Friday, December 30, 2016

The other small winter stonefly -- Paracapnia angulata

Genus Allocapnia small winter stoneflies are common and plentiful in all of the streams that I visit: this genus isn't.  This is the third or fourth time that I've seen it, and I've only seen it in two small streams in Sugar Hollow.  These.

This is genus Paracapnia, species angulata.  Too uncommon to have a tolerance value assigned.

The keys to identification are: 1) the entire body which is very setose - hairy- as in the photo above, 2) the shape of the wing pads, and 3) the complex pattern on the head.

On the wing pads -- the posterior ends of both pairs are rounded (the rear pads of Allocapnia are truncate).  Paracapnia wing pads look like this.

But let's look at Beaty's description ("The Plecoptera of North Carolina," p. 8) before we go any further.

Genus Diagnosis: Nymphs 6-8 mm.  Head with a purplish-brown reticulate color pattern; pronotum fringed with many long bristle-like hairs, longest at corners; body setose, with numerous long setae.

angulata -- Head pattern of purplish pigmentation outlining entire frontoclypeus, with a short bar from median ocellus to the anterior edge of the frontoclypeus; occiput usually with purplish bars along,  but removed from epicranial stem to postocciptal margin.

The purplish brown pattern is clear from our live shots.

But for the detailed features of the head and pronotum it's best to use a microscope photo.

We should also note that if we find a Paracapnia nymph in our parts, we've found P. angulata since Beaty notes that "Paracapnia angulata is the only known species of Paracapnia in the southeastern United States." (p. 9)


Actually, the reason I went out this morning -- it was cold and blustery -- was to look around for more Uenoids (little northern casemakers).  And I found them of course since they're plentiful at this time of year.  This morning it was  Neophylax consimilis.

In terms of the "longitudinal gradient" (see the entry posted on 12/15),  this one occurs -- in my experience at least -- between N. aniqua and N. mitchelli (further upstream) -- and N. fuscus and N. oligius further down.  (N. mitchelli has a TV of 0.0; N. consimilis is 0.3; N. oligius is 2.4.)

N. consimilis does not have a tubercle on the head, but it does have clavate gills on the first abdominal segment.  The setae count at sa3 (ventral) is 2-3.  Here you go.

On occasion consimilis has a frontoclypeal pale spot  -- like this

-- but in other cases the head is totally brown.  Such was the case on the one that I found this morning.


Good fun, even in freezing weather.

Friday, December 23, 2016

Perlodid stonefly Malirekus hastatus in a VERY small stream in Sugar Hollow

On Wednesday I went to a very small stream in Sugar Hollow, probably the smallest stream that I visit.

The water, as you can see, was low, and I despaired of finding anything at all.  I was hoping to find some Uenoids, hoping to find N. ornatus, but I didn't see a single case.  I was also hoping to find that little casemaker that I found here at the start of last year -- Adicrophleps hitchcocki.

No luck.  What I did see in fairly good numbers was a Perlodid stonefly that is fairly common in Sugar Hollow in the winter -- Malirekus hastatus.  Beaty notes that these nymphs are "typically collected from small mountain streams and rivers."  He also notes that they're "predators -- engulfers."  ("The Plecoptera of North Carolina," p. 71)  I'd say that's an understatement.  They're vicious.  You cannot leave a mayfly with them in the same bowl.  Turn your head and that mayfly is gone -- engulfed!  If you want to collect them, do like I do and carry two bowls.

Here's Beaty's genus description.  "Lacinia with low marginal knob bearing a tuft of setae and ventral surface with a cluster of approximately 50 clothing hairs near base; labrum concolorous; head brown with distinct, completely enclosed pale M-pattern; pair of linear spots anterior to M-pattern; large suboval pale spots lateral to ocellar triangle; a faint ocellar spot present; occiput with large oval areas with brown reticulations, enclosed posterior by dark band and occipital setal row, a mostly single, irregular curved row of closely set spinules on back of head, obsolete near midline." (p. 71)

All of that looks like this.

On the species -- hastatus -- he adds: "Conical submental gills ... abdomen brown and often with a pair of pale submedial dots, some specimens with pale lateral dots and an obscure longitudinal, slightly darkened stripe between pale submedial dots."

You can see the abdomen markings in the photo above.  For the submental gills, they look like this.

I think I've commented before on the large heads on small nymphs like this one.  By February they change.

