quite a few spiny crawlers around - E. dorothea -- though nothing like the numbers I saw the last time I was here.  The one that caught my eye was this lovely genus Eurylophella, probably Eurylophella verisimilis.  I'm still fascinated by those large, operculate gills on tergite 4 -- sticking out to the sides on this male -- that cover, and protect, the gills on tergites 5-7. They're somewhat tolerant, obviously because they're not bothered by crawling in silt!  (I only rarely see a clean one.)

2. I also saw a fair number of brushlegged mayflies (Isonychia bicolor).  They were big -- but the wing pads were quite a bit shorter than those on the nymphs I saw at the Rapidan River.

3. Pronggilled mayflies (genus Paraleptophlebia):  Actually, I only found one.  I wasn't surprised to that they're in here, this is the habitat that they prefer (clean, cold, mountain stream).   But this is the first one I've seen in this river.

4. Epeorus pleuralis flatheaded mayflies.  The bottoms of rocks were still covered with these nymphs up here.  I'm surprised to see them around this late in the spring, but, the wing pads show that they'll be taking off -- literally! -- very soon now.

Stoneflies:  I saw two common stoneflies (Perlids) -- a large one that will be hatching soon and a small one that will be hatching next year.  But I saw large numbers of two different species: Isoperla holochlora and Remenus bilobatus.

I. holochlora -- normal color:

I. holochlora -- one that's unusually yellow:

Remenus bilobatus: I photographed two of the many I saw -- both were fairly mature, and the one had dark markings showing up on the wing pads.

Caddisflies: Saw a few fingernet larvae, genus Dolophilodes, and a couple of freeliving caddisfly larvae, both R. fuscula.  But what did I see in large numbers?  Glossossomatids (Saddle-case makers)!

Time for me to read up on this caddisfly family.  I always see them in the winter, but here they are once again in late spring.  In the photo above, you can see the larva's front legs sticking out of the case.  But I got some good photos of the larva moving to get out of its case once its "dome" had flipped over.  (It never did leave its case, by the way, and it's now safely back in the river.)

On the Chloroperlid Found Yesterday: Tentative ID -- genus Alloperla

I've done my best to identify this Chloroperlid I found yesterday (I found at least 2 of them) to the level of genus: I'm not at all certain that I've succeeded.  But I'm happy to share the evidence that I've assembled.
I plan to keep working on this and hope to find another, more mature, specimen in the near future.

I have consulted five sources in doing this work, from which I will cite on occasion.  They are:

1. Barbara Peckarsky, et.al., Freshwater Macroinvertebrates of Northeastern North America, p. 73)
2. Steven Beaty, "The Plecoptera of North Carolina," pp. 9-10.
3. Bill P. Stark and Brian J. Armitage (Editors), Stoneflies (Plecoptera) of Eastern North America, Volume II: Chloroperlidae, Perlidae, and Perlodidae, pp. 2-3.
4. R.W. Merritt, K.W. Cummins, and M.B. Berg, An Introduction to the Aquatic Insects of North America, Fourth Edition, pp. 326-330.
5. Kenneth W. Stewart & Bill P. Stark, Nymphs of North American Stonefly Genera (Plecoptera), pp. 247-290.

Let me start with some additional photos of our nymph, and then look at parts of the anatomy that are important in making identification.

1) A close-up of the wing pads:

2) Two close-ups of the pronotum (note setae on anterior corners):

3) A close-up of the thoracic sterna (i.e. ventral view of "chest"):

4) A close-up of the lacinia:

5) And a close-up -- but not a very good photo -- of the cerci (tails):

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Steven Beaty lists the following Chloroperlid genera from which we can choose: Alloperla, Haploperla, Rasvena, Suwallia, and Sweltsa.  Peckarsky adds Utaperla, but Utaperla has not been attested in NC or VA (Stewart and Stark, p. 290).

Let me begin by eliminating some of those options.  This nymph is not:

1. Haploperla -- because the hind wing pads diverge from the central axis of the body: the hind wing pads on Haploperla are parallel or subparallel to the body axis.  They look like this:

2. Utaperla -- not only because that genus is not attested in the state of Virginia, but also because there are about 25 segments on Utaperla cerci (Stark and Armitage, p. 2): the number of segments on the tails of our nymph is 12.

3. Rasvena -- because mature Rasvena nymphs are less that 5.5 mm in length (Beaty) while our nymph is about 7 mm.  Also, there are 4 longitudinal stripes on the tergites of Rasvena, not on the nymph in our photo.

4. Suwallia -- because Suwallia nymphs are 8 - 10 mm in length.  (But this is an option I may need to reconsider.)

That would leave us with Alloperla or Sweltsa.  Sweltsa is the Chloroperlid we've been seeing all winter: most Sweltsa nymphs have already hatched.  This is a photo of Sweltsa:

This does not look like the nymph that I found yesterday.  Look at the abdomen: short and wide, bulging a bit in the middle; now look at the abdomen of the nymph pictured at the top of the page.  It's long and thin.  Here's a microscope view of the two nymphs side-by-side: Sweltsa on the right, new nymph on the left:

The abdomens are strikingly different; so too are the heads in terms of their shapes.  Here's another, closer view:

Something else -- Sweltsa nymphs are very hairy: the wing pads are hairy, the tergites are hairy, and, you may recall, there are "thick depressed black clothing hairs laterally on all thoracic sterna," (Beaty) as in the photo below.

Compare that "chest" with the one of our nymph in the earlier picture.

So the "negative" approach leads me to Alloperla.  But, on the positive side, what do our keys say about Alloperla?  I'll use Peckarsky for this.

Peckarsky (p. 73): "Pronotum with few or no setae on front and, especially, hind margins; setae present only on corners."

I think that's correct for our nymph: I see no setae on the front and hind margins.

Peckarsky continues: "apical 7-10 cercal segments with numerous vertical long setae between apical coronas forming a feathery fringe visible in lateral view."


I'm not sure about this.  I am not sure if there are "long setae between [the] apical coronas forming a feathery fringe."  Part of the problem is -- and I've tried and tried -- I cannot turn my nymph so that I can get a lateral view of the final cercal segments!

She adds: "setae absent on 8th tergite at mesal posterior margin; integument gold-brown."


This is the best view I can get of the 8th sternite, and I can't tell for sure if there are setae in the middle part of the sternite or not.

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So, when all is said and done, I'm not sure where I stand on the ID of this "new" Chloroperlid.  I feel strongly that it is not, in terms of the genus, Haploperla, Utaperla, Rasvena, or Sweltsa.  If pushed to decide an ID, I'd stick with Alloperla.  But I think I still need to look more at Suwallia nymphs.  What I need is more specimens on which key features will show up a bit better.

Later note: The illustrations of Chloroperlid pronotums in Stewart and Stark lend support for an Alloperla ID.   Almost all other Chloroperlid genera -- including Sweltsa and Suwallia -- have visible setae on the anterior and posterior margins.  See pp. 255, 279, and 282.

Also note Tom Murray's images of Alloperla at: http://bugguide.net/node/view/264459/bgimage.