Saturday, June 20, 2015

Revised EPT List, and yes, those nymphs were Acroneuria evoluta


Still sweating it out -- literally! -- in central Virginia, and it's supposed to be hotter next week.

Steven Beaty has confirmed that, using current species descriptions, the nymph in the photo at the top of the page appears to be Acroneuria evoluta.  (See the entry of 6/12.)  So, it is a species we find in the Rivanna, usually in the fall, and I've found it at Darden Towe Park in C'ville, and in Fluvanna County at the Crofton bridge.  Apparently, this is the first time this species has been recorded in the state of Virginia.
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On 9/8/12, I posted an EPT List for central Virginia.  While I've tried to update that as things have proceeded, I think it's worthwhile to post a "revised" list based that shows where things stand at the moment.  Here it is.



              EPT Species List for Central Virginia
              (Albemarle, Greene, Madison, Fluvanna)
                 
I. Ephemeroptera (Mayflies)

1. Ameletidae

1. Ameletus lineatus
2. Ameletus cryptostimulus

2. Baetidae (Small minnow mayflies)

1. Acentrella nadineae
2. Acentrella turbida
3. Baetis flavistriga
4. Baetis intercalaris
5. Baetis pluto
6. Baetis tricaudatus
7. Heterocloeon curiosum
8. Heterocloeon amplum
9. Heterocloeon petersi
10. Iswaeon anoka
11. Labiobaetis propinquus
12. Plauditus dubius

3. Isonychiidae (Brushlegged mayflies)

1. Isonychia sp.

4. Heptageniidae (Flatheaded mayflies)

1. Cinygmula subaequalis
2. Epeorus pleuralis
3. Epeorus vitreus
4. Epeorus fragilis
5. Heptagenia marginalis
6. Leucrocuta hebe
7. Leucrocuta juno
8. Leucrocuta aphrodite
9. Leucrocuta thetis
10. Maccaffertium ithaca
11. Maccaffertium meririvulanum
12. Maccaffertium pudicum
13. Maccaffertium vicarium
14. Maccaffertium modestum
15. Rhithrogena sp. (exilis?)
16. Rhithrogena sp.
17. Stenacron carolina
18. Stenacron interpunctatum

5.  Ephemerellidae (Spiny crawler mayflies)

1. Drunella cornutella
2. Drunella tuberculata
3. Drunella walkeri
4. Ephemerella dorothea
5. Ephemerella invaria
6. Ephemerella subvaria
7. Eurylophella verisimilis
8. Eurylophella funeralis
9. Eurylophella sp. (minimella?)
9. Serratella serratoides
10. Serratella serrata
11. Teloganopsis deficiens

6. Leptohyphidae (Little stout crawler mayflies)

1. Tricorythodes

 *7. Caenidae (Small square-gill mayflies)

1. Caenis sp.

*8. Baetiscidae (Armored mayflies)

1. Baetisca sp.

9. Leptophlebiidae (Pronggilled mayflies)

1. Paraleptophlebia mollis
2. Paraleptophlebia guttata
3. Habrophlebia vibrans
4. Leptophlebia

10. Ephemeridae (Common burrower mayflies)

1. Ephemera guttalata


 II. Plecoptera (Stoneflies)

1. Capniidae (Small winter stoneflies)

1. Allocapnia sp.
2. Paracapnia angulata

2. Leuctridae (Needleflies)

1. Leuctra sp.

3. Nemouridae (Forestflies)

1. Amphinemura sp.
2. Ostrocerca truncata
3. Prostoia completa
4. Soyedina sp.

4. Taeniopterygidae (Large winter stoneflies)

1. Strophopteryx fasciata
2. Taenionema atlanticum
3. Taeniopteryx burksi/maura

5.  Chloroperlidae (Green stoneflies)

1. Alloperla sp.
2. Haploperla brevis
3. Sweltsa sp.

6. Peltoperlidae (Roach-like stoneflies)

1. Peltoperla sp.
2. Tallaperla sp.
3. Viehoperla sp.

7. Perlidae (Common stoneflies)

1. Acroneuria abnormis
2. Acroneuria carolinensis
3. Acroneuria sp. (possibly internata, possibly a variety of abnormis)
4. Acroneuria evoluta
5. Acroneuria lycorias
5. Agnetina annulipes
6. Agnetina capitata
7. Agnetina flavescens
8. Eccoptura xanthenses
9. Neoperla sp.
10. Paragnetina immarginata
11. Paragnetina fumosa
12. Perlesta sp.

