Friday, November 29, 2013

Fairly certain I'd see the case-maker Apatania incerta at the Doyles River this morning

No, that isn't Apatania -- but it's a very nice look at the Perlodid stonefly, Diploperla duplicata.  I saw a number of them this morning -- by far, the largest Diploperlas I've seen this season.


But I found, for the first time this season, several "little mountain casemakers" -- family, Apataniide.

This was a very small larva.  The case was less than 4 mm in length; the larva went about 3.  Still, the distinguishing features were clear: case of small pebbles and sand grains, tapered, cornucopia shaped with a hood; larval body yellow; no sclerites at the sa1 position on the metanotum.  And as I noted in the last entry, the hooded case covers the head of the larva when it's crawling around, but you can often see the legs sticking out to the side.

Also clear in this sample, the larvae sometimes add larger pebbles/crystals to the hood of the case.

I think it's safe to call the larvae I find Apatania incerta.  But I should note that Beaty cautions to leave our ID at the level of genus -- Apatania -- which, notes Thomas Ames, is "the most common eastern species, with a range as far south as the southern highlands.  (Thomas Ames, Caddisflies, p. 229.)  A. incerta is described by Beaty, in fact it's the only larva that he describes, and that description matches our larva.  Also, he notes that two other secies -- A. pravaelens and A. rossi -- have been synonymized with A. incerta (Flint, 2007).  But that synonymy has not yet been accepted in with the World Trichoptera Checklist.  (Beaty, "The Trichoptera of North Carolina," p. 85)  So, it's genus Apatania if we want to be cautious; species Apatania incerta if we add these qualifications.

In any event, I found them in the Doyles last year, and at the Rapidan, and in some smaller streams as I recall.  The tolerance value is only 0.6.

Other photos:

1. A large winter stonefly, Taeniopteryx burksi/maura.  Note the "coxal gills" in the second photo.

2. And a Clioperla clio Perlodid.  Only one, I expected to see a lot more.

Stonefly nymphs like to crawl on the sides of the petri dishes.

Tuesday, November 26, 2013

Case-makers we commonly see in the Winter: Apataniidae, Goeridae, Uenoidae

There are three caddisfly case-makers that we commonly see in the winter that make their cases of pebbles and sand and can be confused: Apataniidae (little mountain case-makers), Goeridae (weighted case-makers), and Uenoidae (little northern case-makers).  Case size is similar with the Goerids and the Uenoids; Apataniids tend to be a little bit smaller.  (That's a little Apataniid in the photo at the top of the page side-by-side with the much larger "humpless case-maker" -- Brachycentrus appalachia.)  But we can normally tell them apart by 1) looking at the cases as the larvae crawl around in our trays, and 2) anatomical analysis -- i.e. microscope work in the lab.

A. The external view (i.e. what we see when we look down at the case)

1. Apataniidae (Apatania incerta is the most common species we see in our streams).   The Apataniid case is composed of very small pebbles/grains of sand and is commonly cornucopia shaped.

It has a "hood" at the top of the case that covers the head of the larva.

That means when you look down on the top of the case, you might see some legs sticking out the sides of the case, but you won't see the head of the larva.  It's very odd to see that case crawling around on its own!

One other thing, if you flip the case over, the larva might peek out, in which case you'll note that the body is yellow.


2. Goeridae (Goera fuscula, Goera calcarata).  The Goerid case is easily recognized by the fact that there are 2 large, ballast stones on each of its sides.  In the center of the case you'll see smaller pebbles.

If the case is inhabited, you will see the head of the larva as it crawls around in your tray.  But you may have to give it some time: Goerids seem to be hesitant to stick out those heads.  One other thing you can see that's important: there are long projections on the sides of the head.  More on those in a minute.

3. Uenoidae (to date, we've seen 5 or 6 species: Neophylax oligius, Neophylax consimilis, Neophylax mitchelli, Neophylax aniqua, Neophylax concinnus, and possibly Neophylax toshioi.  Like the Goerids, Uenoids place larger stones on both sides of their cases for weight -- but they normally have 3-4.

and one of my all time favorites

The largest stones are often placed at the front of the case -- as we can see in all of these photos, and dramatically in the photo below.

Uenoids, like the Goerids, stick out their heads as they move in your tray, but you will not see projections by the side of the head.