Thursday, December 22, 2016

The "Appalachian Springfly" -- Isogenoides hansoni

Of the many "rare" and "uncommon" taxa that I find at the Rapidan River, this may be the one I like best.  It was one of the things I was hoping to see this morning and I lucked out.

The features noted as critical of the genus ID by Steven Beaty are these: "...mesosternum with median longitudinal suture joining fork of mesosternal grooves to transverse anterior suture; prominent submental gills, projecting about three times their basal width."  ("The Plecoptera of North Carolina," p. 57)  Here you go.

(Look closely, the median line is hard to see.)

On the species ID he says this:  "nymphs 16-24 mm.  Head with conspicuous, sharply delineated pale M-pattern anterior to median ocellus; ocellar triangle bordered by dark brown but with pale, ovalized central spot; occiput brown anteriorly with light brown reticulated areas enclosed by spinule row...; pronotum widely margined with brown."

Very clear.

Isogenoides hansoni, the "Appalachian Springfly".


The Rapidan water levels are great at the moment, and there are lots of good leafpacks around, all loaded with Pronggilled mayfly nymphs.  But there were other things that provided good photos.

1. Giant stonefly, Pteronarcys biloba (the "Knobbed salmonfly")

This beauty measured 34 mm!  I had to get up on my knees to get a photo of the whole nymph.


2. And again one of those "ho-hum" -- gorgeous! -- spiny crawlers. Ephemerella subvaria.


3. A very small common stonefly, Agnetina capitata.  I saw a number of A. capitatas that were quite a bit larger than this.


3. A couple of shy Lepidostomatids, one young one with a "mixed media" case.


4. And a "humpless casemaker" -- Brachycentrus appalachia -- with a young Isoperla montana nymph hitching a ride.  (First I. montana nymph of the season.)

The Rapidan River in winter

Thursday, December 15, 2016

The Uenoids (little northern case-makers) at Buck Mt. Creek: at the bottom on the "longitudinal gradient"

At Buck Mt. Creek yesterday I collected a couple of Uenoids to photograph.  I assumed they would be the same species: that turned out to be wrong.

Let's start with the larva at the top of the page.  It's been awhile since I worked on Uenoid identification, but I still remembered the key features we have to examine.  They are: 1) the presence or absence of a tubercle on top of the head (also it's size and shape if present); 2) the presence or absence of "clavate" gills; and 3) the number of setae at the sa3 position on the first abdominal segment (ventral).  E.g.,

This larva lacked clavate gills, and I did not see a tubercle.  The setae count at sa3 came to 6-10.  Here's the view.  Note that they're also long and thick.

Of the species I've found so far in our streams, that sounded like Neophylax fuscus.  (See R.N. Vineyard,, The Caddisfly Genus Neophylax, Royal Ontario Museum, 2005, p. 24.  "Frontoclypeus lacking median tubercle,""Abdominal segment I with ventral sa3 bearing 6-9 relatively long stout setae; segment I lacking [clavate] gills.")  Sounds like a match, so I looked to Steven Beaty for confirmation.  There we find "N. fuscus -- without clavate ventral gills on abdominal segment 1; large blade-like spines on anterior pronotum; head dark brown to black with light muscle scars.  Occurs in northeastern Mountains and clean headwater streams to the Tar River. ... Relatively rare." ("The Trichoptera of North Carolina," p. 87)  I was unable to get a good view of the front of the pronotum, but the muscle scars on the head were easy to see.

I feel pretty good with that ID: Neophylax fuscus.

How about number two?

With the microscope I could see that this larva too lacked clavate gills, and I couldn't see any tubercle.  I thought it was just the same species.  But then I counted the setae at sa3 -- only 4.

That takes fuscus out the running.   My next guess was concinnus, and I think that's what it turned out to be.  Beaty says very little about N. concinnus: it has yet to be found in NC.   For the full description -- more than I'm going to cite -- we go to Vineyard, (p. 46) where we read, "Abdominal segment I with ventral sa3 each bearing 2 to 4 setae, segment I lacking gills."   They add "Head relatively uniform in colour."  And they also say "Frontoclypeus often with short median tubercle."  The tubercle is indeed short: I didn't see it until I turned the larva the right way.

Now, I've found N. fuscus at this location before (see the entry of 12/27/13), along with N. oligius -- this one.