8. Perlodidae (Springflies and Stripetails)

1. Clioperla clio
2. Diploperla duplicata
3. Helopicus subvarians
4. Isogenoides hansoni
5. Isoperla dicala
6. Isoperla holochlora
7. Isoperla holochlora "A"
8. Isoperla latta
9. Isoperla montana (group)
10. Isoperla similis
11. Isoperla davisi
12. Isoperla orata
13. Isoperla orata (variant form)
14. Isoperla sp.VA
15. Malirekus hastatus
16. Rememus bilobatus

9. Pteronarcys (Giant stoneflies)

1. Pteronarcys biloba
2. Pteronarcys dorsata
3. Pteronarcys proteus


III. Trichoptera (Caddisflies)

1. Rhyacophilidae (Free-living caddisflies)

1. Rhyacophila carolina
2. Rhyacophlia fuscula
3. Rhyacophila nigrita
4. Rhyacophila glaberrima
5. Rhyacophila ledra/fenestra
6. Rhyacophila sp. (banksi?)

*2. Hydroptilidae (Micro caddisflies)

1. Hydroptila sp.

3. Glossosomatidae (Saddle-case makers)

1. Glossosoma nigrior

4. Philopotamidae (Fingernet caddisflies)

1. Chimarra sp.
2. Dolophilodes distincta
3. Wormaldia sp.

5. Polycentropodidae

1. Polycentropus sp.

6. Hydropsychidae (Common Netspinners)

1. Ceratopsyche alhedra
2. Ceratopsyche bronta
3. Ceratopsyche morosa
4. Ceratopsyche slossonae
5. Ceratopsyche sparna
6. Cheumatopsyche sp.
7. Diplectrona modesta
8. Diplectrona metaqui
9. Hydropsyche betteni
10. Hydropsyche rossi
11. Hydropsyche venularis
12. Macrostemum sp.

 *7. Phryganeidae (Giant case-makers)

1. Phryganea sp. (sayi?)

8. Brachycentridae (Humpless case-makers)

1. Adicrophleps hitchcocki
2. Brachycentrus appalachia
3. Micrasema wataga
4. Micrasema charonis
5. Micrasema bennetti
6. Micrasema sp. (scotti?)

9. Lepidostomatidae

1. Lepidostoma sp. (at least 2 different species, possibly more)
2. Theliopsyche sp.

10. Limnephilidae (Northern case-makers)

1. Ironoquia punctatissima
2. Pycnopsyche gentilis
3. Pycnopsyche scabripennis
4. Pseudostenophalyx sparsus

11. Apataniidae

1. Apatania incerta

12. Goeridae

1. Goera calcarata
2. Goera fuscula

 13. Uenoidae

1. Neophylax oligius
2. Neophylax consimillis
3. Neophylax aniqua
4. Neophylax mitchelli
5. Neophylax fuscus
6. Neophylax concinnus

14. Leptoceridae (Long-horned case-makers)

1. Nectopsyche equisita
2. Oecetis sp.
3. Ceraclea maculata

15. Odontoceridae (Strong case-makers)

1. Psilotreta labida
2. Psilotreta frontalis
3. Psilotreta rufa

16. Molannidae (Hooded-case maker)

1. Molanna blenda

As I've done in the past, I will make changes to this as needed.

Thursday, June 18, 2015

New discoveries: the 2014-2015 season


(Perlodid stonefly, genus Kogotus: Clark Fork River in Montana, August 18. 2014.)

I think of the annual "season" as starting each fall and ending the following spring.  So, the 2014-2015 season is pretty much over.  True, I might find a new species or two in the Rivanna River this summer, but in most of the streams that I visit the annual cycle is finished.  So, what did we discover this year in terms of new species (EPT species)?

1. 10/28/14 and 12/27/14.  The common stonefly, Acroneuria lycorias, which we distinguished from Acroneuria carolinensis.

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2. 12/21/14.  A new genus of Lepidostomatid: Theoliopsyche.


This one was not in its own case: that case belongs to a Pycnopsyche gentilis caddisfly larva.  Still, it was a good find since this genus is not all that common.
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3. 12/27/14.  A new genus of crane fly: Dicranota.

