Mayfly Species Siphloplecton speciosum (Pseudo-Gray Drakes)

A rather aberrant member of the genus; distinguished by the pale wings, and the very short second member of each pair of cubital intercalaries.

Frons pale. Remainder of head, and thorax, dark red-brown. On the thoracic sternum, a pale transverse band between the middle and hind pairs of coxae. Femora reddish brown, with dark reddish bands near the apex, less distinct on the fore legs; median area, and apices of middle and hind femora, pale. Fore tibia pale reddish brown, paler apically; tarsi pale, joinings narrowly darker. Middle and hind tibiae pale shaded medially with purplish red. Wings pale, hyaline; humeral cross vein dark purplish brown. All other cross veins wholly pale, except those of the basal costal space, which are pale brown next to the subcosta. Main longitudinal veins of the fore wing purplish brown at the extreme base, pale yellowish brown beyond; some almost colorless. No trace of the usual basal and bullar clouds. In the cubital space of the fore wing, each of the two pairs of intercalary veins consists of a moderately long anterior vein followed by a very short faint posterior one. Costal angulation of the hind wing tends to be acute.

Abdominal segment 1, and tergites 2, the apical half of 7, and 8-10, dark reddish brown; lateral areas of 7-10 pale. Tergites 3-6, and basal half of 7, largely pale, partially semi-hyaline; brown markings less extensive than in Siphloplecton basale. Lateral and posterior brown margins rather wide on tergite 3; narrower and less strongly indicated on 4-6. An incomplete dark median line on each; on each side of this, a short dark streak, and another nearer the anterior margin, toward the pleural fold. Black pencilings on tergite 6 only. Sternites 2-9 wholly pale, except for brown oval patches on each side of the median line on sternite 2; greyish ganglionic areas on the three apical sternites; brown lateral shading on sternite 9. Tails white; joinings purplish black. Genitalia largely pale (see fig. 115).

Gills double on segments 1-3 of the nymph; claws of the second and third leg relatively shorter than in S. basale; venter of abdomen marked with a brown median longitudinal streak, and on each side near the pleural fold a row of black dots, two on each side of each sternite.