A strong likelihood that this pronggilled is Paraleptophlebia debilis

I've been looking through photos I've taken of mayflies, looking for Pronggilled mayflies, and yesterday I came across this one, a picture I took in May of 2012.  If you look closely at the terga you'll note that this appears to be the same species of one of the nymphs my friend found in Sugar Hollow.

The same crescent shaped marks on the anterior edges of terga 4-6, and the markings on terga 7-10 match up as well.  Also of note, 1) the gills lack lateral branching, and 2) there are posterolateral projections on terga 8 and 9.

Those features alone -- the lack of tracheal branching and the posterolateral projections on 8 and 9 -- would lead to a Paraleptophlebia debilis ID in Mayflies by Knopp and Cormier (p. 269).   But I'd prefer to have additional confirmation.

Let's look at Donald Chandler's Key to Species of Leptophlebiidae.  Now, I no longer have a specimen that I can examine, which means I can't look at the maxillary palps, and that's a problem.  To be certain of our ID, we'd have to see palps on which -- in contrast to those we see on P. strigula and P. guttata (see the entries of 6/23 and 6/25) -- the "Segments of [the[ maxillary palpus [are] comparatively short."  But I think that that's a pretty good bet.  Why?  Because there are three species with "elongate" segments -- P. strigula, P. guttata, and P. ontario -- and we know from our previous entries that this is not strigula or guttata, and ontario has "Abdominal tergites [that] are largely yellowish with irregular brown markings."  No match there.

That takes us to dichotomy 9.

9. Abdominal tergites mottled; legs pale, barred with darker brown........paraleptophlebia debilis.
Legs uniformly brown or nearly so......10 

I'm fine with calling those terga "mottled," and the legs do look "pale [but] barred with darker brown," at least on the nymph that was found by my friend.
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Not a certain ID.  But if my reasoning is solid, I think there's a pretty good chance that we've found a third Pronggilled species that inhabits our small cold-water streams.

Getting to know the Pronggilled mayflies

I went up to the upper stretch of the Doyles River this morning -- just short of where it flows out of the Shenandoah National Park.  I wasn't sure what I was going to find, but this one surprised me.  It's a Pronggilled mayfly that I've found at the Rapidan River and in the small streams in Sugar Hollow.  The upper Doyles -- in terms of size -- is somewhere in-between.  Paraleptophlebia guttata.

And I saw a lot of them.  At 6 mm, this was the largest, that most were smaller indicates they'll be around for awhile.

I decided to work more on the ID using two sources.  First, Unzicker and Carlson's article on "Ephemeroptera" in Aquatic Insects and Oligochaetes of North and South Carolina (pp. 3.59-3.60).  In their key, item 2. is

Tracheae of gills with conspicuous lateral branches.......................3
Tracheae of gills without conspicuous lateral branches..................4

Pretty clear from the first photo above that we move on to 4.  There we find

2nd and 3rd segments of each maxillary palp together 1.3 to 1.5 times the length of the 1st (basal) segment......................Paraleptophlebia guttata (McDunnough)

I measured -- no need to go further.  The segments of the maxillary palps, like those of P. strigula, are all "elongate" (to use Don Chandler's term), and I found that with this nymph, segments 2. and 3. combined were 1.38 times as long as 1.  Done.

But I also looked at Chandler's Key for the "Species of Leptophlebiidae," where after his description of the maxillary palps we find this.

8. Abdominal tergites largely dark, shining brown, with narrow pale submedian streaks at anterior margin; legs pale; length 7 mm; common in NH....................paraleptophlebia guttata

While my nymph only measured 6 mm, everything else is a match.  Here's a good shot of those "narrow pale submedian streaks" on the tergites.

Very pleased with the quality of the photos that I got this morning.

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But I'm learning some things.  For example, 1) on my way out to the Doyles this morning I was pondering the difference between the pronggilled nymphs that have branched gills vs. those devoid of any branching.  Could it be that the "branching" helps with the absorption of dissolved oxygen? That might mean that those with branched gills are slightly more tolerant than those without.  After all, the species we find in the small, very clean streams in Sugar Hollow have gills that lack tracheal branching.  Have to give up on that theory. Previously, the only pronggilled nymphs that I've seen in the Doyles River are those with tracheal branching.  E.g., Paraleptophlebia sp. (mollis?)

and genus Leptophlebia.

