All the evidence we're going to need: That's Acroneuria lycorias in Buck Mt. Creek

I expected to see winter insects today at Buck Mt. Creek -- and I did: small winter stoneflies, large winter stoneflies (still very tiny), Clioperla clio (only one), Uenoids, and Glossosomatids (Saddle-case makers).  But everything that I saw was covered in silt after heavy rains yesterday.  So, I didn't take a whole lot of pictures.

However, I did find three more Acroneuria lycorias/carolinensis nymphs (look back to the previous entry), so I had a chance to test out my theory.  I argued last time that the A. lycorias differed from A. carolinensis in two different ways: 1) yes, they have anal gills while carolinensis do not, and 2) vs. carolinensis, they lack medial markings on the terga (dashes, a stripe).  All three of the nymphs from today can be used for support of that thesis.

The biggest of the three: 16 mm.

Take a close look at that photo.   No need for a microscope to see the anal gills on this baby, and there are no medial markings.

Here's one that was smaller.  But you can still make out the gills, and note that the tergal bands are fairly regular, something we noted last time.

Beaty does not use the lack of medial marks/stripes to distinguish lycorias from carolinensis.  Have to pass this data along and see what he thinks.
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One other insect of interest this morning: the small case-maker Apatania incerta, one that I don't find very often.

Terrible photos -- best I could do.  Still, we can see the features that are characteristic.  1) the case is "cornucopia" shaped with a hood at the top that covers the head of the larva as it's crawling along; and 2) the larva is yellow in color.  But "proof" requires a microscope view.

The front edge of the mesonotal sclerites are straight across -- vs. those of the Uenoids which are "emarginated."  And there are no sa1 sclerites on the metanotum: in their place we find a setal row:   ("anterior metanotal plates replaced by row of about 20 setae" (Beaty, "The Trichoptera of North Carolina," p. 85.)

I'll be seeing totally different insects on Friday: off to one of my favorite small streams in Sugar Hollow.
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(P.S.  Steven Beaty confirms that there seems to be something to the correlation we've noted: presence or absence of anal gills, presence or absence of medial, abdominal markings.  How about that?  We may be on to something.)

Acroneuria carolinensis, Acroneuria lycorias: How to tell them apart

At the risk of trying your patience, I want to assert in this entry that it is possible to distinguish the nymphs of Acroneuria lycorias and Acroneuria carolinensis, even if the experts these days are hesitant to take a firm stand on the issue.   The nymph in the photo at the top of the page is Acroneuria lycorias: I found it at Buck Mt. Creek on 10/28.  This nymph,

I'd argue, is Acroneuria carolinensis.  It was found at Entry Run on 11/30.
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You'll recall from previous entries (10/23, 10/28, and 11/30) that at issue in telling the two species apart is the presence or absence of anal gills.  T.H. Frison (Studies of North American Plecoptera, 1942, pp. 282-284) had argued that A. lycorias has them, A. carolinensis does not.  However, Beaty waffles on this, noting that on A. carolinensis nymphs "anal gills [are] usually present," while on A. lycorias nymphs "anal gills [are] usually absent, sometimes small."  (Beaty, "The Plecoptera of North Carolina," p. 14.)  The word "usually" (italicized by me for emphasis) sort of muddies the waters.

I want to argue that I've found both species -- that I can prove it -- and my arguments on this are three.

1. Every nymph that I've found that I regard as Acroneuria carolinensis has lacked anal gills.  I preserved the nymph from Entry Run.  Have a look for yourself.  ("Paraprocts" are the lobes adjacent to the anus.)

The only nymph that I've found that I regard as Acroneuria lycorias has them.  They are quite clear on the nymph found at Buck Mt. Creek.  (But you can't see them from the front.)

2. A. carolinensis nymphs, with a tolerance value (North Carolina) of 1.2, should only be found in very good streams: A. lycorias has a TV of 2.1; I would not expect to find the two together -- and I haven't.  As I've noted before, I find A. carolinensis in very clean mountain streams: the Upper Doyles River, not far from the SNP, and Entry Run which is in the Blue Ridge.    Buck Mt. Creek, home to my A. lycorias nymph, while still very good water, runs through fields and pastures.

3.  While I've made points 1. and 2. in previous entries, this one is new.  While it is true that the nymphs of both species look almost exactly alike, they differ in one significant way.  Look closely at the abdomens.

