Sunday, July 23, 2017

Montana Part II., Mayflies: Two new ones and two we've seen before


The two new mayflies I found were both flatheaded mayflies.  Both were in the lower Clark Fork River at Petty Creek.  This one, genus Epeorus, species longimanus.

The genus ID was easy -- note the two tails -- and it looks just like the Epeorus nymphs we find in our own streams: pleuralis and vitreus.  But what species?  According to the Montana Field Guide (http://fieldguide.mt.gov/displaySpecies.aspx?family=Heptageniidae), there are four species of Epeorus that occur in Montana: albertae, deceptivus, grandis, and longimanus.   As it turns out, longimanus has one very distinctive mark of identification: there are dark dots in the middle of the femora.  (http://www.flyfishingentomology.com/PNW%20Mayflies.htm)


In addition, "the first and last gills meet under [the] body to form suction discs."  Yes -- though one of the last gills is missing on our specimen.


You may recall that I had previously found another Epeorus -- 9/3/12 -- in a much smaller stream, Grant Creek.


At the time, I identified this one as Epeorus deceptivus.   Just to be sure, I once again consulted Rohrbeck's species descriptions, and I'm pretty sure that I identified that one correctly.    In any event, our ID this time was pretty easy to make: Epeorus longimanus.


The other flatheaded mayfly I found that I've not seen before was very small -- 4-5 mm -- and it was also in the Clark Fork.


Looking at the size and the shape, my guess was Leucrocuta for the genus, and I was right.  The key -- no fibrilliform behind the 7th gill.


Species ID?  Can't do it.  Leucrocuta nymphs are very difficult to identify to the level of species.  In the new book on Larvae of the southeastern USA (see the entry of 7/10) the editors key out L. thetis and L. minerva, but leave untouched, the nymphs of aphrodite, hebe, maculipennis, and juno.   The Montana Field Guide (same page as noted above) notes two species of Leucrocuta that occur in Montana: maculipennis and petersi.    That's as far as we can go.

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Found two other nymphs that I've seen previously in my trips out in August: the small minnow mayfly Baetis tricaudatus -- female and male --  and the spiny crawler Drunella coloradensis.




I'm intrigued by D. coloradensis: it seems to come in all sorts of colors.  Here are just a few that I've found in previous trips.




Pretty remarkable nymph.

Friday, July 21, 2017

New caddis casemakers from my trip to Montana


It was a very good trip.  Fishing was great -- so too was the insect collecting.  In this entry, two caddisfly casemakers that I've not seen before: next entry, two new flatheaded mayflies.

Number one, this neat larva with a prominent dorsal hump and long stringy gills.  Found this one in a backwater eddy of the Bitterroot River, kind of like this one.


The water was still, relatively shallow (1-2'), with a sandy bottom.  There were about a dozen of these crawling along on the sand.

This identification has given me fits.  I got it into my mind -- given that prominent hump and the long, single gills -- that it had to be Phryganeidae (Giant Casemaker).  That led me astray for most of yesterday.  That just didn't work, so I keyed it out and came out to Limnephilidae, Northern Casemaker.   One of the things that led me in that direction was the fact that the mesonotum has sclerotized plates while the metanotum is largely membranous with sclerites at sa1, sa2, and sa3.


That led me to Wiggins (Larvae of the North American Caddisfly Genera, 1977), where I worked through the descriptions and illustrations of the various genera of Limnephilidae.  Even then, the genus ID wasn't real clear.  But in the end, I've decided that the probable genus ID is Psychoglypha (Wiggins, p. 280-281).  Here's Wiggins' description:

Larvae of Psychoglypha spp. are sufficiently divergent morphologically that it is difficult to find characters diagnostic for the genus.  The two sclerites lying close to the dorsal edge of the lateral hump of abdominal segment I provide the only consistent character discovered thus far for all the larvae we have collected.

I can see such sclerites on the larva I found, and, they are the same shape and size that we see in Wiggins' illustration (p. 281).


A few other features.

...in a few species stout spines and setae occur along the pronotum and on the sclerite of segment IX and the lateral sclerites of the anal prolegs.

The spines and the setae on the pronotum seem to me to be present on this particular larva, and the stout setae on the sclerites on segment IX and the anal prolegs clearly have "stout spines and setae."





Head markings usually consist of dark brown spots and blotches on a yellowish brown background, except in P. bella where the head and legs are uniform dark brown.  Abdominal gills are single.  Length of larva up to 26 mm.  

