Salmonflies
Pteronarcys californica
The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
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Mayfly Family Heptageniidae (March Browns, Cahills, Quill Gordons)
Known as the "clinger" mayflies to anglers, a few species of this family can be extremely prolific, with a lot more that aren't. These lesser species account for many of the curious mayflies you find that never seem to associate with a major hatch, let alone a fishable one. Not all heptageniid species are so scarce though; there are superhatches too.
Heptageniids can be broken into "groups" of similar genera (based on angling concerns) to help keep track of them. Although many of them are closely related, they are not officially divided in this way by entomologists. Here are the groups:
The genus Stenonema, who's Latin name was one of the first etched in the minds of anglers, was for a while largely reclassified into Maccaffertium but has since been reinstated. It includes the March Brown (S. vicarium) and Gray Fox (previously S. fuscum) superhatches.
The Stenonema species are for all practical purposes limited to the East and Midwest.
While Heptagenia has held on to several species, many of its fishable hatches have been moved to the genera Leucrocuta, Nixe, and Ecdyonurus. Some species of Nixe were subsequently moved to Afghanurus. There are many former Heptagenia species across the continent, but few are important to anglers. Of those, more are in the West than in the East.
The closely related genera Epeorus and Ironodes are among the only mayflies to have just two tails as nymphs. Good populations can be found in the West, but it's in the East where the mayfly named after the man that brought the dry fly to America can be found, the superhatch Epeorus pleuralis or Quill Gordon.
The genus Rhithrogena can be identified by the gills of its nymphs. They extend underneath the abdomen in the front and the back. They are very important for early season anglers in the West, but not very often in the East. For western anglers, it's duns are the blotchy winged equivalent of the East's March Brown (Maccaffertium vicarium). Ironically, it is only the Western March Brown that is in the same genus as the English species for which the common name originated.
The genus Cinygmula is easily distinguished by the nymph's enlarged palpi (mouth parts) that stick out from both sides of their heads like little blunt horns. They rarely produce fishable hatches, and none are of much significance except for a few species, mostly in certain locales of the West.
Heptageniids can be broken into "groups" of similar genera (based on angling concerns) to help keep track of them. Although many of them are closely related, they are not officially divided in this way by entomologists. Here are the groups:
Stenonema (blotchy wings)
The genus Stenonema, who's Latin name was one of the first etched in the minds of anglers, was for a while largely reclassified into Maccaffertium but has since been reinstated. It includes the March Brown (S. vicarium) and Gray Fox (previously S. fuscum) superhatches.
The Stenonema species are for all practical purposes limited to the East and Midwest.
Former Heptagenia (plain wings)
While Heptagenia has held on to several species, many of its fishable hatches have been moved to the genera Leucrocuta, Nixe, and Ecdyonurus. Some species of Nixe were subsequently moved to Afghanurus. There are many former Heptagenia species across the continent, but few are important to anglers. Of those, more are in the West than in the East.
Epeorus (two-tailed Nymphs, plain wings)
The closely related genera Epeorus and Ironodes are among the only mayflies to have just two tails as nymphs. Good populations can be found in the West, but it's in the East where the mayfly named after the man that brought the dry fly to America can be found, the superhatch Epeorus pleuralis or Quill Gordon.
Rhithrogena (suction cup gills)
The genus Rhithrogena can be identified by the gills of its nymphs. They extend underneath the abdomen in the front and the back. They are very important for early season anglers in the West, but not very often in the East. For western anglers, it's duns are the blotchy winged equivalent of the East's March Brown (Maccaffertium vicarium). Ironically, it is only the Western March Brown that is in the same genus as the English species for which the common name originated.
Cinygmula (horn heads)
The genus Cinygmula is easily distinguished by the nymph's enlarged palpi (mouth parts) that stick out from both sides of their heads like little blunt horns. They rarely produce fishable hatches, and none are of much significance except for a few species, mostly in certain locales of the West.
Family Range
Hatching behavior
Many heptageniid mayflies emerge from their nymphal shucks on the stream bottom or during their rise to the surface. Others hatch in the surface film. Others still migrate to the shallow margins and use any of the three ways. All of this may depend on habitat and current conditions as much as differences between species. Read about the species you need to match for more details, but there is no substitute for astute observation streamside.
Nymph biology
The Heptageniidae family contains the angler's "clinger" type mayfly nymphs commonly referred to as "Flat Heads" by entomologists. They sport flattened profiles, blunted broad heads, and stout legs suitable for life in fast water. Their flattened tear drop shape is a "miracle" of nature's hydrodynamic engineering employing the same principles used by Formula One race cars to hug the road and reduce wind resistance.Identification
To determine whether a specimen of Ephemeroptera belongs to Heptageniidae, use the Key to Families of Mayfly Nymphs or Key to Families of Mayfly Duns and Spinners.
