Wednesday, December 31, 2014
I had hoped to get into the mountains today, but I didn't have time. So, a quick trip to Buck Mt. Creek -- where the water is still running high. I saw a lot of small winter stoneflies, but they're still not showing color (i.e. maturing) so I'll focus on other things.
Apatania incerta: common name, "little mountain case-makers". I've only seen them in three different streams: Buck Mt. Creek, the Doyles River, and the Rapidan River. Apataniidae, like Uenoidae, used to be considered a genus in the Limnephilidae family (northern case-makers), but is now a family all on its own.
This is the little larva that makes a "cornucopia-shaped" case with a hood at the top that completely covers the larva in the dorsal view,
though on occasion, you can see some or all of the legs.
Worth another look at Beaty's description. ("The Trichoptera of North Carolina," p. 85)
Genus Diagnosis [for Apatania]. Mesonotum with two plates; metanotal sa1 sclerites absent; arrangement of sa1 associated setae in a linear transverse row.
Case: composed of mineral particles and strongly curved, cornucopia-shaped; larger mineral particles laterally.
A. incerta -- larvae 6-9 mm; head dark brown to black; nota brownish-black; anterior metanotal plates replaced by row of about 20 setae.
We can see the shape of the case in the photos at the top of the page. For the "larger mineral particles laterally" -- i.e. a "flange" -- a couple of photos.
The color of the head -- "dark brown to black" -- can also be seen in our photos (also, legs are "yellow brown"). But for the nota, and the row of 20 setae that replaces the sa1 sclerites on the metanotum, best to use a microscope view.
We can actually count 10 setae on the left side of the metanotum. This is, by the way, a fairly intolerant larva. In the tolerance values assigned in North Carolina, the TV is 0.6.
Strophopteryx fasciata: one of our "large winter stoneflies". The largest nymph I found today liked to sit on the A. incerta case!
Strophopteryx nymphs are given a tolerance value of 3.3. I almost always find them in the very same streams in which I find the large winter stonefly, Taeniopteryx burksi/maura. This is the best I could do for a photo,
but it's sure a good match for Beaty's description ("The Plecoptera of North Carolina," p. 7): "abdominal terga yellow with uneven, dark brown transverse bands on anterior half of each tergite; median row of transverse dark dots on each tergite." Here's a close-up of those tergites, and also a look at the ventroapical plate the juts out from tergite 9.
You'll recall from the entry of 12/26, that the large winter stonefly T. atlanticum also has a ventroapical plate that is "broad apically" (Beaty, p. 7). By way of contrast, those on Strophopteryx nymphs are "concave laterally" (Beaty, p. 6). They look like this.
Acroneuria lycorias. And more evidence to support my theory that A. lycorias and A. carolinensis can be distinguished (see the entry posted on 12/17).
Once again, this nymph lacked medial longitudinal markings on the terga, but had anal gills. On this one, the anal gills were gray, sparse, and hard to see.
A closer look at those gills.
A. carolinensis nymphs have medial markings and lack anal gills: A. lycorias nymphs are just the reverse. By the way, I ran this by Steven Beaty, and he thinks this might work out to be true. He finds the same correlation with the nymphs in his collection. Aha!
Hope to celebrate the New Year in the morning by exploring a very small stream in Sugar Hollow.
Saturday, December 27, 2014
I plan to do a lot of exploring this winter: new streams, new waters, and I hope some new insects. That means getting into small streams higher up in the mountains. This morning I tried a small stream that empties into the Doyles even though it wasn't all that remote.
Sort of struck out. Oh, I found plenty of insects: large winter stoneflies (Taeniopteryx), some common stones (A. abnormis), some flatheads, one small minnow mayfly, and lots of Uenoids (all were the "tolerant" N. oligius). The stream was in the woods at the top of a hill. Still, there was a farm up above it, and the rocks -- and the insects as well -- were covered with silt. Ugh!
One thing of interest: this little larva (10 mm), one I've not seen before. From my live photos, it's easy to see the prolegs on the venter, but I needed a microscope photo to see if they were paired, and how many there were.
Five pairs on segments 3-7.
Paired prolegs (pseudopods) with sclerotized apical crochets (curved hooks) on venter of abdominal segments 3-7; larvae in wet to saturated soil along streams..... most Dicranota
As I recall, this one was in a pretty muddied up leaf pack. However, if you look at some of the internet sources, you'll find that it's a fairly intolerant insect. Tom Murray has posted a photo of one that was "netted from a fast flowing rocky mountain stream" (http://bugguide.net/node/view/264471/bgpage), and the North Carolina list of tolerance values gives a TV of 0.0 to Dicranota spp. Maybe I need to see if I can get into this stream upstream from that farm!
Friday, December 26, 2014
I've just returned from one of my small streams in Sugar Hollow where I found that winter is now in full swing. Lots of small winter stoneflies, some Leuctrids (Needleflies), a few small Perlodids, oodles of Epeorus pleuralis flatheaded mayflies on the bottoms of rocks, and Giant stones (Pteronarcys proteus) that are getting fairly mature (they'll hatch in March and April). And I found a large number of the large winter stonefly that we find in these small mountain streams -- Taenionema atlanticum (photo at the top of the page). Beaty says they are "rarely collected" ("The Plecoptera of North Carolina," p. 7) -- a statement I've always found strange. They abound in these small streams, and I find them as well in the Rapidan River.
In the photo at the top of the page, you can make out one of the key features for identification, the "ninth sternal plate [is] broad apically" (Beaty, p. 7).
This can be used to distinguish T. atlanticum from a similar large winter stonefly, Strophopteryx limata. (Beaty, pp. 6 and 7)
And the Uenoids (Little northern case-makers) are starting to show up on the rocks. Picked up two this morning, both were Neophylax consimilis.
(That young Free-living caddisfly larva that shows up in these photos is either R. glaberrima or R. invaria (Banksi complex). Can't be sure which it was since I decided not to preserve it. Both are fairly rare.)
Neophylax consimilis, you may recall is a Uenoid that has "ventral clavate gills" on abdominal segment 1, these...
but it does not have a tubercle on its head. In some cases, the head/face is completely brown -- true of the nymphs that I found this morning -- in others there's an orange/red spot in the center.
That orange/red spot was very clear on this N. consimilis that I found last weekend in a trip to the upper reaches of Buck Mt. Creek. (Click on the photo to enlarge.)
And there was another Uenoid up there, Neophylax oligius.
N. oligius, like N. consimilis, lacks a tubercle on its head, and it has ventral clavate gills. But note the different marks on the face. N. oligius has a long orange stripe on its face that extends from the top to the bottom.
And to end up where we began, Buck Mt. Creek was loaded with a quite different large winter stonefly: the large winter that we see in a lot of our streams, Taeniopteryx burksi/maura.
Pretty easy to recognize this one by the colors and that long, medial yellow stripe that runs the length of the body. But if you want confirmation, flip it over. There are long, telescoping gills at the base of each of the legs (coxal gills).
This is a fairly tolerant nymph with a tolerance value of 6.6. (T. atlanticum has not been assigned a TV: too uncommon.)
Sunday, December 21, 2014
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.
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.
Friday, December 19, 2014
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
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.
I spent the morning at the small stream in Sugar Hollow that runs through a friend's land high above the Moormans.
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.