Sunday, October 28, 2012
I'm amazed that this photo turned out so well. This large winter stonefly nymph was 1.5 mm long, and it was -- still is -- a dark, cloudy morning! I'm really pleased. (I did add some light with a small LED flashlight.)
In addition, I had to wait a long time for this nymph to get into position. For the first 20 minutes, it stayed curled up in a ball -- which is the large winter's favorite pose. This.
But, success. By January, of course, I'll be thoroughly sick of seeing these things, but finding the first one is always a thrill.
The species? Taeniopteryx burksi, one of three large winter species that I've found in our streams (we'll see the other two before very long: Strophopteryx fasciata and Taenionema atlanticum). Like the small winter stoneflies (Capniidae), large winter stoneflies (family name, Taeniopterygidae) grow up in a hurry. Here is a sequence of stages from photos that I took last year.
11/2/11: Still very small but colors and patterns are more developed.
11/25/11: Note that the wing pads have started to curl (back edge).
12/13/11: Fairly mature. Wing pads are fully developed.
1/5/12: Fully mature. Wing pads are black.
2/6/12: Another one that's ready to hatch.
Most of these nymphs -- this species -- mature and hatch in January and February. It would be unusual to see one in March. Groups that don't monitor their streams in the winter never get to see them.
Taeniopteryx burksi, from p. 8 in Steven Beaty's "The Plecoptera of North Carolina," p.8.
Genus Diagnosis: Nymphs have a single telescopic gill (sometimes retracted) on the coxa of each leg; complete dorsal cercal fringe; some species have a median dorsal stripe.
T. burksi -- male nymphs 8.7-9.5 mm, female nymphs 10-12 mm; femora almost entirely light; light dorsal abdominal stripe bordered by dark stripes; light stripe continues onto head to the epicranial suture; terga with slender bristles and posterior margin with short blunt setae and the occasional long hair; cerci half as long as body with proximal third dark and the remainder yellow.
We can't see all of these features on the tiny nymph that I found this morning -- but we can see some.
Two pairs of the coxal gills are actually visible in one of my photos. They're creamy white, finger-like projections, and note that they're fairly long. (Actually, if you look closely at the photo at the top of the page you can see gills sticking out between the second and third pair of legs.)
Also, while we cannot yet see the light stripe on the abdomen of this nymph, the part that extends to the head is clear, as is the epicranial suture.
But for a good look at the critical T. burksi features, let's have a closer look at more mature nymphs from last year.
ventral view: coxal gills
dorsal view: femora, abdominal stripes, epicranial suture, long cerci that are dark at the base and yellow at the tips.
T. burksi is a large winter stonefly that we see in a lot of our streams. With a TV of 6.6, it's fairly tolerant for a stonefly. Still, it's a beautiful insect, and I'm so glad that the large winter season has finally started.
(For stream monitors -- three features to look for to help with ID on these very small nymphs: 1) they tend to be short: head is wider than the abdomen; 2) the antennae are long and very thick at the bases (pedicels); 3) the body is "freckled," "spotted".)
Thursday, October 25, 2012
Did I Mention That They Grow Up in a Hurry? Clioperla Perlodids and Allocapnia Small Winter Stoneflies
I found the first Clioperla clio Perlodid stonefly of the new season just 12 days ago (see the entry posted on 10/13). It was 4 mm in length. The large Clioperla in the photo above was found in Buck Mt. Creek this afternoon: it was 8 mm long. They mature rapidly once they show up. And note that the distinctive head pattern -- the large pale area that covers the head, surrounded on all sides by a dark border -- is already quite clear on the larger of these two nymphs. On November 25th of last year, I was finding C. clio Perlodids in Buck Mt. Creek that were already fairly mature in terms of color and pattern.
I also found tons of small winter stoneflies this afternoon: the leaves in the leaf packs were covered with them. They too have grown quite a bit in two weeks time (see the entry for 10/11). The tiny nymphs that I found on 10/11 were only 3 mm long; this one was already 7 mm.
With the nymphs I was seeing today, their wing pads show up very clearly, something that was not true of those I found just two weeks ago.
Since they might be difficult to see in this photo, I decided to get a microscope view. The microscope view clearly shows that this is a genus Allocapnia Capniid: "Metathoracic [rear] wingpads usually truncate [squared off], unnotched or notched on inner margin near tip." (Peckarsky, et.al., Freshwater Macroinvertebrates, p. 66) The wing pads on this nymph were notched: the notch is very clear on the left wing pad.
Small winters are also quick to mature. The Allocapnia nymph in the photo below was also found in Buck Mt. Creek on 11/25 of last year. So in four weeks time, we may be seeing nymphs with dark wing pads that are ready to hatch.