Specimens of the Mayfly Family Heptageniidae
15 Male Duns
Identification of this one was as follows. Body 9 mm, wing 11 mm.
Both Epeorus albertae and Epeorus dulciana should have a conspicuously darkened humeral crossvein in the forewing. This one doesn't.
The foretarsal claws are dissimilar (one sharp, one blunt), which also rules out the Epeorus albertae group.
The dark macula on the forefemora rules out Epeorus deceptivus, which is also supposed to be a little bit smaller.
Both Epeorus grandis and Epeorus permagnus should be much, much larger.
Of the species known to be present in Washington, this leaves only Epeorus longimanus, which is exactly the right size. The key to male spinners in Traver (1935) describes distinctive markings that are visible (although more faintly) in this dun: “Black posterior margins of tergites do not extend laterally to pleural fold, but an oblique black line form this margin cuts across poster-lateral triangle to pleural fold.”
Both Epeorus albertae and Epeorus dulciana should have a conspicuously darkened humeral crossvein in the forewing. This one doesn't.
The foretarsal claws are dissimilar (one sharp, one blunt), which also rules out the Epeorus albertae group.
The dark macula on the forefemora rules out Epeorus deceptivus, which is also supposed to be a little bit smaller.
Both Epeorus grandis and Epeorus permagnus should be much, much larger.
Of the species known to be present in Washington, this leaves only Epeorus longimanus, which is exactly the right size. The key to male spinners in Traver (1935) describes distinctive markings that are visible (although more faintly) in this dun: “Black posterior margins of tergites do not extend laterally to pleural fold, but an oblique black line form this margin cuts across poster-lateral triangle to pleural fold.”
For details about the tentative identification of this male dun, see the page for associated male spinner, captured from a mating swarm in the same location and at the same time as this dun was emerging.
This pretty little dun was part of a sparse midsummer evening hatch on a large Catskill river.
I could not identify it by following a species key step by step, but I tentatively keyed it to the genus Nixe, and based on distribution maps and physical descriptions the most likely species is Nixe inconspicua. (Edit in 2023: this species was recently moved from Nixe into Afghanurus.)
I could not identify it by following a species key step by step, but I tentatively keyed it to the genus Nixe, and based on distribution maps and physical descriptions the most likely species is Nixe inconspicua. (Edit in 2023: this species was recently moved from Nixe into Afghanurus.)
The lack of a darkened humeral crossvein rules out Epeorus albertae and Epeorus dulciana. The lack of a dark macula on the forefemora rules out Epeorus longimanus. The small size rules out Epeorus grandis and Epeorus permagnus. That leaves as the only possibility known in Washington state Epeorus deceptivus. It is a small species, although not reportedly quite as small as this specimen. I couldn't find anything in the species description in Traver (1935) to definitively confirm or rule out the species ID, given that I don't have the preserved specimen to check under a microscope, but it has to be either deceptivus or something not yet reported in Washington.
It was collected at the same time as a similar-sized female dun.
It was collected at the same time as a similar-sized female dun.
I collected this male dun with a female dun and a female spinner of the same species. Identification was initially difficult because I didn't catch a male spinner, and this dun was missing its legs. I was able to tease the spinner's penes out of the dun's shuck after it expired, although the shape was pretty similar. Fortunately, the shape is a distinctive match to the Epeorus albertae species group. In the key in Needham et al (1935), it keys to Epeorus youngi, which is now considered a synonym of albertae. It's also a very plausible dun version of this spinner collected a few years earlier, a few drainages to the north, at a similar time of year. Additionally, the female dun and spinner collected with this one match very closely those I've collected in the past.
This dun emerged from a nymph in one of the bowls on my table while I was sorting. I photographed it with the nymphal shuck, and it seems to be of the same species as a nymph I photographed from the same sample.
I kept this specimen after photographing it and it molted into a spinner in perfect condition, which I photographed here.
I collected this mayfly on the same trip as a female of the same species. After these photos it molted into a spinner. This is the form of Stenonema vicarium which anglers call the "Gray Fox."
This dun hatched out from a nymph in my aquarium on July 16th, after being collected July 10th. It is probably of the same species as this nymph, and this dun which also hatched from one of these seemingly identical nymphs.
This Epeorus dun managed to emerge successfully even though it had apparently long several legs at some point and only partially grown them back.
