Mayfly Species Baetisca obesa (Armored Mayflies)

Abdominal tergites of male imago pale reddish brown; venation yellowish on costal margin, otherwise pale.

Head ferruginous; antenna similar in color, the filament generally pale. Thorax ferruginous; sternum "paler behind, especially the space between the posterior coxae" (Walsh). Legs pale greenish yellow; in the fore leg, the apex of the femur, tips and joinings of the tarsi, are slightly fuscous. Middle and hind legs paler, only the tips of tarsi cloudy. Wings hyaline; longitudinal veins of the costal margin yellowish, radius piceous at the extreme base, "a few of the principal veins slightly tinged with fuscous” (Walsh); all other veins pale. Cross veins almost invisible. Abdominal tergites pale reddish brown, the posterior margins whitish; sternites somewhat paler. Tails whitish, the joinings fuscous, especially in the basal portion. Forceps pale, sometimes reddish toward the tip. Genitalia as in fig. 148.

The nymph has both dorsal and lateral spines on the mesonotal shield; the genae are somewhat produced into spine-like processes; the frontal projections are very prominent and well developed. The paler venation separates this species from the allied Baetisca laurentina.