It was not my intention to go to Buck Mt. creek when I set out this morning. My first stop was Long Island Creek which is east of Palmyra in Fluvanna county. I had high hopes; this is a very good stream. But my trip there was a big disappointment. The water was very low, and the flow has not really compacted the leaves, so I didn't find a whole lot. The only taxon I saw in big numbers was the Eccoptura common stonefly. This is their kind of water: a small, rocky, forested stream. I took a photo of the largest one that I found (well, it was the largest one that I caught!). It was unusually dark in color.
The other thing I was happy to find in this stream was a number of flatheaded mayflies, species Maccaffertium vicarium.
M. vicarium (the "March Brown" to fly fishermen) has a TV of 1.5 so I don't see it in a lot of our streams. It gets to be pretty big -- 10-18 mm -- and it's one we can ID on sight. The abdomen pattern is very distinctive. From Beaty ("The Ephemeroptera of North Carolina, p. 20): "wide dark bands on posterior margins of both dorsum and sternum of abdomen." And here they are. (The short wing pads indicate that this is a young nymph: M. vicarium usually hatches in March.)
Still searching for the first Large Winter stoneflies of the season. I might have to wait for awhile: we're expecting a visit from Hurricane Sandy!
Tuesday, October 23, 2012
I found this common netspinner larva in the Moormans River in Sugar Hollow on August 10th of last year (2011). It keys out perfectly to Ceratopsyche morosa. On C. morosa, Steven Beaty ("The Trichoptera of North Carolina," p. 73) notes the following features: "head with 5-6 large pale spots in checkerboard pattern on frontoclypeus and usually with three small white spots at posterior angle of frontoclypeus...pale muscle scars laterally on dark pronotum." All of those features are clear in the following photo (6 pale spots on this one). The p1, p2, and p3 arrows point to the three spots at the posterior of the frontoclypeus (central part of the head).
Schuster and Etnier ("EPA Manual," p. 41) say much the same: "Frontoclypeus with checkerboard color pattern; posterior corner of frontoclypeus always [note] with a cluster of three smaller yellow spots. Posterior one-fourth of head yellow." They add on p. 42 "S. morosa [= C. morosa] can be consistently distinguished by the presence of the three small spots clustered in the posterior corner of the frontoclypeus. No other checkerboard-patterned Symphitopsyche [= Ceratopsyche] species exhibits these spots. In all of the other species, if any marking is present in the posterior corner of the frontoclypeus, it is a single, large, yellow spot." Oddly, they say this right after noting that "..on rare occasions, there may be only two small spots rather than three." (???)
There is a reason for drawing attention to the one spot, two spots, three spots point, as you will see.
Now, let's look at a netspinner larva I found at the Rapidan River on 9/5 of this year.
Here is a better look at the top of the head since the pattern is not real clear in these photos.
Note that this has the very same six-spotted checkerboard frontoclypeal pattern, but there are only two pale spots at the back of the head (p1, p2). Three of the netspinners that I found this past Sunday (10/21) at the very same spot in the Rapidan River turned out to have a head that looks much the same, but the anterior spot (number 3 in this photo) seems to be missing.
Here's a microscope view of the head.
Again, there are only two pale spots at the back of the head, spots that are each formed by a fusion of two muscle scars.
Given the checkerboard pattern of 5 or 6 spots on the head of our Rapidan larvae, I've assumed that they are a variant form of C. morosa -- but I've been bothered by the two posterior spots, versus the three that are supposed to be there. (True, Schuster and Etnier do note two spots in rare cases.) So, I've decided to look into this further, and here's what I've found.
1. At the end of Steven Beaty's description of C. morosa, he notes that "C. bifida is considered the west-central form of C. morosa with a head pattern similar to C. cheilonis and does not occur in NC."
So, C. morosa and C. bifida are much the same insect, but the former is found in the East; look for C. bifida in the central and western parts of the country.
2. In an article to which I was referred by a friend (Kurt L. Schmude and William L. Hilsenhoff, "Biology, Ecology, Larval Taxonomy, and Distribution of Hydropsychidae (Trichoptera) in Wisconsin," pp. 123-146 [The Great Lakes Entomologist, 19:3, 1986]), on the other hand, a distinction is made between two different forms of C. morosa: the morosa form and the bifida form. Both forms are said to occur in the state of Wisconsin.
3. And finally, Schuster and Etnier describe Symphitopsyche (Ceratopsyche) bifida and Symphitopsyche (Ceratopsyche) morosa as distinct species.
I think that the netspinner larvae I'm finding in the Rapidan River correspond pretty well to Ceratopsyche bifida and/or Ceratopsyche morosa, bifida form -- even though that species -- or that "type" of C. morosa -- does not occur, so we're told, in this part of the country (!) Keep the following photos in mind -- microscope photos of the head of one of the larvae I found on Sunday -- as we proceed.