The gills are single for sure (not branched).  The head color -- I see a dark brown head and legs, but P. bella is a species that has not yet been found in MT.  (But it is listed in Rohrbeck in his record of Psychoglypha species. ???)  The Psychoglypha species that have been found in Montana are alascensis, prita, and subborealis.  (See Natureserve Explorer, explorer.natureserve.org).  This larva was only 16 mm, and the case was 29mm.   But I think this larva was still immature.   For the habitat, Wiggins says this: "Psychoglypha larvae occur in a wide range of cool-water habitats, ranging from springs runs to larger streams and their marginal pools."  I can live with a "marginal pool" for this one.  In any event, at this point, Psychoglypha is my best guess for the genus ID.   I might know more if I can get Steve Beaty to have a look at this larva.

More photos.




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Number two, a Uenoid.




I found these Uenoids in a small mountain stream that's across the street from the motel we use: Grant Creek.   There were a bunch of them attached to the rocks near the shoreline.

All Uenoids are genus Neophylax, but what about the species ID?  For a number of reasons, I think it's N. splendens.  Let's go over the data.   To begin with, the source I use to work on genus and species ID for the insects I find in Montana is Roger Rohrbeck's Fly Fishing Entomology, here using the descriptions found in the section "Pacific Northwest Caddisflies" (http://www.flyfishingentomology.com/PNW%20Caddisflies.htm).   There are three species of Neophylax described at this site: occidentis, rickeri, and splendens.  I think we can eliminate N. occidentis.  The pronotum of the species is described as "front 1/3 light, rear 2/3 dark," and "evenly spaced spines at front edge with only a few scattered hairs on rest of pronotum."  Don't see that at all on our larva.  There are quite a few, very small, hairs on the surface of the pronotum, and the front 1/3 is actually darker than the rear.


That brings us to rickeri and splendens.  There are a couple of things that lead me to an N. splendens ID.  First of all, on rickeri, there are "short stout black setae scattered evenly across entire surface of [the] pronotum," while on splendens there are "fewer dark thick setae concentrated towards back."  Have a look.



I'd say there are thick dark setae at the back of the pronotum, with smaller setae mainly along the inner edges of the pronotal plates.

Secondly, Rohrbeck notes that "there are prominent gill-like filaments on the underside of ab1."  That means clavate gills on the venter.


And there they are.  But there is more.  The key source to use on Neophylax species ID is the book The Caddisfly Genus Neophylax (Royal Ontario Museum, 2005), edited by R.N. Vineyard, G.B. Wiggins, H.E. Frania, and P.W. Schefter.  There it is clear that rickeri and splendens are similar in many ways (e.g., dark heads and legs).  But on rickeri they note that the spines on the leading edge of the pronotum are "moderate in size" while those on splendens are "small".  I'd go with small.


Also a critical factor, rickeri is said to inhabit "medium to large streams" while splendens "occurs in small first-to third- order streams.  Grant Creek is, without question, one of the latter.  You might recall the photo I posted in April.


So I'd lean towards N. splendens for the ID.  But as always, I could be wrong, and rickeri can't be ruled out without closer inspection than I can do.
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Good fun as always, and going to Montana in July instead of August -- when we normally do -- means finding a new set of insects.  In the next entry, a look at a new Epeorus and a new Leucrocuta.

Monday, July 10, 2017

We may have found a new Northern Case maker: Pycnopsyche luculenta


On Saturday, as I looked through my reference vials, I discovered a pair of Limnephilids (Northern Case makers) that I had found years ago in the Whippoorwill Branch of the Mechums (one was in the case in the photo above).  I had identified them to the level of genus -- Pycnopsyche -- but not to the level of species.  Decided to give it a try.  I concluded that they were P. scabripennis, but I thought I'd check in with Beaty.  Without seeing the larva, he said that the case looked like that of P. luculenta.  Well, back to the drawing board.

I began by looking at Beaty's description of P. luculenta.  ("The Trichoptera of North Carolina," p. 85)

P. luculenta -- larvae 20-22 mm; head yellowish, dark spots mostly distinct, ventral margin of posterior femora with 3-4 major setae; venter of first abdominal segment with more than 15 setae.  Case a distinctive, slightly flattened cylinder of plant materials with long sticks laterally extending posteriorly.  Common.

Kind of a perfect description of the case.  But let's look at the larva.

1. Pycnopsyche -- single abdominal gills.


2. Pycnopsyche -- long sclerite at base of posterior of lateral hump.


3. Pycnopsyche -- metanotal sa1 sclerites not fused.


Good to go on the genus.  On to the species ID.

