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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

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

27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Stonefly Species Isoperla baumanni (Yellow Sallies)

Species Range

Identification

Source: The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species

Diagnosis. Male larvae of Isoperla bifurcata are most similar to Isoperla acula and can be separated by having fine silky setae sparse on dorsal surface of femora, numerous but not continuous on tibia (Fig. 20 d), and abdomen without a distinct median dark stripe (Fig. 6 d).Source: The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species

Diagnosis. The 5 – 7 submarginal (A) setae of Isoperla baumanni male larvae (Figs. 5 g-h) are most similar to Isoperla sobria (Hagen) and Isoperla tilasqua but differs from Isoperla miwok with only one submarginal (A) seta (Fig. 11 g). The setae counts alone were not sufficient to separate the three species with multiple close set submarginal (A) setae; Isoperla sobria with 3 – 4 submarginal (A) setae (Figs. 17 e, g-h) and 2 - 5 submarginal (A) setae for Isoperla tilasqua (Figs. 19 e, g-h). The basal segments 2 – 3 of the maxillary palpi have long, thin, apically rounded setae (Fig. 5 e Inset) which are shared by Isoperla tilasqua (Fig. 19 e Inset); Isoperla sobria has long thin, apically pointed setae (Fig. 17 e Inset). The variably shaped and large Isoperla baumanni interocellar light area is completely enclosed by dark pigment (Fig. 5 a), similar to Isoperla sobria (Fig. 17 a), but the latter is usually an inverted V shape (or sometimes a very small light spot). The interocellar light area of Isoperla tilasqua (Meacham Creek, Oregon population) is not completely enclosed by dark pigment, and continues past the posterolateral ocelli to the median base of the dorsal head capsule (Fig. 19 a). The light M shaped dorsal head pattern of Isoperla tilasqua is a continuous line, but is interrupted in Isoperla baumanni and Isoperla sobria. A median longitudinal light band is present in all three species, but this line is approximately half as wide as the median base of the light M pattern in Isoperla tilasqua (Fig. 19 a).

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Source: The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species

(Figs. 1 a-d, 2 c, 5 a-h, 20 c)

Source: The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species

Male larva. Body length of mature larva 9 – 10 mm. Dorsum of head with contrasting pigment pattern and fine dark clothing setae, anterior frontoclypeus margin unpigmented; light M shaped pattern anterior to median ocellus usually connected to light frontoclypeus area by an apically narrowed median longitudinal light band, its width at mid length approximately equal to the width at base, lateral arms with irregular margins usually disconnected from median light band, directed posterolaterally, and extending to antennal bases; posterior ocelli with partially enclosed large light areas along outer lateral margins; interocellar area partially light, completely enclosed by dark pigment, light area extending past posterior ocelli, not reaching dark pigment below the arms of the epicranial suture, light area generally oval shaped with acutely constricted base; occiput with irregular spinulae band extending from below eye to near median epicranial suture, completely enclosed by dark pigment (Figs. 1 d, 5 a). Lacinia bidentate, total length 1069 – 1256 µm (Figs. 1, 2 c, 5 e- h, Tables 2 - 4); submarginal row (A + B) with 7 – 10 setae, groups A-B interrupted by gap below subapical tooth (SAT) inner margin (Fig. 5 g); 5 – 7 submarginal setae (A) in a close set row beginning at base of apical tooth (AT), ending before reaching SAT inner margin, row usually single, rarely 2 setae thick, plus 1 thin marginal setae (TMS) adjacent to AT inner margin, sometimes obstructed from view by the AT, submarginal setae (A), or broken, and 1 dorsal seta (DS) located below SAT inner margin, sometimes obstructed from view by SAT, submarginal setae (B), or broken (Fig. 5 h); 2 – 4 submarginal setae (B) located past SAT inner margin (Figs. 5 g-h); 15 – 27 marginal setae (C) initially long stout and widely spaced, usually several setae near end of row arranged in pairs protruding at dorsal and ventral angles, last few shorter and closer, blending into and difficult to differentiate from dorsal surface setae (Fig. 5 e); 38 – 71 ventral surface setae (D) scattered below submarginal and marginal setae, ending posteriorly at approximately ¾ the inner lacinia margin length, occasionally a few setae below submarginal row striated (Fig. 5 f); dorsal surface setae (DSS) forming dense, laterally protruding, longitudinal band, concentrated at junction with marginal setae (C), ending at approximately ½ or a little more the lacinia length (Fig. 5 e). Galea with 15 – 33 setae in sparse ventral row, apex with 2 – 3 setae. Maxillary Palp segments 2 – 3 with curved apically rounded setae (Fig. 5 e Inset). Pronotum with broad median light area bordered by thick dark comma shaped bands typical of the Isoperla sobria complex; discs each with thick black clothing setae, those along median margins usually enclosed by indistinct light brown pigment, lateral margins with broad light bands (Fig. 5 b). Mesonotum and metanotum with contrasting pigment pattern and fine dark clothing setae (Fig. 5 c). Legs with numerous fine golden clothing setae and scattered erect spines on outer surface of femora, erect spines longest and concentrated along dorsal surfaces; fine silky setae sparse on dorsal surface of femora, numerous and continuous on tibia (Fig. 20 c); tibia with faint transverse bands near proximal end. Abdominal terga with three longitudinal dark stripes; wide light median longitudinal band bisected with thin light brown median longitudinal stripe present on distal segments; lateral pair of dark longitudinal stripes about twice as wide as median dark stripe, extending to lateral margins; numerous fine dark clothing setae and erect spines scattered dorsally; posterior margin with scattered long and numerous short spines in a concentrated row (Fig. 5 d).

Source: The Isoperla Of California (Plecoptera: Perlodidae); Updated Male Descriptions And Adult Keys For 18 Western Nearctic Species

Male. Aedeagus: sclerotized posterior process absent; body with one posterobasal lobe, one posteromedian lobe and expanded apex, apex deeply inverted (Fig. 3 a); one large patch of spinulae concentrated below posteromedian lobe (Fig. 3 b), and a long thin patch along posteroapical margin (Fig. 3 c). Abdominal terga 8 - 9, 9, 9 - 10: without stout spinulae or long stout setae. Posterolateral margins of at least abdominal segment 8 with scale-like setae clustered in brushes of several setae. Paraprocts: curved dorsally, length if straightened subequal to first cercal segment, tapering abruptly to blunt apices (Fig. 3 c). Vesicle: rounded lobe, widest at base with broadly rounded apical margin (Fig. 3 d).


Start a Discussion of Isoperla baumanni

Stonefly Species Isoperla baumanni (Yellow Sallies)

Species Range
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