Mayfly Species Eurylophella temporalis (Chocolate Duns)

A member of the bicolor group (now a synonym of Eurylophella bicolor), allied to both E. prudentalis (now a synonym of Eurylophella prudentalis) and E. doris (now a synonym of Eurylophella doris). No minute black dots on legs and abdomen, as in E. lutulenta (now a synonym of Eurylophella lutulenta).

Eyes reddish yellow. Head deep yellowish. Thorax bright brown, tinged with olivaceous dorsally. A paler orange-yellow streak anterior to the wing roots; pale creamy shading on the pleura at the wing bases. Legs yellow, shading into dirty white on the tibiae. Claws and joints of the tibiae blackish; a dark dot apically on the femora. Wings hyaline; venation hyaline. On the fore wing, the costa is slightly yellowish at the base. Abdominal tergites 2-7 deep brown, 8 and 9 reddish brown, 10 yellowish brown. Posterior margins of tergites 2-4 blackish. On the basal tergites the faint brown mid-dorsal line is partially geminate. A small subdorsal dark dot on the anterior margin of each tergite. Faint dark markings in the region of the spiracles; lateral margins of 8 and 9 narrowly yellowish. Pale yellowish white ventrally; basal sternites tinged with brown. The usual curved row of dark dots is distinct, and the ganglionic areas of sternites 4-7 are brown. Tails whitish, joinings dark brown.

The occipital tubercles of nymphs of both sexes are very strongly developed and distinctly conical in shape. The rows of dorsal spines are subparallel, sometimes slightly divergent on tergite 4. These spines on tergites 1-3 are long and tapering, finger-like and bent backward. The postero-lateral spines on segments 2 and 3 are well developed, that on segment 3 being almost twice as long as its width at the base. The general color is very dark brown, with a heavy sprinkling of minute pale dots. A pale dorsal stripe is present in some specimens. The operculum is sprinkled with pale dots, and may have two pale patches along the joint. Ventrally the curved row of dark dots and the dark lateral dashes are distinct. Tails distinctly banded, alternately dark brown and pale yellow.