Mayfly Species Cinygma lyriforme (Western Light Cahills)

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.