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4. 1/2/15.  A humpless case-maker that one of my friends had found twice before, but this was the first time I had seen it: Adicrophleps hitchcocki.


This species is "imperiled" in the state of Virginia.
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5. 1/19/15.  A new Isoperla Perlodid: Isoperla latte.   Found -- where else? -- at the Rapidan River.

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6. 4/12/15.  And a new Nemourid stonefly: Ostrocerca truncata.


7. and 8.  To these we should add two caddisfly species that my friend discovered (for which, see the entries of 11/11/14 and 11/17/14):  Molanna blenda and Psilotreta rufa.
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Summer is here, and it's here in spades!  Day after day our temperatures have been in the 90's with dew points as high as 74ยบ.  Sure hope this abates.   I can't do any stream work until it does.



Friday, June 12, 2015

Was it A. arenosa or A. evoluta? -- a common stonefly (Perlid) that I've only found in the Rivanna


When I found this stonefly on 11/14/13 in the Rivanna at Crofton, I regarded it as a form of Acroneuria abnormis.  When I found it again on 9/1/14,


I did a little more work, concluding, you will recall, that it was actually A. arenosa, or possibly A. evoluta (see the entries of 9/1 and 9/4).   I've worked on it some more, and the evidence points strongly in the direction of A. evoluta.  Let me review what I've recently found.  I'll begin with two points on the "positive"side.

1.  The pattern we see on the head is more in agreement with the description of A. evoluta than with that of A. arenosa.

A. arenosa: "dorsum of head with M-shaped pattern, sometimes faint to absent."  (Beaty, "The Plecoptera of North Carolina," p. 14)

A. evoluta: "dorsum of head with interrupted M-shaped head pattern, appearing as a transverse row of 3 light spots in front of anterior ocellus."  (Beaty, p. 14)

There is indeed "a transverse row of 3 light spots" on the head.


2. Beaty notes that this nymph "keys in Unzicker and McCaskill (1982) to A. mela."  For this information, see Unzicker and McCaskill, "Plecoptera," Chapter 5 in Brigham, Brigham, and Gnilka, ed., Aquatic Insects and Oligochaetes of North and South Carolina, 1982.   The description of A. mela is found on page 5.32.  More important for us -- figure 5.87 on page 5.35 is an illustration of this Acroneuria species, and that illustration is a dead ringer for the nymphs I have found.  (A. mela is now regarded as a synonym of A. evoluta.)
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And now for the evidence on the negative side.  Again there are two arguments that we can make.

1. In his description of A. arenosa, Peter Claassen (Peter W. Claassen, Plecoptera  Nymphs of America (North of Mexico), 1931.  pp. 84-85) says the following about the abdominal segments:  "Abdominal segments brownish, with a row of roundish, yellow spots along the median dorsal line, and with similar spots on the lateral margin of the posterior segments."

2. and in the photo of A. arenosa posted by Chandler (http://www.discoverlife.org/mp/20q?search=Acroneuria+arenosa) those yellow spots are clear.  There are no yellow spots on the median dorsal line of the nymphs I have found.



I'd say we're finding A. evoluta.  There is only one argument against this identification, and it's one I've noted before (9/4/14): A. evoluta is not attested in the state of Virginia according to NatureServe Explorer (http://explorer.natureserve.org/), nor is it verified as a Virginia Acroneuria by Stewart and Stark (Nymphs of North American Stonefly Genera, p. 316).   But since we know it is found in the rivers of Pennsylvania, Tennessee, North Carolina and Georgia (Stewart and Stark), I don't see why it shouldn't be here.
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Additional photos:





Wednesday, June 10, 2015

A review: Common stonefies (Perlidae), genus Acroneuria


I thought I'd make myself useful, while I wait for a crummy summer cold to let go.  This is something I've been wanting to do for myself as well as anyone else who enjoys reading along.

"Common stoneflies" (family Perlidae), genus Acroneuria: what are the species we see?  Two comments before we begin.  1) Genus Acroneuria Perlids are the most common, "common" stoneflies we see in our streams, and 2) keep in mind that this is a genus that Beaty insists is badly in need of additional work and revision.

