Troutnut Forum > Specimen Discussion > A mystery late-season Epeorus
The Specimen
Epeorus (Little Maryatts) Mayfly Dun
View 9 PicturesI collected this male dun together with a female spinner, a female dun, and another male dun.
View 9 PicturesI collected this male dun together with a female spinner, a female dun, and another male dun.Region: Catskills
Collected Sep 6, 2006
Added Oct 4, 2006
The Discussion
| Troutnut | October 4th, 2006, 1:22 am | |
| Fairbanks, AK Posts: 1122 | This Epeorus species was the only significant hatch I encountered in the remote headwaters of a Catskill stream one afternoon (September 6th, 2006). The small stream is incredibly clear and reportedly very acidic. The duns were coming off sporadically all afternoon and evening on this pleasantly warm, mostly cloudy day with a fleeting dash of rain at one point and sunshine at another. The female spinners were around the whole time but were much more common over the riffles toward evening in groups of 2-10. They were diving to the surface to lay eggs by quickly dipping their abdomens into the water and rising up again for a repeated run. I couldn't find any male spinners, which might make identification impossible, but I did photograph the following: Hopefully this will be enough to eventually puzzle out the ID of this pretty little species. | |
| Jason Neuswanger The Troutnut | ||
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| GONZO | October 4th, 2006, 3:30 pm | |
| "Bear Swamp," PA Posts: 951 | You've got a tough one here, Jason. It certainly seems to conform to Epeorus except that the eyes of the male are not truly contiguous. I've had a look at the NY collecting record and it's not much help. The recorded candidate species are E. fragilis, frisoni, suffusus, punctatus. The latter three seem quite rare, with the only US records coming from a few counties in NY. Only fragilis is recorded outside NY in the US records (ME & CT). None of these are previously recorded from the Catskills. Curiously, the new report (published 2001) of frisoni is the first "since its description (Burks 1946) from one locality in Maine," but the original report does not seem to be included in the current ME record. | |
| Troutnut | October 4th, 2006, 3:58 pm | |
| Fairbanks, AK Posts: 1122 | Yeah, the distribution records tend to be very incomplete, especially for the less common species. It's useful to see some places where a species is present, but the lack of a record doesn't necessarily mean a species is not present. I don't worry too much about the slightly non-contiguous eyes. For one thing, it's a dun -- perhaps the eyes are compressed a bit and they'll fully expand in the spinner form. For another, even the Epeorus pleuralis spinner I collected this spring doesn't have eyes that actually touch. They're a bit closer than in this specimen, but there is a gap. I might be wrong here, but I think we can count them as contiguous if they're separated by less than the width of the median ocellus. Other reasons I'm confident it's Epeorus:
I don't have any good papers on Epeorus species identification. Have you seen any cited that looked intriguing? I can find just about any entomology paper at the Cornell library, but for some genera there's not much to go by beyond very old keys and original species descriptions. | |
| Jason Neuswanger The Troutnut | ||
| Troutnut | October 4th, 2006, 9:02 pm | |
| Fairbanks, AK Posts: 1122 | I verified in Merritt & Cummins that the identifying characteristic for Epeorus males is that the eyes are "touching or separated by less than the width of the median ocellus." So these eyes are consistent with that genus too. | |
| Jason Neuswanger The Troutnut | ||
| GONZO | October 5th, 2006, 3:40 pm | |
| "Bear Swamp," PA Posts: 951 | The wings are much darker than any vitreus I have ever seen; so until someone can suggest a good guide to other Epeorus species, I think it will have to remain a "mystery" Epeorus sp. | |
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