Blue-winged Olives
Baetis
Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
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Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
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Identification: Key to Species of Caudatella Nymphs, Couplet 3
Identification: Key to Species of Caudatella Nymphs, Couplet 3
Adapted from Jacobus 2010 (2010)
| Option 1 | Option 2 |
|---|---|
| Cerci approximately two thirds length of median filament | Cerci less than one-half length of median filament |
| Abdominal sterna with solid color, never with longitudinal stripes or other such markings | Abdominal sterna almost always with three dark, longitudinal markings |
| Remaining species: Caudatella columbiella and Caudatella heterocaudata | |
| Caudatella jacobi | Go to Couplet 4 |
Adapted from Jacobus 2010 (2010)
The current couplet is highlighted with darker colors and a icon, and couplets leading to this point have a icon.
Leads to Caudatella edmundsi:
- Maxillary palp vestigial; tarsal claw with two prominent rows of denticles
Leads to Couplet 2:
- Maxillary palp with three distinct segments; tarsal claw with only one distinct row of denticles
Couplet 2
Leads to Caudatella hystrix:
- Paired medial spines on abdominal terga long and curved (at least on middle segments), some almost hook like
Leads to Couplet 3:
- Paired medial spines on abdominal terga relatively straight, none longer than respective segment
Couplet 3
Couplet 3 (You are here)
Leads to Caudatella jacobi:
- Cerci approximately two thirds length of median filament
- Abdominal sterna with solid color, never with longitudinal stripes or other such markings
Leads to Couplet 4:
- Cerci less than one-half length of median filament
- Abdominal sterna almost always with three dark, longitudinal markings
Couplet 4
Leads to Caudatella heterocaudata:
- Cerci approximately one-third length of median filament (about the length of the abdomen)
- Distinct pair of medial spines present only on abdominal terga 2–9, with the spine tips blunt
Leads to Caudatella columbiella:
- Cerci approximately one-sixth length of median filament (about half the length of the abdomen)
- Distinct pair of medial spines present on abdominal terga 1–9, with the spine tips sharp
Start a Discussion of this Couplet
References
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
- Jacobus, Luke M. 2010. Taxonomic Review of the Caudatella heterocaudata (McDunnough) and C. hystrix (Traver) Complexes (Insecta: Ephemeroptera: Ephemerellidae). Psyche: A Journal of Entomology 2010: 1-5.