Mayfly Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)

The following is from an older post of Gonzo's.

It's been my suspicion for quite some time that a good part of the credit given to dorothea for creating the later, lighter-colored "little sulphur" hatch should probably go to the same species (or species complex) that creates the earlier, larger, darker hatch--E. invaria. Many anglers who fish the small suphurs on valley limestone streams in my home state believe (or have been led to believe) that they are fishing the dorothea hatch. Close inspection of the mayfly that causes the activity usually doesn't bear that out. Most of the true dorothea hatches seem to come from mountainous areas where the streams are faster and have rockier bottoms.

All of the specimens in this section are from PA, and this seems to provide a good case in point. This specimen and the nymph (#766) are good examples of dorothea, and they both came from sections of the Brodheads in the Poconos. The other specimens came from big limestoners and appear to be invaria. Notice that all of the dun and spinner specimens, except for this one, have banded tails (dark markings at the segments). As far as I know, this is not characteristic of the Eastern version of dorothea (E. dorothea dorothea), but it is a trait of invaria.

I've often speculated the same thing as I've seen examples of eastern invaria that look virtually identical to some of infrequens out West. Compare the specimen I posted http://www.troutnut.com/specimen/1013 to this one of Spence's http://www.troutnut.com/im_user_ident/picture_219_large.jpg Any thoughts guys?

Hi all,

Comparing the hind and forewings of various ephemerellids was briefly discussed in a couple of related threads recently. Some of the interesting questions posed were whether comparisons could be used to differentiate species, differentiate between gender, or differentiate between dun and spinner stages. This motivated me to closely study the photos on the hatch pages; especially since scientific papers and angling texts are largely mute on the subject of wing shape when describing the differences among ephemerellids. May it turn out to be important in helping with photo determinations, at least in terms of narrowing down choices? I put together a matrix that can be added to and/or modified to as we get more specimens incorporated into the hatch pages, but even with the limited information provided at present, it seems to show some surprising results. First a few big disclaimers:

1. The photos as a group are admittedly a small sample.
2. Foreshortening and angles in photos affect wing appearance.
3. Some wings stradle the line between description categories.
4. The only species that have multiple representaions of all genders and stages are E. subvaria and E. invaria. More than few remain severely under-represented.

With all this taken into consideration, here's what I think the review showed:

1. Wing shapes seem to come in two broad categories among the most common ephemerillids; they are either elliptical or semi-elliptical towards their apexes. This seems to hold for both forewings and hindwings.
2. No significant wing shape differentiation is shown between gender or stage within a given species.
3. One species (E. subvaria), while consistent in forewing shape (elliptical), shows high variability in hindwing shape across both genders and stages and this doesn't seem to be determinative between them.
4. Species where both hind and forewings are in the same shape category (all semi-elliptical) are E. invaria, both E. dorothea subspecies and the Attenella genus.
5. Species where the shapes are mixed are E. needhami, E. tibialis, and most of the Drunellas.
6. The only member of the Ephemerella genus showing a strong elliptical shape in the forewing looks to be subvaria (though some come close). The rest that show this trait in the photos are all Drunellas.

I have always noticed variability in wing shape among ephemerellids but never given much thought to its significance before. I'm hoping this post will spur some discussion on the topic.

Best regards,

Kurt

I found about one sentence on these in Gonzo's book, and haven't seen them mentioned anywhere else in fly fishing literature. Nor is any of the scientific literature I have on them particularly interesting (just descriptions). Now that I've collected a few and see what unique-looking nymphs they've got, I'm really curious about them.

Do any of you entomologist types know the true color of the PMD spinner? Dorothea or excrucians. Where I fish in MT there are huge spinner falls, many spents are on the water in the morning and others fall again at various periods during the day. I'd like to tie some with egg sacks as I saw many in July but forgot what color they were. Thanks.

The paper is in press now, so I can share an updated taxonomic synopsis of the "unimportant" genus Caudatella. Have fun.


Caudatella edmundsi (Allen, 1959)

Caudatella columbiella (McDunnough, 1935), comb. n.
= Ephemerella californica Allen and Edmunds, 1961, stat. n., syn. n.

Caudatella heterocaudata (McDunnough, 1929)
= Ephemerella circia Allen and Edmunds, 1961, stat. n., syn. n.

Caudatella hystrix (Traver, 1934)
= Ephemerella spinosa Mayo, 1952
= Ephemerella cascadia Allen and Edmunds, 1961

Caudatella jacobi (McDunnough, 1939)
= Ephemerella orestes Allen and Edmunds, 1961