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3. Allright guys...what is it?

I found this last week, in PA from the lower Delaware, near Washington Crossing/New Hope area.


Thanks, CJ

Based on my level of expertise, I'd say it's a fly, possibly a mayfly. I'll leave it to others to either correct me or narrow it down from there.

-Shawn

You are a clever one Shawn!
Mayfly, yes... you are probably right lol

I was thinking Grey Fox, anyone? CJ

CJ,

Your mayfly--yes, Shawn guessed right!--is a female Maccaffertium spinner of one of the species known to fly fishers as Light Cahills or Cream Cahills. The females of some of these species are so similar that they defy identification to the species level, but this looks most like either M. modestum or M. mediopunctatum to me. Their emergence on larger, warmer rivers like the lower Delaware can be quite a bit earlier than on trout streams.

PS--I believe that if you change the IMG to lower case, your photo should magically appear. Meanwhile, here is a very similar example from Jason's collection: http://www.troutnut.com/specimen/296
(As a side note, my species suggestion on Jason's specimen was partly based on its association with a male that seemed identifiable.)

I use to think that was a S. fuscum spinner when I saw that on the Namekagon River.

Yeah, CJ's guess was "Grey Fox" as well. But even under the previous concept of fuscum, the stigmal dots along the sides of the abdomen would be obscure (rather than the distinct little black dots seen in the specimens above), the rear half of the dorsal abdominal segments would be shaded brown (rather than have a narrow black line at the rear), and there would probably be a brown longitudinal stripe down the middle of the dorsal abdomen.

If you can tolerate a little unsolicited commentary on some aspects the fuscum/vicarium confusion/synonymy, read on (if not, don't):

The notion that fuscum was necessarily smaller than vicarium contains an element of misconception, though it is supported by some of the older scientific literature. Depending on the source, the size range for fuscum was supposed to be somewhere between 9-14mm. When Lewis (1974) published one of the last assessments of Stenonema done before fuscum and vicarium were synonymized, he listed the size of mature fuscum nymphs as 10-12mm. But even among the limited examples on this site, you can find exceptions to this. Here is a nymph that would have been classified as fuscum under the old scheme, yet it is already 15mm in April and is not yet fully mature (as evidenced by the short wingcases):
http://www.troutnut.com/specimen/479

The identification as fuscum would have been based on the markings at the rear of the ventral abdomen. Under the old scheme, fuscum had a dark patch on either side (as seen in this specimen), while vicarium had a solid dark band across the rear. However, many variations exist between the two: three dark patches (one in the middle), three dark patches that are connected together, and a dark band that contains a light spot near each cercus base. These are a few of the morphological traits that turned out to be variable or unreliable, and probably contributed to the synonymy.

That said, recent preliminary DNA evidence does seem to suggest that there are two "cryptic" species within what we now know as vicarium. Perhaps vicarium is indeed a species complex, but scientists have yet to discover reliable morphological traits to distinguish between the species. Whatever the case, I think it is unlikely that the "size and color" distinctions traditionally used by fly fishers to distinguish between "March Browns" and "Gray Foxes" will be validated. For the most part, those characteristics have already proved to be unreliable.

John,

Concerning vicarium it may be helpful to quote Gonzo to add a bit more information:

Gonzo: Is it vicarium or modestum that you have heard has the cryptics? Or both? I'm aware of research on the latter, but not necessarily the former.

I always went by Hatches (original version)...

S. fuscum 12-14 mm more amber brown than S. vicarium and 2-4 mm smaller.

I guess life just got easier for fly fishers... Just call them all M. vicarium. :)

Thanks!

Yowww! Man you guys are something! Thanks Gonzo. CJ

Glad to have helped, John. Nice ancillary comments, Gonzo.

-Shawn

Hey Shawn,

My dad used to say that everyone likes a little a$$ every now and then, but nobody likes a smarta$$.

All kidding aside, thanks for that brilliant primary identification.

--Loua$$

I try to contribute where I can, Louis. If that amuses some, so be it. But after reading so many I.D. threads in which I was dizzied by Konchu and Gonzo, I finally saw an opportunity to be of some assistance, and I was darned well going to take it.

-Shawn

I know what you mean. Konchu I can understand; he's trained. But where does Gonzo get off knowing all this stuff? Perhaps I should be picking on him. But I do owe you.

Konchu,

The suggestion of possible cryptics within M. vicarium came from the JNABS "barcoding" paper by Ball, Hebert, Burian, and Webb (2005). After discussing the possibility of cryptics within (or around) Maccaffertium modestum, they say this:

Based on the suggestion in this paper, some fly fishers might be tempted to say "See, I told you that March Browns and Gray Foxes were different species!" But the sequence divergence between vicarium groups was small when compared to the divergences that separated 3 distinct groups within Stenacron interpunctatum (the other "case" referred to above). Divergences between groups within that species ranged from 10%-17%.

However, interspecific divergence (between congeners) ranged from 3.3% to 25.8% in the study, and the divergence of the vicarium groups was within the lower part of that range. (The difference between Baetisca laurentina and B. lacustris was 3.8%, and the difference between Caenis lattipennis and C. youngi was 3.3%.) It should also be noted that samples in this study were very small--the purpose of the study was to test the use of DNA "barcoding" for identification purposes, not to discover cryptic species.

Shawn,

See what I mean? It's almost scary.

WOW Gonzo!!! I can’t speak for the rest of us, but your last post left me absolutely “dun shucked”.

Shawn, Louis, and Falsifly,

Some will probably think that you are unduly impressed by my ability to read, a handy little skill that I picked up between recesses in grade school. However, I admit that it wasn't an easy skill to acquire; I was often distracted from that task by observing the intraspecific morphological variations among the girls in my class. I have also developed the ability to walk upright (most of the time) and to use opposable thumbs (for a few rudimentary tasks). :)

Lloyd-

I think you are being far too modest. Louis is on to something here. I notice (at least) one darned sharp entomologist on BugGuide is now deferring to your opinions on mayfly identification. I am hoping your next book will be on entomology. And, if you think I'm kidding, let me assure you, I am not.

Thank you, Roger.