1) top of the head, showing the pale spots on the frontoclypeus:
2) side view of the head:
3) ventral view of the head:
1) This last photo is important to keep in mind when we read what Schmude and Hilsenhoff have to say about C. morosa, bifida form: "ventral areas of the head are variable. The basic pattern is three dark areas halfway back, one each on the posterior half of the stridulatory surfaces [= 1 and 3 in the photo], and one mesally on the gular suture [pointed out with arrow 2]. These can fuse to form a transverse band or be reduced to three small spots. More often the pigmentation is extensive, forming a wide "W" shape [emphasis added] as in C. alhedra; this is never the case with C. morosa (morosa form) [emphasis added] or C. bronta." (p. 131) I'd say our larva has a "wide "W" shape" which would make it C. morosa, bifida form.
2) Schuster and Etnier describe Symphitopsyche bifida (Ceratopsyche bifida) in the following way: "Seven spots in checkerboard pattern on frontoclypeus [but I think they have in mind a single anterior spot and a single posterior spot, not the seven spots pointed out on my photo]. Dark brown to black pigmentation on margins of genae forming epicranial arms; this pigment expanded behind eye and reaching ventrally to level of eye. Expanded black area behind eye with number of yellow spots. Posterior one-fifth of dorsum of head yellow; large area around eye and posterad of eye, ventrad of black mark, yellow. Venter of head with large, dark, inverted, Y-shaped mark on stridulatory surfaces." (p. 30. All of those traits are visible in the second photo above: the side view of the head.) On p. 31, they note some variation: "A certain degree of variation has been observed in the larvae of S. bifida, and this variation relates to the number of spots on the frontoclypeus. The central five spots on the frontoclypeus are consistently present, but the medial anterior and posterior spots are variable. Some individuals of the same population may possess all seven spots, while others have only six and lack either the anterior or posterior. While still other individuals may possess only the central five and lack both the anterior and posterior spot." The larva I found on 9/5 does have an anterior spot; those found on Sunday do not. In neither case, however, is there a single posterior spot -- both have two light spots at the rear.
Well, that's where things stand at the moment on the C. morosa issue. I'd be really inclined to say -- as Schmude and Hilsenhoff say about the state of Wisconsin -- that here in Virginia we have both types of C. morosa -- the "morosa form" and the "bifida form". But "officially speaking," C. morosa: bifida -- I take it -- doesn't occur in this part of the country.
Anatomical note: The "frontoclypeus" is that part of the top of the head that is enclosed by the epicranial suture. The "genae" run from the outside of the epicranial suture on top of the head to the gular suture on the bottom of the head.
Sunday, October 21, 2012
It's been a long day. I went up to the Rapidan River this morning, collected some very nice insects, got set up to begin taking photos -- then discovered that I had left my "macro" lens back home! So I had to transport some insects to C'ville before I could get any pictures. The lens I had with me was the "standard issue" Canon lens -- 18-55 mm Zoom. From now on, I'll be taking all of my lenses when I go to a stream.
I did have a couple of insects for which I did not need the macro magnification. A beautiful Paragnetina immarginata common stonefly, and a fairly large Giant stonefly -- Pteronarcys biloba (with a smallish Peltoperlid on its back).
But the find of the day was the Chloroperlid in the photo at the top of the page, the first of the new season. The genus I'm quite sure is Sweltsa. These are stoneflies that takes a long time to develop: we'll be seeing them all winter long. The one below was fairly mature -- it was collected on April 11!
The one I found today was a mere 4 mm long: it has a long way to go. At the moment, the wing pads don't have much shape.
I found two other taxa that we'll be seeing all winter -- the pronggilled mayfly, Paraleptophlebia, and the Roach-like stonefly -- Peltoperlidae -- genus Tallaperla.
(The netspinner in the picture is a genus Cheumatopsyche.) Oh. One other "new" find of the season -- the flatheaded mayfly, Maccaffertium pudicum. It's one of the biggest flatheads we see, and the biggest flathead I've seen in a very long time.
For the rest -- they were all insects we've been tracking through the summer and fall.
1. Small minnow mayfly, Acentrella nadineae.
2. Small minnow mayfly, Baetis intercalaris. Two males, both mature, but two that looked nothing alike.
3. Common netspinner, Ceratopsyche bronta -- the pattern is unmistakable.
4. Common netspinner, Ceratopsyche slossonae.
5. Common netspinner, Ceratopsyche morosa (bifida form). The "checkerboard" pattern of 5 pale dots on the top of the head is not really clear in these photos.