Acroneuria carolinensis

Acroneuria lycorias

Note 1) that the bands on the terga of the carolinensis nymphs are very irregular/wavy; those on the lycorias nymph are not.  They are almost uniform in thickness.  And 2) on carolinensis, there are medial extensions of the dark bands that in some nymphs actually turn into a longitudinal line.  There are no such extensions on the lycorias bands.  (Also of interest, I think, is that odd shaped medial extension on tergite 10 on the lycorias nymph.)

This is why I think that this is important.  Frison includes illustrations of A. carolinesis and A. lycorias nymphs in his study (pp. 282-283), and bingo, we can see the same distinct abdominal patterns on the two nymphs!  His nymphs look exactly like those in the pictures above.
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Acroneuria carolinesis

and Acroneuria lycorias

I think we can tell them apart.

No unusual insects -- but a very special stream

Sugar Hollow: one of the small streams I've explored -- but one that I've been to only two or three times.  It remains the only stream in which I've found the small winter stonefly, Paracapnia angulata.  It cuts a deep defile as it cascades down the side of the mountain, leaving lots of boulders on both sides of the stream.

(That photo almost cost me $600.00: I dropped my iphone into the water right after this shot!  It seems to be okay.  Close call.)

It was no surprise to find lots of Roach-like stoneflies (in the picture at the top of the page) in the leaf packs.  They're common all winter in these small mountain streams.  I don't usually keep them for photos, but I continue to look for a genus I know to be here -- my friend has found it -- one that I still haven't seen: Viehoperla.  It's one that, according to Beaty, "Occurs in undisturbed, small, cold streams..in the Mountains from spring through early fall,"  but it's "rarely collected" ("The Plecoptera of North Carolina," p. 13).  It differs from Tallaperla and Peltoperla (both of them common out here) in that the "thoracic gills [are] single." (Beaty, p. 13)

This one appears to be Tallaperla -- the thoracic gills are double.

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Still common on tops of the rocks in still water pools -- "Weighted-case makers" -- Goera calcarata.  I photographed two that had very nice cases.

A nice view of the sharp point of the anterolateral projections of the pronotum, and a good look at the mesonotal anterolateral projections.

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Lots of common stoneflies around: Acroneuria abnormis and Eccoptura xanthenses and a couple of Leuctrids -- but still too early to find the Paracapnia small winters.  Back in January for that.

Back to Entry Run -- and one more time on the Acroneuria carolinensis/lycorias issue

Safely back from Entry Run: apparently no one thought I looked like a deer (!)

I found a fair number of Perlids -- common stoneflies -- this morning, and most looked like the one in the photo at the top of the page, which I think is Acroneuria carolinensis.  But you'll recall that this ID is an issue (see the entries from 10/23/14 and 10/28/14).  Acroneuria lycorias nymphs look exactly the same.  And while Frison says they can be distinguished by the presence (lycorias) or absence (carolinensis) of anal gills, Beaty argues the distinction isn't that clear.   According to Beaty (in one of the e-mails he sent me), they have found both types of nymph (with and without the gills) in the very same water, so they're not sure that the gills are a real point of distinction.  However, in that same e-mail he told me that if every nymph that I find in the same section of the same stream has them or lacks them (anal gills) then I can probably feel certain about the ID.

The nymphs that I found this morning did not have anal gills.  The nymphs that I found in the upper Doyles River -- similar water to Entry Run -- on 10/23 did not have anal gills.  Every nymph in my reference vial -- and I think they're all from the Doyles -- lacks gills.  I have only found one of these nymphs with the gills -- the one I found on 10/28 at Buck Mt. Creek.  This one.

And these are the gills.

Acroneuria carolinensis has a tolerance value of 1.2; Acroneuria lycorias has a tolerance value of 2.1.  Entry Run and the upper Doyles River are both very clean mountain streams, both of them in or near the Blue Ridge: Buck Mt. Creek, while being a very good stream, runs through farm land away from the mountains.   Pretty clear where I'm going: I think we've got A. lycorias in Buck Mt. Creek but A. carolinensis in Entry Run and the Doyles.   That's my working hypothesis at the moment.
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More photos from Entry Run.

1. More pix of two of the A. carolinensis nymphs that I found this morning.

2. A "weighted-case maker" (Goeridae): Goera fuscula.  They're still around.

Note the sternal plates -- one of the features that helps us with the species ID.

3. A spiny crawler mayfly -- first of the season: Ephemerella invaria (the one with tubercles on the rear edges of the terga).

4. Giant stonefly: Pteronarcys proteus.

5. And another "first of the season," a Uenoid case-maker: Neophylax consimilis.

Dates for the entries in which you can find the evidence for species ID

(Where I plan to be going tomorrow: South River valley on the way to Entry Run.)