1. Acroneuria abnormis



(That's also abnormis in the photo at the top of the page.)  This is the most common Acroneuria species I've seen, and I think I've seen it in every stream that I've explored, from the very smallest headwater streams to sizeable rivers like the Rivanna.  Distinguishing features: distinct M-shaped pattern on head, no anal gills, and banded tergites -- anterior dark, posterior light.  Tolerance value: 2.1.
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2. Acroneuria arenosa (could also be Acroneuria evoluta)



To date, this is a species I've only found in the Rivanna.  So, a "river" insect.  Distinguishing features: M-shaped pattern on head pale to absent (arenosa) or reduced to three dots (evoluta), terga uniformly brown, anal gills present.  Tolerance value: 2.4 (arenosa) or 1.7 (evoluta).
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3. Acroneuria carolinensis





Thrives in clean, cold streams of "medium" size -- in my experience at least (upper Doyles, Rapidan, North Fork of the Moormans).  Distinguishing features: head with light M-shaped pattern, banded terga: anterior light, posterior dark, no anal gills present.  Tolerance value: 1.2.
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4. Acroneuria internata (but nymph in photo might be a form of A. abnormis)



This is a species that I've only seen once: small mountain stream, Entry Run in Greene County.   The distinguishing feature is the banding of the abdominal terga: the light posterior bands are of uniform thickness.  (In this case, the light bands are nearly uniform.)  No tolerance value is listed for this species in the documents provided by North Carolina.
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5. Acroneuria lycorias



Similar to A. carolinensis in appearance.  But, A. lycorias has anal gills, and the banding is fairly uniform with no medial markings.  Fairly common in Buck Mt. Creek.  Tolerance value: 2.1.

Beaty provides descriptions for three other species: filicis, frisoni, and perplexa.  These are species that I haven't seen.  All three appear to be relatively uncommon.  (Steven Beaty, "The Plecoptera of North Carolina, p. 14)



Wednesday, May 27, 2015

Leucrocuta flatheaded mayflies: can we ID them to the level of species?


(Note:  This is a follow-up to the entry posted on 5/9/14.)

In 1982, Unzicker and Carlson published a key to Leucrocuta species ID ("Ephemeroptera," pp. 3.72-3.73 in Brigham, Brigham, and Gnilka, Aquatic Insects and Oligochaetes of North and South Carolina).  Yesterday I decided to see what I could make of the nymphs that I've found using that key.   However, before I proceed with my results, let me note at the outset that there's a problem.  According to Beaty, entomologists are now hesitant to rely fully on that 1982 work: some of the characters used to make the ID's overlap from species to species.  A new key is being prepared.  Let's hope that addresses the shortcomings of this earlier key.

That being said, the five species that are ID'd in the 1982 key are the same five listed by Beaty as those that are likely to be found in our streams: aphrodite, hebe, juno, maculipennis, and thetis.  So let's proceed with the key having noted that there might be problems.

Using that 1982 key, I think I can safely ID three of the four nymphs -- or types of nymphs -- that I've found.  They are L. hebe, L. aphrodite, and L. thetis.    The fourth nymph -- the one in the photo at the top of the page -- is likely to be L. juno, but there's not much to go on in the key that we have.

 1. Leucrocuta hebe


Here are some of the key features to see:  "tracheae of gills distinct; pale markings on dorsum of abdominal segments 7 and 8 coalesce to form a large pale blotch; head with 3 pale spots on each side of frontal margin; a row of dark streaks present laterally on each side of venter of abdomen."  Also "V-shaped pale median triangle present on dorsum of abdominal segment 9 and covering most of middle of segment, its apex extending almost to posterior margin."  Let's have a look.


We can see all three of the pale spots at the front of the head, but only on the one side.  Also, note that the large pale spots on segment 7 don't exactly "coalesce,"  but close enough.  I'd say segment 9 matches the description.  Venter?


Yes.  There are dark lateral streaks on all of the segments.  Our key also says: "dark area present at each posterolateral angle of venter of abdominal segment 9, sometimes smaller dark area also present at each anterolateral angle of segment 9, but the dark areas are not connected to form a continuous dark margin." Not exactly what we see with the spots on segment 9, but there clearly are two spots on 9, and they are not connected.

I'd say these nymphs are Leucrocuta hebe.



I should add that Knopp and Cormier would also ID these nymphs as L. hebe (Mayflies, p.152), and our photos agree with the L. hebe photo posted by Donald Chandler (http://www.discoverlife.org/mp/20q?search=Leucrocuta+hebe).
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2. Leucrocuta aphrodite


Segments 7, 8, and 9 on L. aphrodite are the same as we find on L. hebe (pale areas on 7 and 8 coalesced: pale area on 9, V-shaped, with apex close to hind margin).    We can see that in the following photo.  We can also see the 3 pale spots on the edge of the head.


