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Stoneflies - Plecoptera: Perlidae of Gunnison County, Colorado

Nymph key to Genera and species

1a. Occiput with transverse row of evenly spaced spinules; Abdominal terga with numerous spinules.
1b. Occiput with sinuate or incomplete row of spinules; Abdominal terga without spinules.
2a. Occiput with sinuate and irregularly spaced row of spinules; Abdominal terga with few or no intercalary spinules.
2b. Occiput with few scattered spinules near the post ocular fringe; Cerci with long fringe of silky setae.
Only a few scattered spinules behind the eyes. The longer setae (hairs) by the eye are the "postocular fringe". All our perlids have a postocular fringe so its not useful for separating the species.

References

Keys and illustrations modified from the following:
Stark,BP; Gaufin,AR 1976 The nearctic genera of Perlidae (Plecoptera). Miscellaneous Publications of the Entomological Society of America 10, 1-80.
Baumann,RW; Gaufin,AR; Surdick,RF 1977 The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.

Good Links

Key to Perlidae Females
Key to Perlidae Males
Brown, Wendy S. 2004 Plecoptera or Stoneflies of Gunnison County, Colorado
www.gunnisoninsects.org