Whenever I give the name (Latin) of an insect in a photo I've posted, I worry that recent readers will wonder how I've established that species (or in some cases genus) ID.   So, I've worked back through my previous entries and noted some of the dates where you can find the evidence for specific identifications.  This project is not yet complete: there are still some gaps that I want to fill.  But, this should be a good place to begin and something I hope will be useful.
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                    EPT Species List for Central Virginia

               (Albemarle, Greene, Madison, Fluvanna)

                 

I. Ephemeroptera (Mayflies)

1. Ameletidae

1. Ameletus lineatus 4/11/13

2. Ameletus cryptostimulus 4/11/13

2. Baetidae (Small minnow mayflies)

1. Acentrella nadineae 8/6/11

2. Acentrella turbida 9/30/11

3. Baetis flavistriga 6/6/12

4. Baetis intercalaris 5/28/12

5. Baetis pluto 5/11/12

6. Baetis tricaudatus 2/19/12, 3/5/13

7. Heterocloeon curiosum 7/26/13

8. Heterocloeon amplum 10/11/11, 2/7/12, 1/24/13

9. Heterocloeon petersi 9/18/12

10. Iswaeon anoka 6/25/12

11. Labiobaetis propinquus 8/8/13

12. Plauditus dubius 4/10/12, 5/12/12

3. Isonychiidae (Brushlegged mayflies)

1. Isonychia

4. Heptageniidae (Flatheaded mayflies)

1. Cinygmula subaequalis 3/27/12, 5/4/14

2. Epeorus pleuralis 6/22/11

3. Epeorus vitreus 6/22/11

4. Epeorus fragilis, 5/26/13

5. Heptagenia marginalis 6/14/12

6. Leucrocuta hebe 8/9/12, 5/9/14

7. Leucrocuta sp. (juno?) 5/9/14

8. Leucrocuta sp. (aphrodite?) 5/9/14

9. Leucrocuta sp. (thetis?) 5/9/14

10. Maccaffertium ithaca 6/14/12

11. Maccaffertium meririvulanum 12/13/11, 1/17/12

12. Maccaffertium pudicum

13. Maccaffertium vicarium 10/6/11,  10/10/11

14. Maccaffertium modestum 6/13/14

15. Rhithrogena sp. (exilis?) 5/17/14

16. Rhithrogena sp. 5/17/14

17. Stenacron carolina 6/26/14

18. Stenacron interpunctatum 6/26/14

19. Stenacron pallidum 6/26/14

5.  Ephemerellidae (Spiny crawler mayflies)

1. Drunella cornutella 5/27/12, 5/23/14

2. Drunella tuberculata 4/23/12, 5/17/13

3. Drunella walkeri 4/19/12

4. Ephemerella dorothea 9/16/11, 3/16/13

5. Ephemerella invaria 3/3/12

6. Ephemerella subvaria 9/16/11

7. Eurylophella verisimilis 4/26/12, 5/25/13

8. Eurylophella funeralis

9. Eurylophella sp. (minimella?)

9. Serratella serratoides 6/26/12

10. Serratella serrata 6/26/13, 6/27/13

11. Teloganopsis deficiens 6/13/12

6. Leptohyphidae (Little stout crawler mayflies)

1. Tricorythodes

*7. Caenidae (Small square-gill mayflies)

1. Caenis

*8. Baetiscidae (Armored mayflies)