I collected this male dun together with a female.
15 Female Duns
I collected this female dun with a male dun and a female spinner of the same species.
I was surprised by the olive cast on the body of this female Rhithrogena dun, which led me to mistake it for a western green drake (Drunella) in the field. I was pleasantly surprised to get a closer look and find something I hadn't collected yet. Its species ID is based on proximity to male spinner collected on the same trip, as well as physical similarity (size, tergite coloration, dark streaks on the femora) to that specimen.
I'm calling this one Cinygmula just based on the general look and the fact that the genus is very common in this river. Official keys can't rule out other Heptageniidae, though.
I'm guessing this one is Rhithrogena virilis based on collection of a male spinner of similar size and body configuration during the same trip.
This female looks very much like a male I collected a few hundred miles away a few days later, so I'm guessing it's the same species, which I believe is Maccaffertium mediopunctatum.
Here's a classic March Brown dun from the Catskills.
This female dun emerged from a creek loaded with mature Cinygmula nymphs including this specimen, so they're probably the same species. Unfortunately there aren't species keys for either stage.
This dun is almost certainly of the same species as this nymph, as it hatched in my cooler from a nearly identical nymph.
This dun comes from the same location, and is about the same size, so is presumably the same species as this male spinner.
I found this dun on the same piece of stream as a similar spinner, probably of the same species.
15 Male Spinners
Although I could not find the preserved specimen to examine under my good new microscope, I'm tentatively calling it one Rhithrogena hageni, based on apparent similarity to this specimen, which I was able to positively ID.
The relative angle of the penes is a bit shallower in this specimen, but I photographed another specimen from the same collecting trip (and I think even the same swarm, although I don't recall for sure) as the other one, and it had the shallower angle seen on this specimen. I'm guessing it's just variation within the species.
The relative angle of the penes is a bit shallower in this specimen, but I photographed another specimen from the same collecting trip (and I think even the same swarm, although I don't recall for sure) as the other one, and it had the shallower angle seen on this specimen. I'm guessing it's just variation within the species.
The identification of this specimen is not positive because some of the key characteristics conflict. The uniform amber tint of the wings and the rusty-colored mid-ventral markings on some of the abdominal sternites point to Cinygmula uniformis, but I could not locate the small ventral subapical spines on the penes that are supposed to also diagnose that species (the ones visible in the pictures aren't the ones I'm talking about). If I prioritize that characteristics, this would probably be Cinygmula mimus, but then the wing and sternite shading/markings are wrong.
This specimen was one of several males fluttering around over the river late in the afternoon near the Twin Falls trailhead on May 14. It's pretty clearly the same species as this one collected on June 22 five years earlier.
I also collected a nymph of presumably the same species in the riffle beneath these dancing males.
I also collected a nymph of presumably the same species in the riffle beneath these dancing males.
This one was very puzzling to identify. It's clearly Heptageniidae. It keys pretty easily to couplet 58 in Merritt, Cummins, & Berg 5th Edition, but that's where things get tricky.
58: Male penes distinctly L-shaped; Segment 1 of foretarsi usually 1/3 to 2/3 the length of segment 2
58': Males penes not distinctly L-shaped; Segment 1 of foretarsi usually 1/5 to 1/2 the length of segment 2
The characteristics conflict here, as I'd say the penes ARE L-shaped, but the fore tarsal ratio is less than 1/3. Maybe the weasel word "usually" allows for that, and it's some kind of Stenonema, for which I'm not aware of any records in Montana, let alone western Montana.
Going by the tarsal ratio and assuming it's not Stenonema, everything in couplet 60 points to Afghanurus: contiguous compound eyes, genitalia similar to fig 13.222 in MC&B, and weakly developed basal costal crossveins in the forewings. But I looked up the original descriptions of the three Afghanurus species, and the body sizes (flowersi 5-7 mm, inconspicua 4 mm, joernensis 6-7 mm) are way below this one's 10 mm.
This led me to notice that the closely related Ecdyonurus is not included in the key at all, so I checked the descriptions of those species and found that Ecdyonurus criddlei fits very well: the color of the legs, the markings on the tergites and sternites, the short fore tarsus and ratios of the segments, etc. It was originally described as 7 mm, smaller than the 10 mm body of this specimen, but synonyms have been described with larger sizes including wing lengths up to 11 mm for females for Heptagenia salvini.
This specimen was found with a female nearby, which I think is probably the same species, although it is difficult to be certain.
