Mayfly Species Procloeon bellum (Tiny Sulphur Duns)

Abdominal tergites 2-6 of male imago pale yellowish, the posterior margins narrowly ruddy brown.

Head and antennae dull blackish. Turbinate eyes deep reddish in dried specimen. Deep olive brown shading on the prothorax; mesonotum olivaceous shaded with variable amounts of yellowish sub-dorsally; lateral and posterior margins tinged with ruddy. Metanotum darker, deep olive brown; sutures darker; anterior dorsal portion shaded with ruddy. Legs yellowish white. Wings hyaline. Hind wing moderately broad, two longitudinal veins. Abdominal tergites 2-6 pale yellowish, semi-hyaline; on the posterior margin of each is a narrow ruddy brown band extending to the spiracular area, where it ends in a faint small reddish patch. Sternites 2-6 likewise pale, but with no ruddy posterior markings. Tergites 7-10 bright ruddy brown; sternites opaque yellowish shaded laterally with reddish, and with faint traces of ruddy posterior margins. Spiracular line blackish. Forceps and tails white. See figure 166.

Distinguished from C. ozburni (now a synonym of Procloeon ozburni) by the paler thorax and the ruddier color of the posterior tergites. Hind wing relatively wider and posterior margins of tergites narrower than in the related C. intermediale (now a synonym of Procloeon intermediale). Closely allied also to C. caliginosum (now a synonym of Procloeon caliginosum), but with more ruddy abdominal markings than in that species.

The nymph has double gills on the basal segments at least; abdomen marked dorsally with brown, segments 4, 5, 7, 8 and 10 being paler; tails dark distally, with pale band about 1/3 from the tip.