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

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

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington
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.
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.
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Mayfly Species Siphlonurus phyllis (Gray Drakes)

Species Range

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.

Male Spinner

Body length: 12-13 mm
Wing length: 13-14 mm

A rather large species having a conspicuous dark ventral stripe.

Head and thorax blackish brown. Thorax with yellowish shadings on the anterior portions. Legs dull olive brown; femora with apical brown bands. Wings hyaline, faintly tinged with brown in the basal area. Veins dark.

Abdomen dark brown dorsally. Dark oval spots and lateral triangles present. The pale anterior triangles are yellow, this color extending along the lateral margin. Ventrally yellowish. A brown mid-ventral stripe is present, and two small brown dots in each sternite, touching the median stripe. Anterior to the small dots, and laterad of them, are two large brown dots. Light brown shading along the lateral margin, in place of the usual lateral patches. Sternite 9 largely pale yellow, diffusely shaded with brown in the median area; a deep brown lateral streak on each side. Postero-lateral edge of sternite 9 produced into a prominent sharp tooth or spine. Forceps base squarely truncate on its apical margin. Forceps pale yellowish. Tails whitish. Genitalia as in fig. 123.


The nymph of this species has double gills, on each gill-bearing segment of the abdomen. The legs are banded, and the tail has the usual black band beyond the middle.

Specimens of the Mayfly Species Siphlonurus phyllis

2 Nymphs

Start a Discussion of Siphlonurus phyllis


Mayfly Species Siphlonurus phyllis (Gray Drakes)

Species Range
Common Names
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