Back from Montana with some beautiful insects

I was fishing in Montana last week -- and looking for insects -- and I found some beautiful nymphs, including two large winter stoneflies (Taeniopterygidae) that I've not seen on previous trips.

Number one is this beautiful nymph that I found last Wednesday on the Bitterroot River.  Personally, I think the colors are stunning, and as you can see by the black tips on the wing pads it was fully mature.

From what I can tell, there are five species of "Willowflies" (Taeniopterygidae) in Montana (http://fieldguide.mt.gov/displaySpecies.aspx?family=Taeniopterygidae): Taenionema pallidum (Common Willowfly), Taenionema pacificum (Pacific Willowfly), Oemopteryx fosketti (Saskatoon Willowfly), Taenionema uinta (Uinta Willowfly), and Doddsia occidentalis (Western Willowfly).

As will become clear in a moment, this is not a Taenionema nymph.  Taenionema nymphs, for one thing, are dark brown in color as we have seen with the species we find in our own streams, Taenionema atlanticum.  This one.

That means our nymph is either Oemopteryx fosketti or Doddsia occidentalis.  Both Doddsia and Oemopteryx are described in detail in Stewart and Stark (Nymphs of North American Stonefly Genera, pp. 227-235).   The nature of the laciniae and the mandibles is important in deciding on identification -- unfortunately, my microscope won't allow me to see them very well.  However, there are two other things to consider.  1) The mesosternums aren't the same.  On Doddsia, the stem of the mesosternal ridge is "about equal in length to each arm"  while on Oemopterx, the stem is considerably shorter.  This looks like a Doddsia nymph.

And 2) the shape of the ventral plate is on Doddsia is "semi-ovate", not so on Oemopteryx (see the illustrations on pp. 231 and 234).  We have an oval plate on this nymph (note how the top edges curl in).

While I can't be sure of my identifcation, if I had to guess, I'd say this is Doddsia occidentalis, the Western Willowfly.

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This is nymph number two.

While I found nymph number one in the big, wide Bitterroot River --

nymph number two -- and I must have picked up 50 of them in a matter of minutes -- was in a small stream by our hotel, Grant Creek.

I'd bet the house that these were Taenionema large winter stoneflies.

The color alone is a pretty good sign.  The "brown body color" -- noted in every key that I've seen -- is noted by Stewart and Stark (p. 241) as one of the key "Diagnostic Characters".    Again, I can't see the laciniae and mandibles as I would like, but I can note three other things that help with this genus ID.  1) Beaty notes ("The Plecoptera of North Carolina," p. 23) that the "posterior margin of [the] pronotum [is] wider than [the] anterior margin."  Pretty clear that it is.

2) the sternal plate of the male is "broadly triangular in posterior half and bearing short erect hairs in posterior two-thirds." (Stewart and Stark, p. 241) That's a match.

And 3) there's the legs.  "Legs with continuous, silky dorsal fringe, sometimes sparse on tarsus." (Stewart and Stark, p. 241).  That's also a match.

Taenionema for sure.  Which one -- pacificum, uinta, pallidum? -- I haven't a clue.  I can't find any keys that take this to the level of species.  We need Steven Beaty to move to the West.  (:

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The fishing was great.

The Skwala stoneflies were hatching.  Photos of Skwala nymphs and an adult in my next entry.

Nemourid stonefly, genus Soyedina: here's where things stand

This is the stonefly nymph that I found in Sugar Hollow two weeks ago (March 9): family, Nemouridae; genus, Soyedina; species, initially undetermined.  You will recall that I was intrigued by what appeared to me to be paired tubercles on the posterior edges of terga 1-7.  These.

Steven Beaty was also intrigued and asked me to find more nymphs and/or adults if I could.  As luck would have it, I returned to that very small stream on March 12 and found an adult. I failed in my attempts to get a live photo of that adult, but here's what it looked like when it was preserved in a vial.

I wasn't sure that this was Soyedina, but when I checked the wing veination with sources, that ID was confirmed.   I sent both the nymph and the adult to Beaty.  He determined, first of all, that those "tubercles" were in fact tufts of setae that look bigger than they are due to detritus.  And on the adult, he feels that it's most likely S. carolinensis though the match apparently isn't exact.

Before I go any further let me add this.  At the moment, only two species of Soyedina are attested in the state of Virginia -- S. carolinensis and S. vallicularia. (Stewart and Stark, Nymphs of North American Stonefly Genera, p. 217) North Carolina has a total of four: S. carolinensis, S. kondratieffi, S. washingtoni, and a new, unnamed species -- n.sp. (Beaty, "The Plecoptera of North Carolina," p. 17)  The nymphs for the two species that are found in Virginia have both been described: carolinensis by Claasen in 1923 and vallicularia by Harper and Hynes in 1970.

So, is our stonefly S. carolinensis?  Beaty's best guess so far, but this conclusion is not unproblematic.  Why?  Because Claasen's description of carolinensis makes no mention of "tufts of setae" on the tergites, surely a feature he'd note.  I might add that such tufts are also unmentioned in the description of vallicularia.

We have to leave it at that though there are two other items worth noting.  1) On Bugguide.net, Tom Murray has posted a photo of a nymph that he ID's as S. washingtoni (http://bugguide.net/node/view/260938/bgpage), and, it too has those tufts of hair on the terga.  And 2) there is also a photo of S. vallicularia on which those tufts of setae are present as well (http://www.shl.uiowa.edu/env/limnology/plecoptera.xml)

Lots of uncertainty here in the association of nymphs with adults.  A lot more work needs to be done. Ah, but that's what Ph.D. dissertations are for!
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Here's the place where I found both the nymph and the adult.

