Mayfly ID?

Taxon

Moderator
Staff member
#1
This gorgeous mayfly was photographed by an acquaintance on April 29, 2012, near the Touchet River in SE Washington. Let's see if you identify it, either by common name, or by family, or by genus, or by lifestage (dun or spinner), or by sex (male or female). Guesses are okay. Each will receive a prompt and respectful response. If this mayfly proves difficult to identify, additional clues will be provided.

 

Old Man

Just an Old Man
#3
Whats the difference between a Male and a Female. Don't they both look a like.

I'm kind of dumb about insects in general. When I fish I just grab something that looks like a fish would like and start fishing. If it doesn't get their attention I change to something else.
 

Taxon

Moderator
Staff member
#4
Roger,
I would say it's a male March Brown (Rhithrogena) dun. Beautiful photo.
Hi Preston-

Thank you for responding. Although you are correct concerning the sex, somewhat surprisingly, the common name for this guy is not March Brown, nor is the genus Rhithrogena. Time to dig out some books. ;)

CORRECT IDENTIFICATIONS:
Common name:
Family:
Genus:
Lifestage:
Sex: male (Preston)
 

Taxon

Moderator
Staff member
#5
Whats the difference between a Male and a Female. Don't they both look a like.
Hi Old Man-

Good question. Most mayfly nymphs cannot easily be identified to sex from a photo. However, mayfly subimagos (duns) and imagos (spinners) can usually be identified to sex from a decent macro photo.

The most obvious clues are the size of the eyes, and the presence of claspers. The males usually have much larger eyes that the females, and males have claspers at the end of their abdomen (which look like calipers). Also (although this doesn't apply to duns), male spinners usually have extremely long fore (front) legs, as compared to the respective female spinners.
 
#6
Roger,

Some barely edjumacated guesses:

Common Name: Pale Evening Dun
Family: Heptageniidae
Genus: Heptagenia
Lifestage: Dun
 

Taxon

Moderator
Staff member
#9
Roger,

Some barely edjumacated guesses:

Common Name: Pale Evening Dun
Family: Heptageniidae
Genus: Heptagenia
Lifestage: Dun
Hi Matt Baerwalde-

You are correct concerning the lifestage, as it is a dun. However, it is not a Pale Evening Dun, nor is it of family Heptageniidae, nor is it of genus Heptagenia.

CORRECT IDENTIFICATIONS:
Common name:
Family:
Genus:
Lifestage: dun or subimago (Matt Baerwalde)
Sex: male (Preston)
 
#14
Genus amaletus?
. Time to dig out some books.
Speaking of which, what would be recommendations for a couple of (very good/very best) books for the NW?--Oregon and WA specifically, but ID, MT, CO, etc. wouldn't hurt. And yes, I'll need pictures in those books. ;)