58: Male penes distinctly L-shaped; Segment 1 of foretarsi usually 1/3 to 2/3 the length of segment 2
58': Males penes not distinctly L-shaped; Segment 1 of foretarsi usually 1/5 to 1/2 the length of segment 2
The characteristics conflict here, as I'd say the penes ARE L-shaped, but the fore tarsal ratio is less than 1/3. Maybe the weasel word "usually" allows for that, and it's some kind of Stenonema, for which I'm not aware of any records in Montana, let alone western Montana.
Going by the tarsal ratio and assuming it's not Stenonema, everything in couplet 60 points to Afghanurus: contiguous compound eyes, genitalia similar to fig 13.222 in MC&B, and weakly developed basal costal crossveins in the forewings. But I looked up the original descriptions of the three Afghanurus species, and the body sizes (flowersi 5-7 mm, inconspicua 4 mm, joernensis 6-7 mm) are way below this one's 10 mm.
This led me to notice that the closely related Ecdyonurus is not included in the key at all, so I checked the descriptions of those species and found that Ecdyonurus criddlei fits very well: the color of the legs, the markings on the tergites and sternites, the short fore tarsus and ratios of the segments, etc. It was originally described as 7 mm, smaller than the 10 mm body of this specimen, but synonyms have been described with larger sizes including wing lengths up to 11 mm for females for Heptagenia salvini.
This specimen was found with a female nearby, which I think is probably the same species, although it is difficult to be certain.
I collected numerous spinners from a thick dusk mating swarm and spinner fall over the Cedar River on a cloudy evening at the end of June. Duns were emerging at the same time, so I was able to collect several male spinners as well as a female spinner, a male dun, and a female dun of the same species, whatever it is. The microscope pictures here come from a mix of those different males, but all the macro DSLR photos are of the same individual.
This one is difficult to identify, though I went into a lot of detail since I caught so many and their fall really got the fish rising for a while at dusk. The penes have a single set of lateral subapical spines, and the wings of the male spinner appear to be untinted, although there may be a barely-perceptible uniform yellow tint. The two claws at the end of each tarsus are similar to each other in shape. The wing is 7.5 mm long and the body is 7 mm long.
I think these are the possibilities:
1. The best guess is Cinygmula tarda, which is the only species matching the size of this specimen in Needham et al (1935). The rest of the description seems to fit pretty well. However, the picture of the genitalia in that source and the one Slater & Kondratieff (2004) differ somewhat from each other and from this specimen, which more closely fits the drawing for Cinygmula mimus.
2. My next guess would be Cinygmula tioga. The original description in Mayo (1952) fits remarkably well, and it's only reported to be 1 mm longer than this specimen (within the likely range of natural variation). It hasn't been reported yet from Washington, only California and Oregon, but the sites in north-central Oregon aren't implausibly far from west-central Washington. However, the drawing of the penes suggests that the lateral spine should be longer or located closer to the tip than in this specimen, and that species is also supposed to have yellow-tinged wings. There may be a very faint tinge to this specimen, but it's hard to tell.
3. It could be either a species not yet described or an undescribed variant of a current species.
And here's a quick list of why other local species were ruled out:
mimus — This species is the best match for the genitalia, but it's supposed to be much larger with a wing length of 10-11.5 mm, and it should have clearer tinting to the wings in a particular pattern. However, Mayo (1952) notes that mimus should not have tracheations on the tergites, as this one clearly does, which would make it fit tioga. I'm not sure where tarda falls on that characteristic. Also, Slater & Kondratieff (2004) describe the compound eyes of mimus as contiguous, which doesn't fit this specimen. This specimen also has dark mid-ventral markings on the sternites, which mimus should lack.
uniformis — wing length 10 mm, small ventral subapical spine on penes not present in this specimen,
reticulata — wing length 9 mm, has distinctive wing patterning definitely not present on this specimen.
par — wing length 9-10 mm, penes lack prominent lateral spines, generally shaped wrong, tarsal claws would be dissimilar in par
ramaleyi — wing length 10 mm, penes shape way off
gartrelli — wing length 10 mm, crossveins in costal half of forewing margined with brown (unlike this specimen), penes shape similar being in same group with mimus, but has an extra small spine not present in this specimen
This one is difficult to identify, though I went into a lot of detail since I caught so many and their fall really got the fish rising for a while at dusk. The penes have a single set of lateral subapical spines, and the wings of the male spinner appear to be untinted, although there may be a barely-perceptible uniform yellow tint. The two claws at the end of each tarsus are similar to each other in shape. The wing is 7.5 mm long and the body is 7 mm long.
