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Stoneflies - Plecoptera: Nemouridae of Gunnison County, Colorado
Female key to Genera

1a. Cervical gills present.
1b. Cervical gills absent.
2a. Cervical gills highly branched.
2b. Cervical gills simple, never more than four branches.
Nemourinae (in part) Zapada

3a. Some cervical gills branch midway out their length; Eight sternum sclerotized along median notch only.

(Gills have a Y-shape)

3b. Cervical gills branch from base at the neck; Eighth sternum with sclerotized vaginal lobes.
4a. Eighth sternum with distinct sclerotized median stripe.
4b. Eight sternum without distinct sclerotized pattern.

Good Links

Key to Nemouridae Nymphs
Key to Nemouridae Males


Keys and illustrations from the following publications were altered to construct this key:
Baumann,RW; Gaufin,AR; Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.
Stewart,KW; Harper,PP 1996: Plecoptera. In: An Introduction to the Aquatic Insects of North America. 3rd ed. Eds: Merritt,RW; Cummins,KW Kendall/Hunt Publishing Company, Dubuque, Iowa, 217-266.
Ward,JV, Kondratieff,BC and Zuellig,RE 2002: An Illustrated Guide to the Mountain Stream Insects of Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 219 pages.
Brown, Wendy S. 2004 Plecoptera or Stoneflies of Gunnison County, Colorado

Updated 2May2004