But now we've got P. guttata in here as well.

2) Different pronggilled species seem to show up at different times.  The Paraleptophlebia. sp. (mollis?) nymph in the picture above was found in the month of March, the Leptophlebia nymph in the month of December.  No longer see either one.  At the moment P. guttata's the only show in town.  It appears to be a late spring/summer species.

And 3) while I thought P. guttata might be uncommon, I've been disabused of that idea.  It seems to be plentiful in the Doyles -- i.e. "common" -- as it is in NH, at least this time of year.
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So much to learn. so little time.

Yes. It keys out to Paraleptophlebia strigula

Always exciting to find something new, especially when it's something that has not yet been attested in the state of Virginia.

Pronggilled mayfly, Paraleptophlebia strigula.  Donald Chandler of the University of New Hampshire has shared with me his Leptophlebiidae Key for New England and here's how that works.

3. Trachea of gills with lateral branches 4
    Trachea of gills without lateral branches 6

Our nymph lacks tracheal branches

6. Segments of maxillary palpus all elongate, each at least 4X as long as wide, together about twice as long as maxilla  7
    Segments of maxillary palpus comparatively short, less than 3X as wide as long, together only slightly longer than maxilla  9

Using photos I printed out to get an accurate read of the ratios, it is clear that we move on to "7"

7. Posterolateral angles of abdominal segments with gills bearing a black streak along margin; known from CT and ME; length 8 mm  Paraleptophlebia strigula

The black streaks are clear in my photos.  My nymph only measured 6 mm -- but it was still immature.  I'll look for something more mature later on in the summer.

And let's not forget the posterolateral projection on segment 9, absent on 8.

I'd say the identity is confirmed.
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NatureServe Explorer says this species is attested in the following states: CT, IN, KS, MA, ME, MI, OH, and PA.  Seems to me that VA can be added to the list.  Also worth noting, although Beaty does not mention P. strigula as a species that occurs in NC, there is evidence that it very well might.  Don Kirk, in his book Hatches & Fly Patterns of the Great Smoky Mountains (p. 59) lists Paraleptophlebia strigula as one of the Blue Quills that is found in the national park.  That leaves TN, NC, and GA as possible locations as well.
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All of a sudden, pronggilled mayflies become interesting (:  And don't forget that there are two other genera that we can explore.

Habrophlebia (vibrans), and

Leptophlebia

Time to start paying attention.

Paraleptophlebia strigula? An intriguing possibility

A follow-up to my two previous entries.  As I was putting my copy of Knopp and Cormier away this morning, I took another quick look at their descriptions (Mayflies, p. 269) and noticed that they list another species of Paraleptophlebia that is found in the East -- P. strigula.  They describe the nymph as follows:  1) tracheal branching on gills: absent; 2) posterolateral projections or spines: present on abdominal segment 9; and 3) abdominal markings: "dark streaks along body margin".   Those "dark streaks" rang a bell.  Have a look.

Absolutely.  But is there a posterolateral projection on segment 9?

Yes!  And nothing on 8.  Hmm....

One problem.  This is a species that is not attested in the state of Virginia.  Its provenance is from New England down to Ohio and Pennsylvania.  But then, we're awfully close to Pennsylvania, so I'd not be surprised to find it in some of our streams.

I'm trying to learn more from entomologists.  Let you know what I find.

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(See the tail end of yesterday's entry for a correction to my description of P. guttata.)

The "Blue Quills" -- Pronggilled Mayflies: Focus, genus Paraleptophlebia

We seem to be seeing a lot of pronggilled mayfly nymphs this summer, so I thought I might review and comment on the problem of species identification.  Steven Beaty's advice is "LEAVE AT GENUS" for the identification of Paraleptophlebia ("The Ephemeroptera of North Carolina," p. 79), and for very good reason.  The most detailed species descriptions I've seen rely on minute details of the labrum, mandibles, maxillae, and hypopharnyx -- and I can't determine those things with the microscope that I use.  (See R.P Randolph and W.P. McCafferty, "First Larval Descriptions of Two Species of Paraleptophlebia," Entomological News, 107 (4), pp. 225-229, 1996.)  I'll focus on description of observable features -- but even there clear distinctions can be made.