1. Size of the larva?  Mine was 20 mm so that fits.

2. Head color and pattern look right.

3.Ventral margin of the posterior femora -- are there 3-4 major setae?  I'd say that there are.


4. The case we've already cleared.  But what about the setae on the first abdominal ventral segment?  I see a total of, maybe 10 setae, and most are very small.


Now that looks like a problem.  There clearly are not more than 15 setae on the first ventral abdominal sternum.  However, when Steve wrote to me yesterday, he sent me a new key on Pycnopsyche, part of a new book that has just been released: John C. Morse, W. Patrick McCafferty, Bill P. Stark, and Luke M. Jacobus, Editors, Larvae of the Southeastern USA: Mayfly, Stonefly, and Caddisfly Species (Clemson University Press).  (I immediately put in my order!)  Let's see what we get using that key.

230.  .... case cylindrical, constructed of stones only........231
230'; .... case cylindrical or depressed, constructed of plant materials or of sand, or stones and often with plant materials..........232

We move on to 232.

232.  Ventral margin of each hind femur with 3 or more major setae.... 233
232'.  Ventral margin of each hind femur usually with 2 major setae.... 234

We've already seen that there are 3 or more major setae on the hind femur.  On to 233.

233. Abdominal sternum I with 12-17 anterior (sa1) setae (mostly very small), 6-7 setae on each posteromesal (sa2) sclerite, and 6-8 setae on each lateral (sa3) sclerite....Pycnopsyche divergens

233'  Abdominal sternum I with 3-11 anterior (sa1) setae (mostly very small), 3-6 setae on each posteromesal (sa2) sclerite, and 2-6 setae on each lateral (sa3) sclerite; case depressed in cross section and with 1 or more long sticks along sides...........streams........... WI to QC south to AL, GA, KY, MS, NC, SC, TN, Pycnopsyche luculenta

The case is a match for P. luculenta.  So too is the number of setae on abdominal sternum I.  What about the number of setae at positions sa2 and sa3?  Two microscope photos.


No problem on the sa2 sclerites: I see 4 on each.  How about sa3?


I can see 2, possibly 3, setae on the lower lateral sclerite.  Have to say that if we use the new key, we key out, indeed, to Pycnopsyche luculenta.  I'll send these larvae to Beaty in a couple of weeks -- when I return from Montana (:  to see what he thinks.  But I feel pretty good about that ID.

One more thing, I have pics of another larva I found in another small stream in Sugar Hollow that also looks like P. luculenta to me.  Very cool.

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While I was working on this yesterday, I decided to use the new key to see what I could find out about the many Limnephilids I've found over the years at the Rapidan River.  Here are pics of a few.






I could go on.  I seem to find 1 or 2 every year.   Using Beaty's description ("The Trichoptera of North Carolina," p. 85), I had concluded, with reservations, that these were all Pycnopsyche scabripennis.  I say reservations because he says that there are less than 15 setae on the "venter of [the] first abdominal segment":  I always see more.   (More than 20, by the way, would lead to an ID of P. guttifer, but that's problematic.  P. guttifer is said to be found in "large, warm streams": that doesn't describe the Rapidan River at all.)

Let's use the new key.  As we did before, we can move to 232 from item 230.

232.  Ventral margin of each hind femur with 3 or more major setae.... 233
232'.  Ventral margin of each hind femur usually with 2 major setae.... 234

Let's see what we've got.  (I'm using the larva in the last photo above.)


In this case I'd say there are no more than 2 major setae on the femur.  On to item 234.

234.  Case mostly mineral; in .....lowland streams.. or possibly spring brooks... or lakes and streams  (that's clearly out)
234'  Case of plant material; in 
...... small to moderate streams
.....  or small to medium rivers (that includes P. guttifera)
.....  or larger streams & rivers
.....  or possibly spring brooks
....   or cool, moderate-size streams ..... Pycnopsyche scabripennis
....   or lowland streams

The Rapidan River is, without a doubt, a "cool, moderate-size stream."


Think my previous ID can stand.  Can't wait to get that new book!
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As noted above, I'm off to Montana for a week of fishing and insect collecting.  Next entry will be a report on those findings.

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Should note, by the way, that I'm not sure that all of the Rapidan Limnephilids I've found were P. scabripennis.  I have found some with cases that look a lot like P. luculenta.  Unfortunately, I can't check them since I no longer have the larvae.