It may have been a VERY odd Lepidostomatid: genus Theliopsyche

Interesting.  Almost every -- well, "every" as far as I know -- Lepidostomatid (common name: Bizarre caddisfly) I see is genus Lepidostoma.  The genus is defined by the case that it makes: "four-sided and usually constructed of quadrate pieces of plant material.  Early instars may have sand case."  (Beaty, "The Trichoptera of North Carolina," p. 81)  However, there is a critical anatomical feature as well: "Head with ventral apotome as long as, or longer than, median ventral ecdysial line."  (Wiggins, Larvae of the North American Caddisfly Genera, p. 155)  That feature is easy to see on the head of this larva preserved in my collection.

Yesterday, I decided I had best check the head on that odd larva from Friday, and here's what I saw.

another view

That ventral apotome is quite clearly shorter than the median ventral ecdysial line!  That suggests that this little larva (~ 6 mm) was genus Theliopsyche, not genus Lepidostoma.

Beaty on Theliopsyche: "ventral apotome of head shorter than median ventral ecdysial line." (p. 81)

Wiggins: "Study of our larval material leads to the prediction that Theliopsyche can best be distinguished by the length of the ventral apotome of the head which is shorter than the median ventral ecdysial line.  Length of larva up to 6.5 mm." (p. 158)

Beaty notes that four species of Theliopsyche are attested in North Carolina -- corona, epilomis, grisea, and melas.  But only one larva has been described to date -- T. melas -- and melas has a "head [that is] flattened with [a] carinate ridge." (p. 81)  Do we see a carinate ridge on our larva?

Possibly, but it's questionable, and that head doesn't look very flat.  So T. melas appears to be out, but we can't rule out some other species.  (According to natureserve.org, T. grisea has been found in Virginia as well as T. melas.)

We can't say for sure that our larva was a Theliopsyche.  But the ventral apotome/ecdysial line ratio certainly corresponds to Wiggins' key to the genus ID.  And, this larva was certainly different than the Lepidostomatids we typically see in this stream: their heads are always burnt orange,

The head on this larva was clearly dark brown.

________________

Stay tuned.  Oh, two other things.  1) Theliopsyche larvae make cases "composed of sand grains, curved and slightly tapered" (Beaty, p. 81), but as I noted at the end of the previous entry, this larva had temporarily moved into a 3-sided leaf case vacated by P. gentilis.  And 2), on habitat -- "Larvae and pupae of T. melas were collected in the clean gravel bed of a small spring run.  Localities for other species of Theliopsyche indicate that they probably live in similar habitats." (Wiggins, p. 158)  We were clearly in the right place to find them.

The "odd" Lepidostomatid: back to Sugar Hollow's small streams

What's wrong with this picture?  Well, that appears to be a Lepidostomatid (genus Lepidostoma) larva in a 3-sided case made of pieces of leaves, and as Wiggins has told us, Lepidostomatid cases "are usually four-sided and constructed of quadrate pieces of bark or leaf." (Glenn B. Wiggins, Larvae of the North American Caddisfly Genera, 1977 [1st edition], p. 156)  They can also, when very young, make cases out of sand grains, and we also find cases that combine the two construction techniques.  So,  we find these

and these

and these

What does make a 3-sided case out of pieces of leaves or bark?  The Northern case-maker, Pycnopsyche gentilis.  This one

Our Lepidostomatid is in the wrong kind of case.  I'm not sure what to make of this find: it could be a matter of species.  Wiggins adds "Final instars in some...species assigned to Lepidostoma have cases of plant materials placed spirally or transversely" (p. 156) so there may be some odd cases around.  In any event, This larva cooperated for some very nice photos, despite it's very small size (about 5 mm).

By the way, I did find other 3-sided cases this morning that did contain P. gentilis larva.  This case for example.

I kept both of the cases you see in these photos, and here's what I found when I looked into my microscope tray.

Very curious!
_________________

I spent the morning at the small stream in Sugar Hollow that runs through a friend's land high above the Moormans.

 The water was low, but we had no trouble finding interesting insects.  Some other photos to look at.

1. Perlodid stonefly, Malirekus hastatus.  This is a "killer," and this one ate one of my Roach-like stoneflies the moment I glanced away?

2. Roach-like stonefly, genus Peltoperla.  Only saw three or four.

3. A "Weighted-case maker": Goera calcarata.  Beautiful case.

4. And last but not least, a "normal" Lepidostomatid in a case made of sand: one of the smallest I've ever seen.

________________

Back up here in the winter -- but we'll be needing some rain.

_______________________

Postscript:  On reflection-- I suspect that our "odd" Lepidostomatid had simply moved into a P. gentilis case that had been abandoned.  It happens.  Seems the most likely explanation.

All the evidence we're going to need: That's Acroneuria lycorias in Buck Mt. Creek

I expected to see winter insects today at Buck Mt. Creek -- and I did: small winter stoneflies, large winter stoneflies (still very tiny), Clioperla clio (only one), Uenoids, and Glossosomatids (Saddle-case makers).  But everything that I saw was covered in silt after heavy rains yesterday.  So, I didn't take a whole lot of pictures.

However, I did find three more Acroneuria lycorias/carolinensis nymphs (look back to the previous entry), so I had a chance to test out my theory.  I argued last time that the A. lycorias differed from A. carolinensis in two different ways: 1) yes, they have anal gills while carolinensis do not, and 2) vs. carolinensis, they lack medial markings on the terga (dashes, a stripe).  All three of the nymphs from today can be used for support of that thesis.

The biggest of the three: 16 mm.

Take a close look at that photo.   No need for a microscope to see the anal gills on this baby, and there are no medial markings.

Here's one that was smaller.  But you can still make out the gills, and note that the tergal bands are fairly regular, something we noted last time.