Maccaffertium meririvulanum and Maccaffertium pudicum: how we tell them apart

We continue to look for Soyedina Nemourids: so far no luck.   The nymph that I found on 3/9 is one that's as yet "undescribed": it's either a new species of Soyedina or, what's more likely, one that has not yet been associated with an adult.  Steve Beaty wants us to send down more specimens -- so the search will go on.

In the meantime, I've been back to Sugar Hollow a number of times where we're finding numerous insects, including this spectacular flatheaded mayfly, Maccaffertium meririvulanum.  As we've noted before, M. meririvulanum and M. pudicum co-occur in pristine, headwater streams.  They're both fairly big nymphs (meririvulanum, 10-16 mm; pudicum, 11-14 mm) and look a lot alike -- but we can tell them apart.

While the ventral pattern is crucial for identifying almost all of the the Macs, the dorsal view suffices with meririvulanum.  The "V's" give it away.  Reading from Beaty ("The Ephemeroptera of North Carolina, p. 34): "...terga 5 and either 7-8, or 7-9 each with distinct V-shaped pale mark."  On our nymph they're easy to see on terga 5, 7, and 8.

In his descripton he adds: "ventrally pale."  True.

M. meririvulanum is one of the least tolerant species in the genus: TV of 0.5.
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To identify M. pudicum, it's best to go right to the venter, though I do find the orange/pale pattern on segment 7 to be a fairly consistent indication of species.

The venter can have 1 of 2 patterns.  On this nymph this is the venter we see.

Here is how Beaty describes this: "ventrally variable with anterior edges of sterna 3, 4, or 5-9 with irregular transverse markings, reduced on anterior segments on some specimens to medial blotches or oblique dashes and with sternum 9 with anteromedial markings extended to form an inverted "U"." ("Ephemeroptera," p. 35)  The "U" on 9 is obvious.  I'd say the oblique dashes and medial blotches are present on 3-6 (2 as well?), while on 7 and 8 these darken into transverse "moustache" like lines.
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Some of the other things we've been seeing.

1) Perlodid stonefly,  Isoperla similis/pseudosimilis Groups (a young one)

2) Leuctridae (Rolled-wing stonefly), genus Leuctra

3) and a very pretty Northern Case-maker, Pycnopsyche gentilis.

Some very nice photos today -- and a little surprise

The search is on for more Soyedina nymphs and some adults (see previous entry), something I'll explain in subsequent entries.  Suffice it to say that the nymph I noted last time is possibly one that's important, but we need more information.  Anyway, I didn't find any today, but I fared well nonetheless.

1. Above -- one of the better photos I've taken of the small minnow mayfly, Baetis tricaudatus.  I saw some small ones today but as you can see, this one was fully mature.  It remains the only small minnow mayfly I've seen in these tiny streams in Sugar Hollow, and with a TV of 1.5, it's where it belongs.  Some more photos.

2. And I found a couple of flatheaded mayflies, Maccaffertium pudicum, which also like these very small streams.

3. No surprises so far -- but this one was.

A pair of Isoperla, Perlodid stoneflies, and when I was taking my photos I was sure they were the very same species: Isoperla kirchneri group, possibly Isoperla kirchneri.   When I uploaded the photos, I saw that I was wrong.  Here they are again.

The first nymph in both sets is indeed I. kirchneri group, but the second is I. holochlora.  Can you see how they differ? Two things: 1) note the different abdominal patterns, and 2) look at the heads.  On I. kirchneri, the lateral stripes on the abdomen are straight, and the pale spot in the ocellar triangle is open to the rear.

But on I. holochlora, the inside edges of the lateral stripes are curved/scalloped and the pale spot on the head is completely enclosed.

I. kirchneri group nymphs are fairly common in these small mountain streams: not so with I. holochlora.  While I often find these nymphs at the Rapidan River, this is only the second time I've found them in Sugar Hollow.
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Back to Sugar Hollow tomorrow to explore something new -- need to find more Soyedina.

Oh.   And a fairly mature Chloroperlid (Green Stonefly), genus Sweltsa.

The Nemourid we find in our small mountain streams: genus Soyedina

As you can see this nymph was fully mature -- black wing pads -- and I guess I should have brought it home and tried my hand at rearing it.  That's the only way to determine the species.

Nemourid stonefly, genus Soyedina.  Let me read you Beaty's description.  "Nymphs 6.5-8.5 mm.  Pronotum with angulate corners and a distinct sublateral notch; pronotum with well-developed lateral fringe of short, closely set, thick setae; wing pads divergent; legs short, stout."  ("The Plecoptera of North Carolina," p. 17)

This nymph was 8 mm long.  You can see from our photo that the legs are short and stout.  For the pronotum features -- all clear in this microscope photo.

The species is undetermined, but I guess that's true for almost all of the Soyedina that we're liable to find in our streams.   There appear to be five different options: vallicularia, carolinensis, kondratieffi, washingtoni, and n. sp.  (a new species, unnamed).  That's why I should have given rearing a try.  Have to see if I can find another next week.  Location?  One of our small headwater streams in Sugar Hollow.  We've found them there before.  I collected this one in December, 2013.

There is something quite distinctive about this nymph that may help with nymph descriptions: there are evenly spaced postero-lateral tubercles on terga 1-7.

I'm sending this one down to Beaty for further review.  I'll let you know if he has any insights.  Soyedina nymphs are "relatively rare."

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The other insect I collected this morning was a tiny Uenoid -- Neophylax aniqua.

This is the Uenoid we find at high elevations.  The distinguishing features are: 1) a semi-blunt tubercle on the head; 2) 1-3 setae at the ventral sa3 position; and 3) absence of clavate gills.

You can actually see the tubercle in one of my live shots.

But it's much clearer in this microscope view, a view that also reveals 2 setae at sa3.

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Pretty good morning.  Lots of insects in our streams at the moment.