I think these are the possibilities:
1. The best guess is Cinygmula tarda, which is the only species matching the size of this specimen in Needham et al (1935). The rest of the description seems to fit pretty well. However, the picture of the genitalia in that source and the one Slater & Kondratieff (2004) differ somewhat from each other and from this specimen, which more closely fits the drawing for Cinygmula mimus.
2. My next guess would be Cinygmula tioga. The original description in Mayo (1952) fits remarkably well, and it's only reported to be 1 mm longer than this specimen (within the likely range of natural variation). It hasn't been reported yet from Washington, only California and Oregon, but the sites in north-central Oregon aren't implausibly far from west-central Washington. However, the drawing of the penes suggests that the lateral spine should be longer or located closer to the tip than in this specimen, and that species is also supposed to have yellow-tinged wings. There may be a very faint tinge to this specimen, but it's hard to tell.
3. It could be either a species not yet described or an undescribed variant of a current species.
And here's a quick list of why other local species were ruled out:
mimus — This species is the best match for the genitalia, but it's supposed to be much larger with a wing length of 10-11.5 mm, and it should have clearer tinting to the wings in a particular pattern. However, Mayo (1952) notes that mimus should not have tracheations on the tergites, as this one clearly does, which would make it fit tioga. I'm not sure where tarda falls on that characteristic. Also, Slater & Kondratieff (2004) describe the compound eyes of mimus as contiguous, which doesn't fit this specimen. This specimen also has dark mid-ventral markings on the sternites, which mimus should lack.
uniformis — wing length 10 mm, small ventral subapical spine on penes not present in this specimen,
reticulata — wing length 9 mm, has distinctive wing patterning definitely not present on this specimen.
par — wing length 9-10 mm, penes lack prominent lateral spines, generally shaped wrong, tarsal claws would be dissimilar in par
ramaleyi — wing length 10 mm, penes shape way off
gartrelli — wing length 10 mm, crossveins in costal half of forewing margined with brown (unlike this specimen), penes shape similar being in same group with mimus, but has an extra small spine not present in this specimen
This male was collected at the same time as this female and is likely the same species.
It keys pretty clearly to Rhithrogena undulata using the key in Traver 1935, although the size is larger than expected for that species in that source.
It keys pretty clearly to Rhithrogena undulata using the key in Traver 1935, although the size is larger than expected for that species in that source.
This male was collected from the same cloud of spinners as this female and is probably the same species. I'm tentatively calling them both Cinygmula for now, but I'm really not sure about that ID yet.
I'm fairly sure this is a specimen of Rhithrogena virilis based on closeup examination of the reproductive anatomy under the microscope (not shown in photos). The other other species of Rhithrogena this large is Rhithrogena flavianula, but the key in Needham's Biology of Mayflies mentions annulation in the abdomen (visible in some images on bugguide.net) more distinct than that on this specimen.
The body and front wing were both about 15.5 mm long, while the cerci were 40 mm long.
The body and front wing were both about 15.5 mm long, while the cerci were 40 mm long.
A couple days earlier I caught a male spinner of this species with some wing damage and missing tails, so I went back to the same pool try to get one more intact. This one has some leg damage, but between the two specimens you can get an idea what the whole insect looked like. There were small clouds of Cinygma dimicki spinners again over the same two small, specific locations in the pool, which is an interesting testament to how repeatably they choose their ideal mating habitat. I was able to capture this one and a female.
15 Female Spinners
I collected this female spinner with a male dun and a female dun of the same species.
I only caught a couple of these, and they were both females, so I'm not sure I'll be able to identify it any further.
This one was collected close to a male which, based on size and general structure, was likely the same species. Females are supposed to be lighter-colored and with less distinct markings than the males, although the difference in this pair is particularly stark.
This female spinner was collected with a male from the same swarm.
Although I couldn't key out this female spinner, I'm fairly comfortable calling her Stenonema modestum based on the markings on the abdomen and their similarity to those on the males of this species. This one probably came from the Namekagon River, although there's a possibility it came from the West Fork of the Chippewa River, because it was found in the truck after fishing those streams on back-to-back days.
This one was collected at the same time as this male and is likely the same species.
This female was collected from the same spinner cloud as this male.
For details about the tentative identification of this female spinner, see the page for associated male spinner, captured from the same mating swarm.
I was able to identify this female because I captured her while she was mating with an identifiable male.
This one may look a bit strange, because one of her main wings came off in my container.
