Mayfly Species Siphlonisca aerodromia (Gray Drakes)

Head brownish; median carina yellow, margined laterally and frontally with black; an oblique black streak below each antenna. Thorax reddish brown. The mesothoracic and metathoracic scutella, the sternum, and oblique streaks on the pleura, very dark red-brown. Fore leg of male reddish brown; tarsi paler than femora and tibiae. Middle and hind legs yellowish. Wings hyaline, strongly tinged with amber, which is most distinct in the male. Venation of the fore wing very dark red-brown; of most of the hind wing, black. Humeral cross vein strong, dark. A few costal and subcostal cross veins before the bulla are narrowly brown-margined. Cross veins of the first three spaces grouped in twos or threes at the bulla. Stigmatic cross veins simple, straight, about 14 in number; not forked nor anastomosed.

Abdomen pale yellowish brown with brown markings. Middle segments semi-translucent; apical segments opaque, washed with yellow. Tergites dark red-brown on the posterior margins, postero-lateral angles, and along the lateral margins; the flaring lateral extensions also dark. Median line pale greyish, narrow on basal tergites, widening progressively on those behind. A wide dark submedian stripe bounds it on either side. Middle sternites narrowly pale on the posterior margins. A dark apical cross band on each sternite, next to the pale posterior margin. Median area washed with reddish brown; bounded on each side by a rather wide darker brown submedian streak arising from the posterior margin, and extending forward almost to the anterior border. Each streak ends in an oval dark brown spot. Forceps base yellowish, with two longitudinal reddish brown stripes.

Forceps dark red-brown, penes slightly paler red-brown (see fig. 128). Tails white, unmarked; may be faintly brownish at extreme base.

Nymph reddish brown. Legs not banded. Gills cover most of the dorsum of the abdomen; these are pale greyish white with purplish tracheation. Dorsum of abdomen darker along the median line and along a line parallel to the lateral margin, inside the line of the gills. Ventrally, two lateral dark brown longitudinal stripes extend the length of the abdomen, near the lateral margin. Tails brown, tips white; not banded.