However, the "U-shaped" pale areas on segments 4 and 5 on L. hebe are not found on L. aphrodite, and on L. aphrodite, the "dark areas on [the] femora [are] usually more extensive than [the] dark areas."


The reverse is true on L. hebe.  (Visible in the photos above.)

Beaty notes that "most Leucrocuta in the Piedmont are probably aphrodite" ("The Ephemeroptera of North Carolina," p. 19).  Most Leucrocutas I find are L. aphrodite as well.  (Buck Mt. Creek, Doyles River, etc.)

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3. Leucrocuta thetis


L. thetis is described in the following way: "Tracheae of gills indistinct; pale markings on dorsum of abdominal segments 7 and 8 not coalesced; head without pale spots along frontal margin; lateral dark streaks present only on venter of abdominal segment 9."  For the lack of tracheation in gills --


I would agree.  And here's a good look at the head.



On my nymph, there are two pale dots on segment 8, very little on segment 7.

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4. Leucrocuta juno?




This nymph is very distinctive and differs markedly from the other nymphs we have seen.  Note the appearance of the abdominal segments, and the dark color of the femora with just a few pale spots. However, the description that our key provides is woefully wanting.  1) "Posterior margin of dorsum of abdominal segment 9 brown with anterior part of segment mostly pale; pale V-shaped area absent."  True.


"Gills heavily shaded with purplish-black, with paler areas at extreme tip, on inner median space next to main trachea, and near base of outer margin; dark markings at anterior of sternites 8 and 9, in median area."  The gills are heavily shaded, with pale areas at the tips and in the inner median space.


That's very good.  But, the gills on L. thetis look exactly the same!  (Look at the photo above.)  Unfortunately, I can't see "dark markings at [the] anterior of sternites 8 and 9 on my nymph."


While that might make this nymph L. maculipennis (see p. 3.75), our nymph lacks other critical features of maculipennis (e.g. "pronotum widest at anterior margin").   And, our photo matches the L. juno that Donald Chandler has posted (http://www.discoverlife.org/mp/20q?search=Leucrocuta+juno).  Were it not for that fact, I'm not sure I'd venture the guess that this is Leucrocuta juno.
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That's the best I can do at the moment.  And Beaty is right, the 1982 key is in need of revision.   Still, I think there's a pretty good chance that we can safely ID three of the nymphs that I've found: possibly all four.  Time will tell.

Oh.  One other thing.  I've only seen L. thetis and L. juno -- if I'm right about those ID's -- in small mountain streams in Sugar Hollow.  I suspect they're uncommon.

Saturday, May 23, 2015

A new stream -- Staunton Run -- but nothing in the way of new insects


It was worth a try -- and the scenery was hard to beat.  I parked at the Graves Mill entrance to the Shenandoah National Park, where I look for insects in the Rapidan River.  But today I decided to hike up to Staunton Run just a half mile away.  Just spectacular!  And if I ever wanted my fly rod along, today was the day.  Staunton is a high gradient stream with boulders and riffles and pools, and those pools just had to hold native Brookies (Brook Trout).  But alas...

I was quite sure I'd see different insects today, but I'm afraid it's too late in the season.   The stream was loaded with I. holochloras (Isoperla holochlora A), one of the few Isoperlas we see in late spring/early summer.   There were too many to count.


Some spiny crawlers (E. dorothea) -- most of them fairly mature, and some showing black wing pads.   Two other things.  Clumps of submerged sticks and leaves held a lot of Roach-like stoneflies (Peltoperlidae): most of them were also mature.  Like this one.


I was hopeful that they might be the allusive genus Vieholperla, but they were not.  They were genus Tallaperla.  One of the clues -- the double thoracic gills.


The other thing I saw in large numbers -- the Northern case-makers, Pycnopsyche scabripennis.  I only took photos of one, but the only photos that turned out well were the close-ups.


The old "hot dog" case: long sticks on the sides, bits and pieces of bark in the middle.




As you can see, the sun was a bit of problem (reflection and glare).  Next year I've got to get to this stream early on in the spring.  Have to see if I can find any new Isoperlas.  And I'll probably be packing my fly rod!