Let me start with a common distinction -- the nymph has "branched" or "unbranched" gills.

I. Branched

I've found two different nymphs that share this feature.  The first, the one at the top of the page.  This one.

I think this nymph is fairly common.  There are a lot of these at the Rapidan River and in South River as well.  This one from the South.

There are three distinguishing features: 1) the gills are branched (Randolph and McCafferty, "middle trachea with dark lateral branches"); 2) there are posterolateral projections/spines on terga 8 and 9: and 3) there are pale medial marks on terga 3-7.  To wit:

This is a nymph I usually see from winter through early spring.

The second nymph with branched gills that I've seen is one that my friend has found in Sugar Hollow.

She found this on on 1/23/15, and note that the wingpads are already long, so it is also around in the winter.  This nymph/species also has branched lateral gills and posterolateral projections, but the abdomen is virtually devoid of a pattern (except for, possibly, a pale lateral stripe?).

Possible species IDs?  Knopp and Cormier (Mayflies, p. 269) list two Eastern species with branched gills -- P. adoptiva and P. mollis -- but neither one has posterolateral projections.  Unzicker and Carlson (Aquatic Insects and Oligochaetes of North and South Carolina, p. 3.60) list these same two species as "branched."  Randolph and McCafferty, on the other hand describe a third species -- P. assimilis -- as having both branched gills and posterolateral projections.  So a possibility there.
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II. Unbranched

Here I have four nymphs/species to describe.  The first, the one I think is P. guttata.

Found this one at the Rapidan River, and this one

just two weeks ago in Sugar Hollow.  (My friend found another last week.)  There's not much to describe, not much of a pattern on the abdomen or the head.  The gills are lack lateral branching, and, importantly, there are no posterolateral projections on terga 8 and/or 9.

This matches the description given by Knopp and Cormier, and my photos match those posted by Donald Chandler on DiscoverLife (http://www.discoverlife.org/mp/20p?see=I_DSC155&res=640).
Detailed microscope work would need to be done to be certain of our ID, but at the moment I'd bet on P. guttata.

Next up, that little nymph I found yesterday.

The gills are clearly unbranched,

and there were no posterolateral projections that I could detect (very small nymph, 5-6 mm).  To me, the abdominal pattern is very unique.

Note how the anteriors of terga 2-7 are pale, and those pale areas extend down to the sides.  This is the first time that I've seen this pattern.

Number 3, a nymph that my friend found earlier this month,

and similar to it, one of the nymphs that I found on June 6.

Unbranched gills, posterolateral projections present, and, we can see those pale parentheses marks
( ) on some of the terga.  Also worth noting, the legs -- on her nymph at least -- seem to be dark in color, possibly banded.

One more, another nymph found by my friend in the very pure stream that flows by her house.

I don't think we know if this one had posterolateral projections, but the abdominal pattern is very distinctive.  We can again see the parentheses marks on the terga, but in addition, the posterior edges of the terga are light and they project anterolaterally.

If we set aside the guttata, can we suggest IDs for the other three nymphs?  There's a possible ID for this one.

It's a pretty good match for P. debilis which has pale legs with dark bands (Unzicker and Carlson, p. 3.60).  Chandler has posted a photo of this one -- http://www.discoverlife.org/mp/20p?see=I_DSC154&res=640 -- and there too, there are distinct pale markings on terga 7-10.  For the rest, more work is needed.  Randolph and McCafferty describe a species with unbranched gills and posterolateral projections -- P. jeanae.  A possibility there.  And Unzicker and Carlson note two other Eastern species with unbranched gills -- P. volitans and P. moerens.  Both are noted as having legs that are "uniformly brown or nearly so."
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That's as far as I can go at the moment.  Intriguing.  I must confess that before we started checking this spring, I assumed we only had a couple of Paraleptophlebia species here in our streams.  No longer the case.  I'll be checking things closely as the summer proceeds.  Beaty lists 11 possible species for us to find.  But, not all of those nymphs have been described, and some are rare, "vulnerable to extirpation."  Between Unzicker and Carlson and Randolph and McCafferty, nine species can be keyed out.  But I'll have to leave certain IDs to the professionals with their professional microscopes.

