Ephemerella	larva (nymph) Copyright © 2011 Kurt Schirmer	subimago (dun) - male Copyright © 2010 imago (spinner) - male Copyright © 2010 Colin M imago (spinner) - female Copyright © 2010 Colin M
Ephemerella	Finger-like max. palps well developed; femora & tails all similar; gills on ab. seg. 3; no disk of hairs on u/s of ab.; sides of ab. seg. 9 don't extended to the tails; tails approx. equal in length; last 2/3 of tails w/bristles extending laterally.	.
Ephemerella alleni
Ephemerella aurivillii
	Top hind edge of (at least) abdominal segments 3-7 w/small to medium tubercles; hind corners of abdominal segment 3 w/points similar to following segments; front of head smooth (no tubercles).	.
Ephemerella dorothea infrequens (Pale Morning Dun; Rusty Spinner; Pale Morning Spinner; PMD. )
	Body uniform brown color, abdomen w/weak, light markings; no abdominal tubercles; points on the sides of segment 4 and 5 are relatively long compared to those of inermis; small oval gills on segs 3-7.	Body cream w/olive cast; wings light gray; length 5.5-7 mm.; 3 tails; emerges May-mid Jul.
Ephemerella excrucians
Ephemerella tibialis (Red Quill; Whitegloved Howdy; Small Dark Hendrickson; Small Western Dark Hendrickson. )
	Abdominal segments 2-8 w/small, sharply pointed tubercles on hind edge; rear edges of middle abdominal segments straight, often w/dorsal stripe down middle of abdomen; dark/light banding on legs.	Body dark reddish brown; wings pale to dark gray; length 7-9 mm.; 3 tails; emerges Aug 1 - Sep 15.
Ephemerella velmae
Ephemerella verruca

State of Washington distribution is based on:
Mayflies (Ephemeroptera) of the far western United States (Part I: Washington) by M. D. Meyer & W. P. McCafferty,
and augmented by A DNA Barcode Library for North American Ephemeroptera: etc. by Webb, Jacobus, Funk, et. al.