So with N. concinnus we now have three different species in the same spot in the same stream.  This is very interesting in terms of what the authors of The Caddisfly Genus Neophylax call the "longitudinal gradient of species" (p. 24).  Of N. fuscus they note that "it always occupies the farthest downstream zone in the longitudinal gradient of species."  I've talked about this Uneoid sequence before (12/28/13) so let me just cite my own words.

"1. Neophylax aniqua
 2. Neophylax mitchelli
 3. Neophylax consimilis
 4. Neophylax oligius
 5. Neophylax fuscus

That sequence, as it turns out, corresponds to the Uenoid continuum that I've noted so far in our streams.  That is to say -- as you move downstream from a headwater stream to a second or third order stream, you might find Uenoids all the way down, but you'll find different species.  Thus, when I go to my favorite small mountain stream in Sugar Hollow -- a first-order, headwater stream -- and go to the highest part of that stream, I find N. aniqua and N. mitchelli.  When I move down that stream to a site not far from the Moormans, I find N. mitchelli and N. consimilis.  When I go to the South River up in Greene county, the Rapidan in Madison County, and the upper Doyles River, all second-order streams, but streams that are still in the mountains, I find only N. consimilis.  And when I go to the lower Doyles River and Buck Mt. Creek, second order streams that have moved out of the mountains and into field country, I find N. oligius and N. fuscus."

When I wrote this, I had not yet found N. concinnus.  But I did find one just a few weeks after that (1/9/14).  This is a species we'd expect to find between our upstream species (aniqua, mitchelli, consimilis) and those further down (oligius and fuscus).  But I'm not at all surprised that we've found it in Buck Mt. Creek.  Of N. concinnus, Vineyard note "Neophylax concinnus occupies a wider array of habitats than any other single species in the genus, ranging from small springs and cold headwater streams to warm medium-sized rivers.  It is generally found in small second- and third-order streams."  Bingo!  That's Buck Mt. Creek.  (Our location in springtime.)


I'll be looking closely at our Uenoids this year.  I'd really like to find a species we've not found so far: N. ornatus, a species that "occurs in 1st order Mountain and Piedmont streams".  (Beaty, "The Trichoptera of North Carolina," p. 87)  It has been found in Virginia -- the Blue Ridge Mountains in Nelson and Madison counties.  No reason it shouldn't be in Albemarle county as well.

Wednesday, December 14, 2016

A review of the large winter stone flies (Taeniopterygidae)

Went out to Buck Mt. Creek this morning where I found the first Uenoidae (little northern case-makers) of the season, about which I'll post something tomorrow.  But I also found some large winter stoneflies -- pictured above -- the species we see in a lot of our streams, Taeniopteryx burksi (or possibly maura).   And this is when we see them, from November through January, with a few around in February as well.  With a TV of 6.6, it's a tolerant insect, but it's still a beauty.

With the brown body and the pale medial stripe that runs from the head to the tails, it's easy to spot, and if there's any doubt in your mind about what you've found, flip the nymph onto its back.  There'll you'll see these.

Long telescopic coxal gills at the base of each of the legs -- to me they look like bean sprouts.

While T. burksi is the most common large winter we find in our streams, it's not the only one you're likely to see if you're out there monitoring streams.  And in the very same streams where T. burksi/maura hangs you'll probably run into this one,

which is Strophopteryx fasciata.  Different colors with a mottled appearance on the head, pronotum and wing pads, and banding on the terga.  No coxal gills -- so don't rely on that feature to identify all large winter stoneflies.    One of the keys to the S. fasciata ID is the abdominal banding.  On each tergite there is a dark anterior band and a medial row of dark dots.

Also important is the ventro-apical plate which when looked at head on looks like this.

That last point is important since it's an important way to distinguish Strophopteryx nymphs from the third species of large winter stonefly we find in our streams -- Taenionema atlanticum.

Apparently there are Strophopteryx nymphs that like T. atlanticum, are uniformly brown in color (though I've never seen them).  That's why it's important to look at the ventro-apical plate.   And while the Strophopteryx plate has concave shaped sides, those of Taenionema curve straight down to a point.

But I don't think you'll find T. atlanticum nymphs where you find our other two species.  T. atlanticum only occurs in high quality, cold water streams -- like the headwater streams in Sugar Hollow that I go to -- where I've never seen T. burksi/maura or S. fasciata.

A look at some Uneoids tomorrow.