Mayfly Species Siphlonurus quebecensis (Gray Drakes)

A handsome dark species, with more or less complete dark ventral U-shaped marks.

Head yellowish. Compound eyes purplish grey. Thorax reddish brown; pinkish markings on mesonota and metanota; sutures of pleura widely cream colored. Fore leg of male light reddish brown. Femur with a dark ring at basal joining, and a brown band near apex; apex yellowish. Tibia and tarsus concolorous, brown. Middle and hind legs yellowish; base of femur, apical femoral band, knee and joinings of other segments brown. Last three tarsal joints, and claws, washed with brown.

Wings hyaline. Veins dark purplish brown, except stigmatic cross veins, which are pale brown, almost obsolete along the subcosta. Stigmatic area opaque white. Stigmatic cross veins numerous, anastomosing at the middle of their length. A thickened spot at the bulla, on subcosta, radius and radial sector.

Abdomen dark reddish brown dorsally, with usual pale lateral triangles and dark oval marks. Tergites 8-10 brighter red in color, and with larger pale areas, which are often powdery white. Ventrally whitish, subhyaline. Each sternite typically has the usual dark lateral patches and oblique dark streaks, the latter joined at the anterior margin to form the U-shaped dark mark. Sternites 1-7 pale in the median area, on the posterior margin and the antero-lateral angle. Sternites 8 and 9 largely dark except for a pale median streak in the posterior half. Genitalia pale reddish brown. Penes distinctive in form (see fig. 123). Tails pale yellowish white. Each joining rather widely ringed with purplish brown.

Nymphs have double gills on segments 1 and 2 only. Femur banded near the apex, as in the imago. Tibia with a basal band, tarsus twice banded. Ventral pattern of the abdomen comparable to that of the imago. A wide black band across the tails at about 2/3 of their length.