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Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Identification: Key to Species of Drunella Nymphs

Option 1Option 2
Western North American speciesEastern North American species
Remaining species:
Drunella coloradensis
Drunella doddsii
Drunella flavilinea
Drunella grandis
Drunella pelosa
Drunella spinifera
Remaining species:
Drunella allegheniensis
Drunella cornuta
Drunella cornutella
Drunella lata
Drunella tuberculata
Drunella walkeri
5 Example Specimens
3 Example Specimens
Go to Couplet 2 Go to Couplet 7
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Couplet 1

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Western North American species
Couplet 2
Eastern North American species
Couplet 7
Abdominal sterna with prominent friction disc of setae
Couplet 3
Abdominal sterna without prominent friction disc of setae (although felt of setae may be present)
Couplet 4
Forefemur with margins toothed
Forefemur with margins smooth
Forefemur with margins with prominent teeth ; Prosternum with no anterior projection
Couplet 5
Forefemur with margins mostly smooth ; Prosternum with prominent anterior projection
Couplet 6
Abdominal terga with paired, narrow spines
Abdominal terga with paired, broadly triangular spines Dorsal abdominal tubercles on a Drunella flavilinea nymph (example boxed in red).
Abdominal terga 8 and 9 with paired spines more than twice the length of spines on preceding segments
Abdominal terga 8 and 9 with paired spines clearly less than twice the length of preceding pairs
Abdomen without paired dorsal tubercles, but may have paired ridges ; Head smooth, without paired occipital tubercles (pictured yellow box) Median ocellar tubercle (red box) and frontoclypeal projections (green boxes)
Couplet 8
Abdomen with paired dorsal tubercles, always well-developed on segments 5-7; Head roughened, with paired occipital tubercles, or with small to large paired occipital tubercles
Couplet 10
Apex of tibial projection sharp and curved ; Frontoclypeals projection are short, flat, and do not protrude anteriorly from the surface of the frontoclypeus (Funk et al. 2008); Median ocellar tubercle relatively small (Funk et al. 2008)
Apex of tibial projection blunt to moderately sharp and straight ; Frontoclypeal projections are longer, conical (or curved), and protrude anteriorly from the surface of the frontoclypeus (Funk et al. 2008) Median ocellar tubercle (red box) and frontoclypeal projections (green boxes) ; Median ocellar tubercle relatively large (Funk et al. 2008)
Couplet 9
Mature nymph 7.8-11.4 mm long (Funk et al. 2008); Median ocellar tubercle sharp and relatively long (red box) Median ocellar tubercle (red box) and frontoclypeal projections (green boxes) ; Lateral frontoclypeal projections usually semilunar (green boxes above); Middle and hind tibiae relatively long (Funk et al. 2008)
Mature nymph 6.4-8.5 mm long (Funk et al. 2008); Median ocellar tubercle blunt to moderately sharp and relatively short; Lateral frontoclypeal projections moderately curved to straight Figure source: Allen & Edmunds (1962) ; Middle and hind tibiae relatively short (Funk et al. 2008)
Larvae have short, marginal, hairlike setae on the heads, legs, and tergites; No long setae protruding dorsally from tergites 8 and 9; Relatively many denticles on tarsal claws, and positioned along the length of the claw
Drunella allegheniensis
Marginal setae not well developed on the heads, legs, and tergites; Long setae protrude dorsally from the anterior margins of tergites 8 and 9; Relatively few denticles on tarsal claws, positioned basally
Couplet 11
Has a row of long, hairlike setae along the margin of the clypeus; More robust, less flattened general appearance; Almost always has a pair of prominent, paired, stout, suboccipital spines
Lacks a row of long, hairlike setae on the clypeus; Usually a very flattened general appearance; Sometimes has only small bumps, other times more prominent suboccipital spines

References

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