Beaty does not use the lack of medial marks/stripes to distinguish lycorias from carolinensis.  Have to pass this data along and see what he thinks.
__________________

One other insect of interest this morning: the small case-maker Apatania incerta, one that I don't find very often.

Terrible photos -- best I could do.  Still, we can see the features that are characteristic.  1) the case is "cornucopia" shaped with a hood at the top that covers the head of the larva as it's crawling along; and 2) the larva is yellow in color.  But "proof" requires a microscope view.

The front edge of the mesonotal sclerites are straight across -- vs. those of the Uenoids which are "emarginated."  And there are no sa1 sclerites on the metanotum: in their place we find a setal row:   ("anterior metanotal plates replaced by row of about 20 setae" (Beaty, "The Trichoptera of North Carolina," p. 85.)

I'll be seeing totally different insects on Friday: off to one of my favorite small streams in Sugar Hollow.
__________________

(P.S.  Steven Beaty confirms that there seems to be something to the correlation we've noted: presence or absence of anal gills, presence or absence of medial, abdominal markings.  How about that?  We may be on to something.)

Acroneuria carolinensis, Acroneuria lycorias: How to tell them apart

At the risk of trying your patience, I want to assert in this entry that it is possible to distinguish the nymphs of Acroneuria lycorias and Acroneuria carolinensis, even if the experts these days are hesitant to take a firm stand on the issue.   The nymph in the photo at the top of the page is Acroneuria lycorias: I found it at Buck Mt. Creek on 10/28.  This nymph,

I'd argue, is Acroneuria carolinensis.  It was found at Entry Run on 11/30.
_________________

You'll recall from previous entries (10/23, 10/28, and 11/30) that at issue in telling the two species apart is the presence or absence of anal gills.  T.H. Frison (Studies of North American Plecoptera, 1942, pp. 282-284) had argued that A. lycorias has them, A. carolinensis does not.  However, Beaty waffles on this, noting that on A. carolinensis nymphs "anal gills [are] usually present," while on A. lycorias nymphs "anal gills [are] usually absent, sometimes small."  (Beaty, "The Plecoptera of North Carolina," p. 14.)  The word "usually" (italicized by me for emphasis) sort of muddies the waters.

I want to argue that I've found both species -- that I can prove it -- and my arguments on this are three.

1. Every nymph that I've found that I regard as Acroneuria carolinensis has lacked anal gills.  I preserved the nymph from Entry Run.  Have a look for yourself.  ("Paraprocts" are the lobes adjacent to the anus.)

The only nymph that I've found that I regard as Acroneuria lycorias has them.  They are quite clear on the nymph found at Buck Mt. Creek.  (But you can't see them from the front.)

2. A. carolinensis nymphs, with a tolerance value (North Carolina) of 1.2, should only be found in very good streams: A. lycorias has a TV of 2.1; I would not expect to find the two together -- and I haven't.  As I've noted before, I find A. carolinensis in very clean mountain streams: the Upper Doyles River, not far from the SNP, and Entry Run which is in the Blue Ridge.    Buck Mt. Creek, home to my A. lycorias nymph, while still very good water, runs through fields and pastures.

3.  While I've made points 1. and 2. in previous entries, this one is new.  While it is true that the nymphs of both species look almost exactly alike, they differ in one significant way.  Look closely at the abdomens.

Acroneuria carolinensis

Acroneuria lycorias

Note 1) that the bands on the terga of the carolinensis nymphs are very irregular/wavy; those on the lycorias nymph are not.  They are almost uniform in thickness.  And 2) on carolinensis, there are medial extensions of the dark bands that in some nymphs actually turn into a longitudinal line.  There are no such extensions on the lycorias bands.  (Also of interest, I think, is that odd shaped medial extension on tergite 10 on the lycorias nymph.)

This is why I think that this is important.  Frison includes illustrations of A. carolinesis and A. lycorias nymphs in his study (pp. 282-283), and bingo, we can see the same distinct abdominal patterns on the two nymphs!  His nymphs look exactly like those in the pictures above.
_________________

Acroneuria carolinesis

and Acroneuria lycorias

I think we can tell them apart.

No unusual insects -- but a very special stream

Sugar Hollow: one of the small streams I've explored -- but one that I've been to only two or three times.  It remains the only stream in which I've found the small winter stonefly, Paracapnia angulata.  It cuts a deep defile as it cascades down the side of the mountain, leaving lots of boulders on both sides of the stream.

(That photo almost cost me $600.00: I dropped my iphone into the water right after this shot!  It seems to be okay.  Close call.)

It was no surprise to find lots of Roach-like stoneflies (in the picture at the top of the page) in the leaf packs.  They're common all winter in these small mountain streams.  I don't usually keep them for photos, but I continue to look for a genus I know to be here -- my friend has found it -- one that I still haven't seen: Viehoperla.  It's one that, according to Beaty, "Occurs in undisturbed, small, cold streams..in the Mountains from spring through early fall,"  but it's "rarely collected" ("The Plecoptera of North Carolina," p. 13).  It differs from Tallaperla and Peltoperla (both of them common out here) in that the "thoracic gills [are] single." (Beaty, p. 13)

This one appears to be Tallaperla -- the thoracic gills are double.

_________________

Still common on tops of the rocks in still water pools -- "Weighted-case makers" -- Goera calcarata.  I photographed two that had very nice cases.

A nice view of the sharp point of the anterolateral projections of the pronotum, and a good look at the mesonotal anterolateral projections.

_________________

Lots of common stoneflies around: Acroneuria abnormis and Eccoptura xanthenses and a couple of Leuctrids -- but still too early to find the Paracapnia small winters.  Back in January for that.