15 Nymphs
This specimen is interesting because Heptagenia pulla has not been reported from Washington or neighboring states (Saskatchewan is the closest), yet the distinctive key characteristics are clear. Furthermore, it might even be a species not listed on this site—Jacobus et al. (2014) writes, "the northern and western specimens of H. pulla may in fact be a synonym of the Palearctic species H. dalecarlica Bengtsson (Kjaerstad et al. 2012) and the true H. pulla may be restricted to eastern North America."
It keys to the genus Heptagenia because the tarsal claw has a single basal tooth, and the gills on segment 7 have fibrils.
For the species key in Jacobus et al. (2014):
1. The left mandible is planate, whereas the right mandible is angulate.
2. The labrum is much wider than long.
3. There's a thin light-colored streak lateral to the eye on the head.
It keys to the genus Heptagenia because the tarsal claw has a single basal tooth, and the gills on segment 7 have fibrils.
For the species key in Jacobus et al. (2014):
1. The left mandible is planate, whereas the right mandible is angulate.
2. The labrum is much wider than long.
3. There's a thin light-colored streak lateral to the eye on the head.
This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
Identification notes from the microscope: Gills on segment 1 extend anteriorly below the body, but not all the way to touching; posterolateral spines minor; femora without fuscous macula.
This nymph was one of several mature Cinygmula nymphs collected at the same time as this female dun emerged, so they're probably the same species. Unfortunately there aren't species keys for either stage.
Unfortunately there's no good key to species of Cinygmula nymphs and I didn't find an adult, so this one will have to stay at genus level.
I'm basing the ID of this near-mature nymph on a male spinner with similar size and markings, collected on the same trip. There isn't a key to reliably identify the nymphs of most Rhithrogena species otherwise.
This specimen seems to be of the same species as a dun I photographed which emerged from another nymph in the same sample.
10 Streamside Pictures of Heptageniidae Mayflies:
This is Troutnut.com's first picture of a springtail, a type of six-legged, non-insect arthropod. It's riding on the surface film under the mayfly's left tail.
In this picture: Arthropod Class Collembola (Springtail) and Mayfly Genus Cinygmula (Dark Red Quill).
11 Underwater Pictures of Heptageniidae Mayflies:
In this picture: Mayfly Genus Epeorus (Little Maryatt) and Mayfly Family Baetidae (Blue-Winged Olive).
In this picture: Mayfly Genus Epeorus (Little Maryatt) and Mayfly Family Baetidae (Blue-Winged Olive).
This log houses several Ephemerella mayfly nymphs and, on the top right, an Epeorus mayfly nymph.
In this picture: Mayfly Species Ephemerella invaria (Sulphur) and Mayfly Genus Epeorus (Little Maryatt).
In this picture: Mayfly Genus Epeorus (Little Maryatt) and Animal Class Gastropoda (Snail).
There are a couple Epeorus mayfly nymphs clinging to this rock. One interesting thing I've noticed is that even though the stream has a lot of clingers, they rarely show up in my photos, and I've started paying more attention to the river bottom while I'm fishing I've noticed that clinger nymphs generally see or feel me coming and scurry to the undersides of their rocks before I can get in picture range. I think I have the same problem with stoneflies.
In this picture: Mayfly Genus Epeorus (Little Maryatt).
This is a pretty clear photo of an Epeorus nymph clinging flat against a log. The big mound of debris on the bottom center of the picture, attached to the light rock, is a structure that's been puzzling me. I've found several in one section of the river. It's big, like 2 inches long and maybe 1/2-3/4 inch wide/tall, and hollow, like some sort of coccoon or something. It's clearly a structure built by some sort of little creature, but I'm not sure what.
In this picture: Mayfly Genus Epeorus (Little Maryatt).
Discussions of Heptageniidae
Clinger nymphs are shaped that way to hang in really fast currents. Really?
14 replies
Posted by Entoman on Feb 23, 2013 in the genus Rhithrogena
Last reply on Jun 14, 2017 by Steamntrout
It is commonly held that clingers are flattened to make their lives better adapted to faster water. Their teardrop shape is certainly a classic symbol of aero and hydrodynamic perfection, so there must be some connection, right? It seems to me that such ideas show a complete misunderstanding of the hydraulic reality in which they live. Current is negligable even in the fastest a few mm. from the surface of solid objects. In fact, it is actually quite calm. I've observed baetids clinging by their tippy toes to the tops of rocks in fast riffles with no apparent effort, often next to clinger species that look like they're hanging on for dear life. What if clinger nymphs are flattened not to hold their place in fast currents but rather to facilitate movement in their ecological niche of the cramped spaces under and between cobble or crevices in other substrate types?