1. Baetisca

9. Leptophlebiidae (Pronggilled mayflies)

1. Paraleptophlebia mollis 7/25/13

2. Paraleptophlebia guttata 7/25/13

3. Habrophlebia vibrans 6/8/11

4. Leptophlebia 12/23/12

10. Ephemeridae (Common burrower mayflies)

1. Ephemera guttalata 5/2/12, 4/10/14

II. Plecoptera (Stoneflies)

1. Capniidae (Small winter stoneflies)

1. Allocapnia 11/14/12

2. Paracapnia angulata 1/30/12, 12/13/13

2. Leuctridae (Needleflies)

1. Leuctra 2/23/12

3. Nemouridae (Forestflies)

1. Amphinemura sp.

2. Amphinemura sp. (wui?)

3. Prostoia completa 1/17/12

4. Soyedina sp. (washingtoni?) 3/5/13, 12/18/13

4. Taeniopterygidae (Large winter stoneflies)

1. Strophopteryx fasciata 12/15/11, 1/21/14

2. Taenionema atlanticum 12/11/11

3. Taeniopteryx burksi/maura 11/12/12

5.  Chloroperlidae (Green stoneflies)

1. Alloperla 5/26/12

2. Haploperla brevis 4/11/14

3. Sweltsa 12/22/11

6. Peltoperlidae (Roach-like stoneflies)

1. Peltoperla 10/20/11

2. Tallaperla 10/20/11

3. Viehoperla ada

7. Perlidae (Common stoneflies)

1. Acroneuria abnormis 9/13/13

2. Acroneuria carolinensis 10/23/14

3. Acroneuria sp. (possibly internata, possibly a variety of abnormis) 4/20/14, 4/22/14

4. Acroneuria arenosa (possibly A. evoluta) 9/1/14

5. Acroneuria lycorias 10/23/14, 10/28/14

5. Agnetina annulipes 9/13/12, 9/26/14

6. Agnetina capitata 5/26/14, 9/26/14

7. Agnetina flavescens 11/10/13, 9/26/14

8.Eccoptura xanthenses

9. Neoperla 6/21/11

10. Paragnetina immarginata 11/2/14

11. Paragnetina fumosa 4/17/13

12. Perlesta 6/3/12

8. Perlodidae (Springflies and Stripetails)

1. Clioperla clio 10/4/12

2. Diploperla duplicata 11/3/12

3. Helopicus subvarians 4/2/11

4. Isogenoides hansoni 12/6/12, 1/19/14

5. Isoperla dicala 5/11/12, 4/13/13

6. Isoperla holochlora 4/5/14

7. Isoperla nr. holochlora 4/5/14

8. Isoperla montana/kirchneri 4/30/13, 4/7/14

9. Isoperla similis 11/12/11, 2/24/14

10. Isoperla davisi 4/14/13

11. Isoperla orata 6/2/13

12. Isoperla nr. orata 5/8/13, 4/7/14

13. Isoperla sp.1 4/7/14

14. Isoperla sp.2 4/7/14

15. Malirekus hastatus 1/21/12

16. Rememus bilobatus 5/3/12

9. Pteronarcys (Giant stoneflies)

1. Pteronarcys biloba 2/18/12

2. Pteronarcys dorsata 8/16/13

3. Pteronarcys proteus 11/10/12

III. Trichoptera (Caddisflies)

1. Rhyacophilidae (Free-living caddisflies)

1. Rhyacophila carolina 3/7/12, 3/20/13

2. Rhyacophlia fuscula 1/6/12

3. Rhyacophila nigrita 2/10/14

4. Rhyacophila glaberrima 3/11/14

5. Rhyacophila ledra/fenestra 4/19/13

6. Rhyacophila sp. (banksi?) 1/28/14

*2. Hydroptilidae (Micro caddisflies)

