Mayfly Species Ameletus lineatus (Brown Duns)

A large pale species, clear-winged, and without ganglionic markings on the venter of the abdomen. Known only from females and nymphs.

Head yellowish brown. Prothorax dark yellowish brown, narrowly purplish on the posterior margin. Mesonotum clear greenish yellow, scutellum with blackish lateral margins. Pleura and sternum brown, the sternum dark brown on the posterior portions of the prothorax and mesothorax. Legs brown. Wing with no clouds along the cross veins.

Abdominal tergites flesh-colored, margined laterally and posteriorly with orange-brown. Margin of pleural fold pale. Indistinct dark submedian streaks present. Sternites 1-6, and anterior half of sternite 7, flesh-colored; sternites 8-10, and the posterior half of 7, light olive brown. A purplish median mark on sternite 6, but no definite ganglionic marks on the other sternites. Submedian oval depressions present. Antero-lateral angles of sternite 8 whitish. Tails purplish brown, joinings darker.

The nymph has a cream-yellow thorax and abdomen, mottled and marked with dark brown. Legs banded. Tergites 6 and 7 largely cream colored; tergites 8-10 largely dark brown. Ventrally, three continuous dark brown stripes extend the length of the abdomen; one is median, the others lateral in position. Each dark lateral streak is separated from the lateral margin by a pale line. Lateral margins of segments 6-9 are narrowly flattened and thin; postero-lateral spines present on segments 2-9, well developed on 5-9. Tails whitish, with the two usual dark bands.

The larger size and the apparent lack of dark ganglionic markings seem to distinguish this from the other two eastern species, A. ludens and A. browns.