Mayfly Species Thraulodes speciosus

This is a beautiful fawn-colored species with long ringed tails, and cross veins of the fore wings heavily marked with brown. Head blackish with the very large and attingent upper eyes fawn-colored, and flagella of antennae pale. Thorax fawn-colored with blackish lines in the pleural sutures, and especially around the leg bases. Legs honey yellow, with the fore femur heavily streaked with blackish, the other femora with heavy brown apical cross-bands; both ends of fore tibiae and the tips of all tarsi touched with brown. Wings hyaline with pale brown longitudinal veins and dark brown cross veins over most of their area. The costal cross veins are much heavier before the bulla than in the stigmatic area. Little brown spots surround the breaks of the bulla. Two rather well defined lines of more heavily marked cross veins traverse the basal half of the wing; one from the bulla backward through the posterior branch of the radial sector, to the median vein; the other parallel to it and nearer the wing base. In the hind wing the costal angulation is prominent, rounded on end, and about midway the wing length. Only two or three cross veins just behind the outer end of the hump are heavily marked with brown.

Abdomen brown at base and rufous at tip with intervening segments 3 to 6 pale and strongly marked with apical cross bands of brown. Through the translucent venter the nerve ganglia show plainly. The last ganglion is heavily pigmented with black. Tails white, heavily ringed with blackish on the joinings of the segments. Forceps hyaline, three-jointed beyond a bulbous segment-like basal enlargement that is covered by the 9th sternite, the Iast segment half as large as the one before it, both very small. Penes honey yellow, separated by a V-shaped cleft, each constricted in the middle then dilated to a broad doubly rounded apex with a long straight stout spine arising at the end. See fig. 146.