1. Hydroptila (?)

3. Glossosomatidae (Saddle-case makers)

1. Glossosoma nigrior

4. Philopotamidae (Fingernet caddisflies)

1. Chimarra 1/12/12

2. Dolophilodes distincta 1/12/12

3. Wormaldia 1/12/12

5. Polycentropodidae

1. Polycentropus 7/19/11

6. Hydropsychidae (Common Netspinners)

1. Ceratopsyche alhedra 10/19/12

2. Ceratopsyche bronta 8/1/12

3. Ceratopsyche morosa 8/1/12

4. Ceratopsyche slossonae 9/6/12

5. Ceratopsyche sparna 7/31/12

6. Cheumatopsyche 12/27/12

7. Diplectrona modesta 3/17/12

8. Diplectrona metaqui

9. Hydropsyche betteni 10/16/12

10. Hydropsyche rossi 10/10/12, 7/7/13

11. Hydropsyche venularis 8/4/12, 10/10/12, 7/26/13

12. Macrostemum sp. 8/2/12

8. Brachycentridae (Humpless case-makers)

1. Adicrophleps hitchcocki 12/2/13

2. Brachycentrus appalachia 7/10/12

3. Micrasema wataga 7/10/12

4. Micrasema charonis 4/25/13

5. Micrasema bennetti

6. Micrasema scotti (?)

9. Lepidostomatidae

1. Lepidostoma 12/13/11

10. Limnephilidae (Northern case-makers)

1. Ironoquia punctatissima

2. Pycnopsyche gentilis 9/14/12

3. Pycnopsyche scabripennis 9/14/12

4. Pseudostenophalyx sparsus 3/12/14

11. Apataniidae

1. Apatania incerta 12/9/12

12. Goeridae

1. Goera calcarata 11/3/13

2. Goera fuscula 10/27/13

 13. Uenoidae (genus, 11/27/12)

1. Neophylax oligius 3/18/13

2. Neophylax consimillis 1/5/13, 3/18/13

3. Neophylax aniqua 1/23/13, 3/1813

4. Neophylax mitchelli 1/21/13, 3/18/13

5. Neophylax fuscus 12/27/13

6. Neophylax concinnus 2/7/13

7. Neophylax sp.

14. Leptoceridae (Long-horned case-makers)

1. Nectopsyche exquisita 9/3/12, 8/9/14

2. Oecetis

3. Ceraclea maculata 5/6/13

15. Odontoceridae (Strong case-makers)

1. Psilotreta labida 11/19/13

2. Psilotreta frontalis 10/29/13

3. Psilotreta rufa 11/17/14

16. Molannidae (Hooded-case maker)

1. Molanna blenda 11/11/14

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I will continue to update this list and fill in the gaps when I can.  Off to the upper reaches of Entry Run in the morning where I hope I won't be shot by someone who thinks I look like a deer!  Dangerous times to work in the mountains.

A third strong-case maker (Odontoceridae) larva: Psilotreta rufa

We appear to have found a third stong-case maker species: Psilotreta rufa.  (Well, there's no "we" involved: the larva was found by my friend in Sugar Hollow, the one who lives next to this superb little stream.)

We've collaborated on the ID, but all of the photos of rufa were taken by her.
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Almost all of the Odontocerids I see are Psilotreta labida, a larva with a broad dark stripe extending from the head through the mesonotum and long, pointed anterolateral pronotal projections.

You'll recall that I found hundreds of them just a few weeks ago in the Rapidan River.  The only other species I've seen -- and I've only found it in one little stream -- is Psilotreta frontalis.

We see that same dark band on P. frontalis -- but the pronotal projections are short.

Clearly, the larva my friend found last week is something entirely different.  There is no dark band on the head and the nota: rather, the head and pronotum are a dark, reddish brown while the mesonotum is almost entirely yellow.

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Our new larva keys out to Psilotreta rufa which Beaty describes in the following way.

(P. rufa) -- larvae up to 11 mm; head and pronotum uniformly reddish brown without stripes but may have darker pigmentation along frontoclypeal and coronal sutures...head longer than wide and relatively flat between carinae; seta 17 about half the length of seta 15; pronotum darker laterally; anterolateral pronotal projections short.  ("The Trichoptera of North Carolina, p. 97)

The color of the head and pronotum, the shape of the head (longer than wide), and the short pronotal projections all show up very well in the following photo.

We might see darker pigmentation along the frontoclypeal suture in the following photo -- but the color distinction is admittedly slight.

But this very nice lateral photo clearly shows that the pronotum is dark laterally, and, I think, that the head between the carinae is "relatively flat."  (The carinae are the raised ridges that run from front to back on either side of the head.)

That leaves us with the question of the relative lengths of seta 17 and 15.  I confess that I had no idea where to look for these setae until we found the following article, one that is referenced by Beaty:  C.R. Parker and G.B. Wiggins, "Revision of the caddisfly Genus Psilotreta (Tichoptera: Odontoceridae)," ROM (Royal Ontario Museum): Life Sciences Contributions, No. 144 (1987).  In that article, on p. 29, the head and nota of P. rufa are illustrated in detail, and setae 17 and 15 are clearly marked: 17 is behind the frontoclypeal suture, and 15 is along the carina, the ridge.  Unfortunaely, despite the very fine photos my friend has provided, I can't be sure I can pick out those hairs!

Nonetheless, Parker and Wiggins describe P. rufa in a way that supports our identification.

p. 10  "head uniformly reddish brown or with pale areas laterally; thoracic nota uniformly reddish brown to pale yellowish."  Yes.

p. 21  "Head longer than wide, and in lateral aspect posterodorsal angle more or less squared; dorsum relatively flat between carinae; seta 17 thinner than, and usually about one-half as long as, seta 15.  Pronotum with projection of anterolateral corner short, about 0.2X middorsal length of pronotumn.  Mesonotum with black marking along posterior ridge extending laterad to posterior inflection."

The point of inflection is where the thin band we can see above the thicker black band rises up at the side.  If you look closely you can see it in the following photo.

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I'm not sure we really need to see the head setae to make this identification given the preponderance of evidence that we have.  Psilotreta rufa.

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Two final points of interest.  1) The habitat for P. rufa (Parker and Wiggins, p. 21) is a perfect match for our stream: "P. rufa larvae occur in small spring seeps and spring-fed streams."   And 2) Parker and Wiggins include the following site among the locations where rufa is found: Albemarle County in Virginia, south fork of the Moormans River above the Charlottesville Reservoir. (p. 22)  Bingo!  Not at all far from the small stream in which this larva is living.