B. The internal view (i.e. key larval anatomical features.)  (Things you'll want to know if you work at ID in a lab.)

1. Apataniidae.  The leading edge of the sclerites on the mesonotum is straight -- no indentations and there are no sclerites at the front of the metanotum (sa1).  Rather, in that position, there is a transverse row of setae.

2. Goeridae.  The mesonotum on the Goerid has two pairs of sclerites -- not just one -- and to the side of the mesonotum are those long projections we can see when we look down at the live insect -- the mesepisterna.  Moreover, there are sclerites on the metanotum -- 3-4 pairs depending on the species.   The pronotum is very broad with sharply pointed anterolateral projections.   (The first photo below was taken by a friend and used with her permission.)

3. Uenoidae.  One pair of mesonotal sclerites, like the Apataniids.  But, the leading edge of the mesonotum is "emarginated," or notched, not straight across.

In addition, and again in contrast to Apataniids, Uenoids do have sa1 sclerites on the metanontum.

One other feature to look for on the Uenoids.  If you look at the underside of the head you will see that the ventral apotome is "T-shaped."


There is, of course, a "fourth" case-maker that we see in the winter that makes its case out of pebbles -- the Glossosomatidae, "saddle case-maker."  Here the case is shaped like a dome...

You will probably not see the head of the larva as the case moves in your tray.  But if you flip the case on its back, there's a good chance the larva will crawl out of its case -- something I've never seen with Apataniids, Goerids, or Uenoids.  You'll also see that the case has openings at both of its ends with a "saddle" in-between.

And, with the genus Glossosoma -- the only genus I've seen -- the key diagnostic features can be seen without using magnification.

1. The meso and metanota are completely fleshy without any sclerites, and there are no "humps" -- lateral or dorsal -- on abdominal segment 1.

2. There is a dorsal sclerite on abdominal segment 9.

3. And the anal prolegs appear to be short and "stubby" since the bottom half of those legs are fused with segment 9.


Once more on those cases.

1. Apataniidae

2. Goeridae

3. Uenoidae

4. Glossosomatidae


All four are found in the same places: on the tops of rocks or on the sides of rocks.  But the Goerids don't hold on very tightly.

Saturday, November 23, 2013

The Uenoid caddisfly season begins: "Little northern casemakers" at Lickinghole Creek

With the forecast for Sunday through Wednesday not looking real good, I decided to get out today before the nasty weather moves in.  Where to go?  Well, I hadn't been to Lickinghole Creek in Crozet for a very long time, and it's a good stream to look for Uenoids, so I thought I'd give it a try.
And hooray, hooray, I found a Uenoid -- the first of the season!   It was a very small larva -- 5 mm -- but it still made a very colorful case.

I thought it would probably be the common species Neophylax oligius, but when I looked at my photos I was uncertain about that ID.  Take a close look at the head.

According to Beaty -- "The Trichoptera of North Carolina," p. 87 -- N. oligius has a "yellow stripe on [its] head" which "should be greater than 1/2 [the] head length."  I.e. it should look like this.

That's not quite what we have.  So, what about Neophylax consimilis which has a "stripe or pale area which is less than 1/2 [the] head length"?  (Beaty, p. 86)  N. consimilis looks like this.

Here was my quandry -- was the larva I found N. consimilis, or was it a "young" N. oligius on which the stripe on the head was not fully developed?  Toughy, especially since Beaty notes that the head "stripes" on these two species often blend into one another.

In the end, I had to look at the underside of the head.  On N. consimilis the underside of the head is "usually dark" (Beaty, p. 87); on N. oligius it's usually "testaceous" (brownish red or brownish yellow).  Here's how they differ.

N. consimilis:

N. oligius:

Which do we have?  I'd say it's N. oligius with a stripe that's not yet as long as it's going to be.

Here's a microscope view of the underside of the head on which you can also see the "clavate, ventral gills"  (they're found on both of our species.)

Sorry.  That's a long way to go to establish a species ID, but I like to figure them out when I can.

Other photos today...lots of small winter stoneflies.

1. Small winter stonefly, Allocapnia pygmaea.

2. Small winter stonefly, Allocapnia mystica.  (Note the different shape of the pronotum and the "burnt orange" abdomen.)

3. And of course, there was at least one Clioperla clio Perlodid hanging around.


Welcome back to the Uenoids!