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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.

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 Cinygma lyriforme (Western Light Cahills)

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

Described in Needham et al (1935) as Cinygma lyriformis
Body length: 11.5 mm
Wing length: 12 mm

Head brown; clypeus pale; black shading at bases of ocelli. Thorax brown; posterior portion of mesonotum with slight ochreous shading, and yellow line along antero-lateral margin anterior to wing root. Pleura with pale shading at wing roots. Fore femur and tibia light brown; two rather indistinct darker brown bands on femur, apex also darker; base and apex of tibia narrowly blackish brown. Fore tarsus pale greyish, basal joint about 1/2 the length of the second. Femora of middle and hind legs similar to fore femur, tibiae paler. Wings hyaline; veins fine, light brown; cross veins very indistinct, almost colorless, in costal space except at apex of wing; a fine line parallel to and just below the costa divides this apical portion into an upper series of small costal cells and a lower subcostal series of much larger ones.

Abdominal segments 2-7 semi-translucent whitish; posterior margins of tergites deep brown. Traces of a geminate brown mid-dorsal line are present, and lateral triangular extensions from the posterior margin, halfway between mid-dorsal line and pleural fold, reach to about the middle of each tergite. Sternites with a midventral row of small brown spots. Segments 8-10 opaque; tergites light brown, sternites tinged with ochreous brown. Forceps and tails dull brown. Penes distinctly lyre-shaped (see fig. 99).

Differs from Cinygma integrum in the paler abdomen and in structural details of the penes.

Start a Discussion of Cinygma lyriforme


  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Cinygma lyriforme (Western Light Cahills)

Species Range
Common Name
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