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

> > Spinadis simplex

The Specimen

Heptageniidae (March Browns, Cahills, Quill Gordons) Mayfly DunHeptageniidae (March Browns, Cahills, Quill Gordons) Mayfly Dun View 10 PicturesThis specimen is really strange, very different in form from any other mayfly I've seen. Unfortunately it was found alone crippled in an eddy and in pretty bad shape, and I couldn't find any others like it.
Collected June 28, 2005 from the Long Lake Branch of the White River in Wisconsin
Added to by on May 26, 2006

The Discussion

TaxonJuly 19th, 2019, 11:10 pm
Site Editor
Plano, TX

Posts: 1294
Hi Jason-

I believe this female to be a spinner, rather than a dun, and is probably Spinadus simplex.
Roger Rohrbeck
TroutnutJuly 20th, 2019, 7:21 am
Bellevue, WA

Posts: 2542
Hi Roger,

That's an interesting guess and certainly seems to match the general body profile well. However, the color patterns on both the tergites and sternites are very different from those in the Spinadis simplex specimen you uploaded to earlier this year:

Another page on there led to this paper describing the first adult of Spinadis simplex:

This characteristic seems especially relevant in the description of S. simplex, and doesn't seem to match this specimen: "The fore tibia is approximately three times as long as the tarsus, and one-third the length of the femur."

Another important one is, "The hind tibia is 1.16 times the femur length." They note this is also present to some extent in the nymphs.

Also, the shape of the subanal plate is pretty different and is noted as a valuable characteristic.

The paper also extensively describes the characteristics of an enlarged pronotum in S. simplex that doesn't seem to be present in this one.

Finally, the habitat is very different; this came from a smalls stream distant from any of the large rivers previously described as Spinadis habitat.

I still think this is a dun -- the wings are quite pale for a dun but not really hyaline like a spinner. My early photography didn't make this particularly easy to tell, but you can also make out setae on the margins of the wings in this picture.

The dun-spinner difference might explain some other differences including the leg proportions, but I think enough characteristics differ that it's probably not S. simplex.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

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: Timpanoga?
In the Identify This! Board by CalebBoyle
3Apr 5, 2008
by Troutnut
Re: looking for 1999 American Angler issue
In General Discussion by Konchu
19Oct 8, 2010
by PaulRoberts
Re: Puzzled on this mayfly, not even confident on family
In Male Rhithrogena Mayfly Spinner by Troutnut
1Jul 23, 2019
by Millcreek
Distance between the eyes of male Epeorus
In the Mayfly Genus Epeorus by Troutnut
Re: Arctopsyche Grandis
In the Caddisfly Genus Arctopsyche by Epeorus
6Jul 6, 2014
by Entoman
Re: Lepto question
In the Mayfly Family Leptophlebiidae by JasonM
1Mar 7, 2010
by Taxon
Re: A mystery late-season Epeorus
In Male Epeorus frisoni Mayfly Dun by Troutnut
7May 9, 2012
by Entoman
Re: Help to get some specimens of the isopod Caecidotea communis
In the Sowbug Family Asellidae by Leonardo
11Mar 29, 2013
by Leonardo
Re: maccafertium?
In the Identify This! Board by Dryfly
17Jun 2, 2007
by Dryfly
Re: caddis
In the Identify This! Board by Dryfly
8Mar 19, 2007
by DMM
Most Recent Posts
Re: 1wt gear
In Gear Talk by Red_green_h
Re: Changing fly line
In Gear Talk by Red_green_h (Troutnut replied)
Re: Holy Waters - over-rated
In General Discussion by Brian314 (Partsman replied)
Re: 6wt reel help
In Gear Talk by Swampfox (Partsman replied)
Re: Cold weather fly fishing
In Beginner Help by Red_green_h
Re: Boots
In Gear Talk by Martinlf (Wbranch replied)
Re: nm
In Gear Talk by Red_green_h
Re: My (new) place and its environs
In the Photography Board by Jmd123 (Partsman replied)