Paraleptophlebia nymphs are intolerant and are only found in good streams.  Tolerance Value for the genus in general is 1.2.
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CORRECTION (6/22/17):  In my description above of P. guttata, I incorrectly said that there are no posterolateral projections on segments 8 and 9.  There is a projection on 9 but none on 8.  (See Knopp and Cormier, p. 269)  This is easy to see in the photo my friend took of a nymph that she found.

Something old something new in Sugar Hollow this morning

In the last month as we've searched our streams for Isoperla sp. VA (still no luck), we've been finding a fair number of Pronggilled mayflies, genus Paraleptophlebia  -- and, they all appear to be different.  We think we're seeing 4, maybe 5, different species, and while it may be difficult to identify the species, we can make some observations.  I intend to work this up into an entry either tomorrow or Thursday.

This was a "new" one today.  It's long and thin, much like P. guttata, but neither the head pattern nor the abdominal pattern looks the same.  Here's what we're pretty sure is guttata.

More on this in a forthcoming entry.

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The old -- well "old" in more ways than one -- another fully mature Leuctrid (Rolled-winged stonefly), genus Leuctra.

So small -- 7 mm -- but so pretty.

I actually had two in my bowl, intending to take pictures of both.  But when I stopped to set up for my photos, I had one nymph and one shuck!  The little bugger had hatched.  Regret not keeping the shuck for a picture.
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One more "old" nymph, both because we've seen it a lot and because it's almost ready to hatch, the flatheaded mayfly, Maccaffertium merririvulanum.

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Back soon on the various Pronggiled mayflies we've found.

A gorgeous, fully mature Leuctrid (Needlefly, Rolled-winged stonefly)

I think this is the first time that I found a Leuctrid that was fully mature -- wing-pads are totally black.  Gorgeous colors.

Before this, the closest I got was one with "tan" wing-pads -- the stage before they turn black.  (photo from 5/30/12)

At 5.5 mm, it's a very small stonefly.  They're numerous in the small mountain streams in Sugar Hollow, and it seems that we see them all season long.  But we've clearly moved into the time of year when some of them -- there may be a different species that we see throughout the summer -- mature and hatch.  Tolerance value of 1.5.  It's one that we have to leave at the level of genus -- Leuctra.  Beaty notes that there are at least 10 species of Leuctra in North Carolina, many of which remain undescribed.  ("The Plecoptera of North Carolina," p. 11)

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But that Leuctrid is only one of the insects I ran into this morning that was mature and ready to hatch.  Another -- this prong-gilled mayfly, Paraleptophlebia.

And I found a second prong-gilled mayfly that was clearly some other species.  This one.

The differences between these two nymphs is rather pronounced.  They differ in color, length, abdominal shape, and overall pattern.  Compare.

The burnt orange nymph -- the one with the black wing-pads -- measured 4 mm; the dull brown nymph was 5.  I think you can also tell from this photo that the head patterns are very different.

Species ID?  I haven't tried it, but I might give it a go.  According to Beaty, "With species descriptions from Randolph and McCafferty (1996), the Unzicker and Carlson (1982) key can be used to separate out nine potential NC species." ("The Ephemeroptera of North Carolina," p. 79)  Sounds like a project for a rainy day.

Until then, I've noted before that were we to use the photos provided in DiscoverLife (http://www.discoverlife.org/mp/20q?search=Paraleptophlebia), we might conclude that the burnt-orange nymph

was P. mollis, while the dull brown nymph

was P. guttata.  Still, we can't go by pigmentation alone.  Time to get to work with that key.
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One more nymph with darkening wing-pads, though not yet completely mature.

I thought this might be an early Epeorus vitreus nymph, but it turned out to be a late-blooming Epeorus pleuralis.
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Oh.  My good friend who lives in Sugar Hollow has recently sent me some photos of a stonefly adult that she thought might be a Leuctrid.

Sure looks that way to me.  Much prettier as nymphs -- yes?!