Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

> > Ephemerella tibialis

The Specimen

Serratella micheneri (Little Western Dark Hendrickson) Mayfly NymphSerratella micheneri (Little Western Dark Hendrickson) Mayfly Nymph View 9 PicturesThis specimen has tarsal claws (Tarsal claw: The claws at the tip of the tarsus, on an insect's "foot.") with 7 denticles (
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
The denticles on the tarsal claw of this Ephemerella nymph are highlighted in red.
Denticle: Small tooth-like projects, often appearing like serrations on the tarsal claws of certain mayfly nymphs.
and tubercles (
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled.  They are especially large in this species.
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.
on abdominal segments 4-7 only. It keys to Serratella micheneri, as do some other specimens from the same collection that lacked the dorsal (Dorsal: Top.) stripe.
Collected July 28, 2019 from Mystery Creek #199 in Washington
Added to by on July 30, 2019

The Discussion

MillcreekDecember 24th, 2019, 7:31 pm
Healdsburg, CA

Posts: 356
This nymph appears to be Ephemerella tibialis formerly known as Serratella tibialis. Check out Allen and Edmunds;

Also check and

Edit: Just noticed the other two Serratella micheneri sets of photos. These also appear to be Ephemerella tibialis.

Also spotted these two sets of photos where you identified the same or a similar nymph as Ephemerella tibialis.
TroutnutDecember 25th, 2019, 8:19 pm
Bellevue, WA

Posts: 2737
I keyed this one under the microscope using a more recent key than Allen and Edmunds:

Jacobus, L. M., N. A. Wiersema and J. M. Webb. 2014. Identification of Far Northern and Western North American mayfly larvae (Insecta: Ephemeroptera), north of Mexico. Joint Aquatic Science meeting, Portland, OR. 176 pp. + suppl. Unpublished workshop manual.

The couplet on page 64 distinguishes E. tibialis from the other species:

81e) Maxillary canines strongly serrate laterally; thoracic nota with small, brown excrescences (sometimes difficult to detect), especially between forewingpads = Ephemerella (Vittapallia) tibialis (very similar to E. nuda)

Maxillary canines not obviously serrate laterally; thoracic nota without small, brown excrescences = 81f

If I'm remembering correctly (and I might not be), I looked pretty hard at the maxillary canines and the thoracic nota under the microscope and couldn't find the characteristics pointing to tibialis. It is a bit odd that I didn't mention that in the captions, though, so perhaps I'm misremembering or I just failed to interpret the characteristics correctly.

The key does describe Serratella as having "Abdominal terga either without tubercles or with relatively large, blunt and somewhat sinuate tubercles", and one of the other specimens I labeled as micheneri seems to have sharper tubercles than those shown in the corresponding illustration in the key.

Perhaps Luke can weigh in?
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
MillcreekDecember 26th, 2019, 8:01 am
Healdsburg, CA

Posts: 356
Found these pictures at Bold. They're not very good quality but may give enough to identify the critters.[tax][tax]

It would be nice to hear from Luke.

Quick Reply

You have to be logged in to post on the forum. It's this easy:
Username:          Email:

Password:    Confirm Password:

I am at least 13 years old and agree to the rules.

Related Discussions

TitleRepliesLast Reply
Re: Ephemerella nymph
In Ephemerella aurivillii Mayfly Nymph by Millcreek
1Sep 26, 2020
by Troutnut
Re: Brown Dun hatch/swarm time?
In the Mayfly Species Ameletus ludens by Konchu
10Apr 30, 2009
by Troutnut
Re: Serratella micheneri nymphs
In the Photography Board by Millcreek
2Oct 13, 2014
by Millcreek
Re: Ephemerellinae
In the Mayfly Family Ephemerellidae by GONZO
7Oct 4, 2008
Re: Emerger
In the Mayfly Genus Serratella by Martinlf
6Jun 11, 2009
Re: Mix-up
In Siphlonurus autumnalis Mayfly Nymph by GONZO
2Jul 2, 2011
by Troutnut
Re: Ephemerella dorothea infrequens ?
(2 more)

In the Identify This! Board by Millcreek
25Jan 8, 2016
by Wbranch
Re: Dobsonfly
In General Discussion by FredH
8Mar 28, 2014
by Taxon
Re: Serratella levis
(2 more)

In the Photography Board by Millcreek
8Mar 20, 2016
by Entoman
Re: Ephemerella maculata
(1 more)

In the Photography Board by Millcreek
3Apr 12, 2015
by PaulRoberts
Most Recent Posts
Re: Are mayflies declining?
In General Discussion by Wiflyfisher (Adirman replied)