It is also thought that the gills of some species form ''suction'' to hold them in place. Since suction is a phenomena of vacuum creation in the atmosphere, how are these nymphs accomplishing this underwater? Is it their ultra delicate gills that hold them in place or a firm claw grip? The horizontal sprawl of the legs masks this as the gills stay in place until the legs brake free. Exposed to the air, the gills seem to laminate against the rock, just as crepe paper would if first held underwater before a rock was lifted out into the air from underneath it. However, underwater their gills behave like the crepe, flowing freely. They are performing their function as gills not suction cups. I find it hard to believe they evolved the way some think merely so they can make it more difficult for humans to pluck them from rocks in the atmosphere. How is it these mighty structures that defy our attempts to pry them from the rocks curiously fall off so easily when prodded for inspection a few seconds later in a tray or jostled in a container on the way home?
Even many scientific papers have encouraged these dubious beliefs so it's not just angler myth... And they go unchallenged... Thoughts?
It is also thought that the gills of some species form ''suction'' to hold them in place. Since suction is a phenomena of vacuum creation in the atmosphere, how are these nymphs accomplishing this underwater? Is it their ultra delicate gills that hold them in place or a firm claw grip? The horizontal sprawl of the legs masks this as the gills stay in place until the legs brake free. Exposed to the air, the gills seem to laminate against the rock, just as crepe paper would if first held underwater before a rock was lifted out into the air from underneath it. However, underwater their gills behave like the crepe, flowing freely. They are performing their function as gills not suction cups. I find it hard to believe they evolved the way some think merely so they can make it more difficult for humans to pluck them from rocks in the atmosphere. How is it these mighty structures that defy our attempts to pry them from the rocks curiously fall off so easily when prodded for inspection a few seconds later in a tray or jostled in a container on the way home?
Even many scientific papers have encouraged these dubious beliefs so it's not just angler myth... And they go unchallenged... Thoughts?
M. ithaca in M. mediopunctatum section?
3 replies
Posted by GONZO on Sep 1, 2012 in the species Stenonema mediopunctatum
Last reply on Sep 4, 2012 by Entoman
Hi Jason,
In this section, the Midwestern nymphs (#573 & #574) with the dark irregular ventral bars across the anterior portion of the sternites look like Maccaffertium mediopunctatum arwini (the Midwestern ssp.), but the two Eastern duns (#733 & #765) and the associated shuck (of #765) and nymph (#764) look more like Maccaffertium ithaca to me.
Three Maccaffertium species can have very similar ventral markings in the nymph—dark, sinuate, chevron-shaped bars on many of the sternites and dark lateral marks (sometimes connected to form an inverted U-shaped mark) on segment 9. The Eastern mediopunctatum subspecies, M. m. mediopunctatum, has these markings, as does M. ithaca. Similar markings also appear as a less-common variant marking of M. modestum (or the M. modestum species complex). However, these species differ in the length and location of posterolateral projections, leg markings, the appearance of the subs and adults, and size.
Although interpretation of posterolateral projections can be tricky, those projections should help to separate the nymph (and husk) from mediopunctatum. On mediopunctatum, projections are usually on segments 3-9, 4-9, or 5-9, and those on 8 and 9 are fairly long. On ithaca, projections are usually on segments 6-9 or 7-9, and those on 8 and 9 are somewhat shorter (when compared to mediopunctatum). The twin brown bands on the femora of the nymphs should also help to separate them from modestum and mediopunctatum (usually three or four in those species).
The brown posterior margins and median dorsal stripes of the duns (similar to those found in M. vicarium) are typical of ithaca. In McDunnough’s original description of mediopunctatum (1926), he mentions that some of his (paratype) specimens were reared from subimagos, and he describes those subimagos as “quite pale whitish in coloration.”
Size might also be somewhat helpful in distinguishing these specimens from M. m. mediopunctatum (about 7-10 mm at maturity) and modestum (about 8-11 mm at maturity). M. ithaca is about 9-14 mm at maturity. The relatively mature nymph (#764) is at least 11 mm, the female dun (#733) is about 13 mm, and the male dun (#765) is about 11 mm.
When all of these factors are considered, it seems to me that M. ithaca is a more likely ID for the Eastern specimens. (See Bednarik and McCafferty 1979 and Lewis 1974.) I would suggest the following placement for specimens currently in this section:
M. ithaca nymph: http://www.troutnut.com/specimen/764
M. ithaca female dun: http://www.troutnut.com/specimen/733
M. ithaca male dun: http://www.troutnut.com/specimen/765
M. mediopunctatum arwini nymph: http://www.troutnut.com/specimen/573
M. mediopunctatum arwini nymph: http://www.troutnut.com/specimen/574
Best,
Lloyd
In this section, the Midwestern nymphs (#573 & #574) with the dark irregular ventral bars across the anterior portion of the sternites look like Maccaffertium mediopunctatum arwini (the Midwestern ssp.), but the two Eastern duns (#733 & #765) and the associated shuck (of #765) and nymph (#764) look more like Maccaffertium ithaca to me.
