Friday, October 20, 2017

A "Cheat Sheet" for spiny crawler (Ephemerellidae) genera


Ah yes, the mayflies we love to hate.   Come May, there's simply no way to avoid them.  They're all over the place: they're in the leaf packs, in root balls, on the bottoms of rocks and on the tops of rocks, especially if the rocks are covered with moss.   Most of the spinys we see in our samples in May are genus Ephemerella, specifically E. dorothea: for fly fisherman, PED's (Pale Evening Duns).  There are two other genera that I see in the summer -- Serratella and Teloganopis -- but they are not around in large numbers.  It is not hard to sort out the genus IDs for spiny crawlers, though for some features you might need a loupe.


     A "Cheat Sheet" for spiny crawler (Ephemerellidae) genera


I. gills on abdominal segment 4 LARGE, covering those on segments 5-7: Eurylophella

II. gills on segments 3-7 all the same size

1. intersegmental setae dense on cerci (tails) -- tails look "bushy"; all femora the same size: Ephemerella

2. intersegmental setae dense on cerci (tails) – tails look "bushy"; fore (front) femora very broad with "tubercles" (spiny bumps) on the front edge: Drunella

3. cerci "short and spiky" and lack intersegmental setae; "tubercles" present on rear edge of abdominal terga: Serratella


4. cerci "short and spiky" and lack intersegmental setae; no "tubercles" on rear edge of abdominal terga: Teloganopis
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I. gills on abdominal segment 4 LARGE, covering those on segments 5-7: Eurylophella



I've not seen a lot of these nymphs.  I've found a couple in Buck Mt. Creek and some in the small streams in Sugar Hollow.  A spring taxon.
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II. gills on segments 3-7 all the same size

1. intersegmental setae dense on cerci (tails) -- tails look "bushy"; all femora the same size: Ephemerella



(Also the nymph at the top of the page.)


As you can see, they come in a wide range of colors.   This is the spiny genus we most commonly see.  I know we'd all like to see less of them!
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2. intersegmental setae dense on cerci (tails) – tails look "bushy"; fore (front) femora very broad with "tubercles" (spiny bumps) on the front edge: Drunella



Not terribly common.  I've found three different species.  Two of them we find in the spring, the other -- the one in the photo directly above -- is around in June and July.
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3. cerci "short and spiky" and lack intersegmental setae; "tubercles" present on rear edge of abdominal terga: Serratella





A "summer spiny."  They're small: dark brown or black.  Tolerant of warm water conditions.
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4. cerci "short and spiky" and lack intersegmental setae; no "tubercles" on rear edge of abdominal terga: Teloganopis



I've only seen this one at the Rapdian River, so I don't think it's common.  Like Serratella it's around in the summer and it has those short, spiky tails.  You'll need a loupe to check the abdominal segments
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There are four genera in the Southeast that I haven't seen: Attenella, Dannella, Penelomax, and TsaliaAttenella and Penelomax are uncommon and Tsalia is rare.   Not sure we're going to find them.   We could run into Dannella -- "primarily lotic, typically in areas of slower flow and silt, often collected from woody debris" -- though I'm not sure I normally look in those locations.  (See Beaty, "The Ephemeroptera of North Carolina, pp. 45-65.)

Afraid this is a key that you can't really use until next spring and summer, though "tiny spinys" show up in the winter.

Thursday, October 19, 2017

A "Cheat Sheet" for "Common stonefly" genera (Perlidae)


To my surprise, my "Cheat sheet" for flatheaded mayflies was quite a hit, so let me see if this is of interest as well.  Volunteers come to quickly ID common stoneflies (family Perlidae) by the branched gills that stick out to the sides behind each of the legs.  But I think they could also ID the Perlidae to the level of genus with just a smidgeon of work -- and the use of a loupe.  Again, I hope this adds to your enjoyment of picking bugs off of the nets.   Just repeat this mantra -- "heads and tails" -- that's all you need to look at to determine the genus ID.  Look at the top of the head and the base of the tails, specifically, as we'll see, you have to ask are "anal gills" present or absent?

               A Cheat Sheet for "Common stoneflies" (Perlidae)

 1.  only two ocelli on head: Neoperla

2. closely set row of spinules on the back of the head, regular and complete

a.  anal gills present:  Agnetina
b. anal gills absent: Paragnetina

3. spinule row at back of head irregular, can be sinuate with gaps – Perlesta

4. no row of spinules at the back of the head

a. pale "M" pattern on head, anal gills present or absent: Acroneuria

b. no "M" pattern on head, but large pale area in front of anterior ocellus, anal gills present: Eccoptura
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So here we go.

 1.  only two ocelli on headNeoperla



Ocelli are "simple eyes" -- they look like black dots-- on top of the head, two lateral and one anterior.  Together they form the "ocellar triangle."  On Neoperla nymphs, the anterior ocellus is missing: on all other genera it's present.  As below.


Neoperla is a genus I've only seen in two of our local streams, and it's only around in the summer.
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2. closely set row of spinules on the back of the head, regular and complete
a. anal gills present:  Agnetina
b. anal gills absent: Paragnetina

Here's what they look like.



This Paragnetina (P. fumosa), by the way, was in Buck Mt. Creek for local readers.  The other species I see is P. immarginata -- this one --


which I've only seen at the Rapidan River.
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3. spinule row at back of head irregular, can be sinuate with gaps – Perlesta

Perlesta nymphs have anal gills, but that irregular row of spinules really nails it down.  I've seen two different types: one that's densely "freckled,"



and one that's not.


Look for Perlesta nymphs in our streams in May and June -- some in April -- they're not to be found the rest of the year.
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4. no row of spinules at the back of the head
a. pale "M" pattern on head, anal gills present or absent: Acroneuria

b. no "M" pattern on head, but large pale area in front of anterior ocellus, anal gills present: Eccoptura

Acroneuria -- more than one color



Eccoptura

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Don't rely solely on color: always use morphological features: anal gills present, anal gills absent?  row of spinules present or absent?  If present, what type of row do you see?  If there's no row of spinules, is there an "M" pattern, or a large pale area at the front of the head?

And what are you most likely to see?  No question about it -- the chocolate brown Acroneuria with light bands on the posterior edges of the abdominal terga, which is Acroneuria abnormis.  It's the most common "common stonefly" we see, and it's in our streams -- various sizes -- 12 months of the year.


Give it a try.  Have fun!  Just remember the mantra -- "heads and tails."
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(I have time to play around with this kind of thing because our streams are virtually dry.  We need rain, really, really badly, and lots of it.)