Mayfly Species Choroterpes terratoma

This is a blackish species with greyish abdomen. Head black above and in front, including basal segments of antennae; flagellum of antennae grey.

Thorax dull black, paler in the sutures, narrowly so in the notal furrow. Legs black and yellow, more black than yellow, except on tibiae of middle and hind legs, the usual middle and apical bands on the femora tending to run together. Wings subhyaline with the longitudinal veins dark brown except at the anal angle, where they are transparent, as are all cross veins.

Abdomen dark greyish-brown above, paler beneath. Dorsum with a narrow median pale line that is overlaid and widened by a series of inverted V-marks on the pale joinings of the middle segments. Side margins of segments 2 to 8 with a series of black marks shaped like fish hooks, pointed to rearward. Tails greyish brown, the joinings of the segments toward the base ringed with darker brown. Genitalia as in fig. 140.

The female is similar in coloration, only a little paler, with some yellow markings on the head (on median and occipital lines and around the eyes), and on the sides of the prothorax. The triangular prolongation of the 9th sternite projects far beyond the tip of the 10th segment and is notched at the tip.