Mayfly Species Ameletus browni (Brown Duns)

A small clear-winged species; wings with a faint amber tinge, especially in the basal costal area.

Head and thorax deep mahogany brown. Median line of mesonotum broadly light yellowish brown; some oblique pale areas extend forward and downward from the wing roots and around the bases of the legs. Legs yellowish; femora tinged with ruddy brown; fore femur considerably darker than the others. Wings hyaline; a very faint amber tinge, most evident in the basal costal area; veins and cross veins fine, brown; cross veins in basal costal space indistinct. Abdominal tergites rather deep yellow; posterior margin of each tergite narrowly brown, and poorly defined brownish triangles extending forward from the end of each dark band above the pleural fold, their apices almost reaching the anterior margin. Sternites slightly paler yellow, shaded faintly with ruddy brown along the lateral margin; sternites 1-7 each with an oval brown ganglionic spot. Forceps and tails faintly smoky; tails with narrow dark joinings. Penes as in fig. 118.

Nymph light sepia brown, the head and thorax with pale streaks and lunate markings. Abdominal tergites marked with a wide pale median band, white submedian and antero-lateral dots and lateral oblique streaks; sternites pale brown, with traces of a whitish mid-ventral line, submedian dark streaks and a dark dot in the antero-lateral angle of each. Legs pale, with brownish black bands; gills rather small, oval, whitish, the edge darker, tracheation not visible. Tails blackish in the basal three-fourths, white beyond this, with a narrow dark tip. This species, allied to A. dissitus and A. cooki, is distinguished from each of these by the finer details of the penes structure.