Mayfly Species Anafroptilum semirufum (Tiny Sulphur Duns)

Abdominal tergites 2-6 of male imago ruddy brown on the posterior half or three-quarters, the remaining areas pale hyaline; a prominent tubercle between the bases of the forceps limbs.

Turbinate eyes red brown, in dried specimen; appear as flat discs, not shriveled longitudinally. Head pale yellowish below the antennae; vertex brown, with ruddy tinges around the ocelli. Thorax olivaceous brown; lateral margins of mesonotum paler; scutellum white, tinged anteriorly with ruddy. Anterior margin of metanotum pale; central area with strong ruddy tinges. Pleura brown, with small pale areas at bases of legs. Mesosternum pale yellowish. Legs yellowish white; femora with a faint ruddy streak in the median area long the dorsal edge. Wings hyaline, venation pale. 3-4 cross veins in the stigmatic area of the fore wing; hind wing narrow, two longitudinal veins; costal projection strong.

Abdominal tergites 2-6 shaded heavily with ruddy brown on the posterior half or three-quarters; anterior half of tergites 2 and 3 pale hyaline; pale area on 4-6 narrower, and divided by a fine oblique shade of brown into a large dorsal patch and a smaller one on the antero-lateral margin. Tergites 7-10 opaque ruddy brown. Sternites whitish; 2-6 hyaline, 7-9 opaque with faint ruddy shading laterally. A faint broken black line along the spiracular area. Forceps and tails white. Between the bases of the forceps limbs is a prominent tubercle.

The prominent ruddy banding of the abdomen and the brighter color of the posterior tergites distinguish this species from the allied C. bifurcatum (now a synonym of Anafroptilum bifurcatum).