Thursday, June 22, 2017
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.
(See the tail end of yesterday's entry for a correction to my description of P. guttata.)
Wednesday, June 21, 2017
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'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.
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.
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."
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.
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.
Tuesday, June 20, 2017
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.
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.
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.
Back soon on the various Pronggiled mayflies we've found.
Tuesday, June 6, 2017
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)
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 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.
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.
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?!
Saturday, June 3, 2017
Good morning at the Rapidan River, though the water was high, and I had to stick close to shore.
1. Teloganopsis deficiens. This is only the second time that I've seen this little mayfly. The first was back on June 10, 2012, so it's been awhile. It has a tolerance value of 2.6: as Beaty notes -- "This species in intolerant." (Beaty, "The Ephemeroptera of North Carolina," p. 63)
He also notes that "the double pale dorsal stripe" makes field ID fairly easy, but to be sure we have to check the cerci. On this species, there are no intersegmental setae, just "whorls of spines at [the] apex of each segment."
But for that feature, it could be confused with a Serratella nymph, which it clearly resembles. Very cool.
2. Micrasema wataga.
This is the first time I've found this caddisfly larva (Brachycentridae: "humpless casemaker"), and I'm so bummed that my photos didn't turn out all that well.
Alas. When I first saw this case in my bowl, I was sure that I knew what it was: had to be Micrasema bennetti since I had found that before, back in April 2013.
Note that the case is the same: a round cylinder made of strips of vegetative matter. But, the heads are entirely different.
Beaty describes wataga this way: "head rounded; head pattern mottled brown on lighter background, usually with a pale spot encompassing frontoclypeal angle and surrounding area. Case vegetable and mostly straight." ("The Trichoptera of North Carolina," p. 80) That's a match.
Some other comments of interest. "Micrasema is almost always associated with living vascular plants (moss, Podostemum, etc.) in fast water." This one was attached to a piece of grass that I inadvertently put into my bowl. And on the genus he adds, "Very intolerant. Larvae are generally small in summer...and more abundant and diverse in larger streams, often 2-3 species." And we've got M. wataga and M. bennetti both in the Rapidan River.
3. Perlodid stonefly, Remenus sp. (bilobatus?)
Obviously the best photos I got today. While this nymph keys out to Remenus bilobatus, Beaty cautions to leave ID at the level of genus. There are at least two other known species of Remenus: their larvae have not been described.
The key to the ID? Among other things, the lacinia is unidentate -- no submental teeth.
A good day -- though I'd like to have better photos of that Micrasema wataga. Fortunately, we do have some good pics of the species that my friend took of two larvae she found in the Moormans in June 2012. So much better. She was using a more powerful lens.