Three Maccaffertium species can have very similar ventral markings in the nymph—dark, sinuate, chevron-shaped bars on many of the sternites and dark lateral marks (sometimes connected to form an inverted U-shaped mark) on segment 9. The Eastern mediopunctatum subspecies, M. m. mediopunctatum, has these markings, as does M. ithaca. Similar markings also appear as a less-common variant marking of M. modestum (or the M. modestum species complex). However, these species differ in the length and location of posterolateral projections, leg markings, the appearance of the subs and adults, and size.
Although interpretation of posterolateral projections can be tricky, those projections should help to separate the nymph (and husk) from mediopunctatum. On mediopunctatum, projections are usually on segments 3-9, 4-9, or 5-9, and those on 8 and 9 are fairly long. On ithaca, projections are usually on segments 6-9 or 7-9, and those on 8 and 9 are somewhat shorter (when compared to mediopunctatum). The twin brown bands on the femora of the nymphs should also help to separate them from modestum and mediopunctatum (usually three or four in those species).
The brown posterior margins and median dorsal stripes of the duns (similar to those found in M. vicarium) are typical of ithaca. In McDunnough’s original description of mediopunctatum (1926), he mentions that some of his (paratype) specimens were reared from subimagos, and he describes those subimagos as “quite pale whitish in coloration.”
Size might also be somewhat helpful in distinguishing these specimens from M. m. mediopunctatum (about 7-10 mm at maturity) and modestum (about 8-11 mm at maturity). M. ithaca is about 9-14 mm at maturity. The relatively mature nymph (#764) is at least 11 mm, the female dun (#733) is about 13 mm, and the male dun (#765) is about 11 mm.
When all of these factors are considered, it seems to me that M. ithaca is a more likely ID for the Eastern specimens. (See Bednarik and McCafferty 1979 and Lewis 1974.) I would suggest the following placement for specimens currently in this section:
M. ithaca nymph: http://www.troutnut.com/specimen/764
M. ithaca female dun: http://www.troutnut.com/specimen/733
M. ithaca male dun: http://www.troutnut.com/specimen/765
M. mediopunctatum arwini nymph: http://www.troutnut.com/specimen/573
M. mediopunctatum arwini nymph: http://www.troutnut.com/specimen/574
Best,
Lloyd
Stenonema femoratum male spinner
3 replies
Last reply on May 21, 2012 by Entoman
Male Stenonema femoratum collected from the Grand River, Ontario. Note the 3 spots at the hind margins of each of the abdominal segments.
Added more Heptagenia culacantha info
12 replies
Posted by Troutnut on Dec 19, 2006 in the species Heptagenia culacantha
Last reply on Feb 8, 2012 by Entoman
I went to the entomology library today and photocopied the 1985 paper that first described this curious species. I've updated the culacantha page with this information.
Red Heptagenia?
30 replies
Last reply on Jul 23, 2011 by PaulRoberts
The gills and protruding mouthparts make me think that this might be Cinygmula. I've seen red phase Rhithrogena nymphs, but have never seen this coloration in Cinygmula (or Heptagenia).
Start a Discussion of Heptageniidae
References
- Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
- Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.
Mayfly Family Heptageniidae (March Browns, Cahills, Quill Gordons)
Taxonomy
Genus in Heptageniidae
Afghanurus
1
14
Anepeorus
0
0
CinygmaWestern Light Cahills
4
24
CinygmulaDark Red Quills
41
262
EcdyonurusWestern Ginger Quills
3
19
EpeorusLittle Maryatts
58
357
Heptagenia
10
44
Ironodes
1
3
Leucrocuta
11
58
Macdunnoa
0
0
Nixe
0
0
Raptoheptagenia
0
0
Rhithrogena
31
171
Spinadis
0
0
StenacronLight Cahills
8
47
StenonemaMarch Browns and Cahills
66
329
Genus in Heptageniidae: Afghanurus, Anepeorus, Cinygma, Cinygmula, Ecdyonurus, Epeorus, Heptagenia, Ironodes, Leucrocuta, Macdunnoa, Nixe, Raptoheptagenia, Rhithrogena, Spinadis, Stenacron, Stenonema