Mayfly Species Rhithrogena brunneotincta

A species allied to Rhithrogena robusta; portions of both wings are distinctly tinted with brownish amber.

Head brown; paler shading in region of antennae. Thorax deep pitch-brown; mesonotum shaded with paler brown anterior to scutellum. A reddish shade anterior to wing roots; pleura and bases of legs shaded with ochreous brown. Fore legs deep smoky, femur with slight olive tinge. Middle and hind legs olive brown, femora and tarsi shaded slightly with smoky. Wings hyaline; basal two-thirds of fore wing and costal half of hind wing distinctly tinted with brownish amber. Veins and cross veins brown, fairly strong; cross veins in stigmatic area thickest, those in the costal space not much anastomosed, as is usual in other species of the genus.

Abdominal tergites deep brown; lateral margin and small antero-lateral and postero-lateral triangles lighter olive brown. Intersegmental areas on basal tergites narrowly pale, so that dorsum appears annulate. Sternites lighter olive brown, posterior ones distinctly brown. Forceps and tails deep smoky. (See fig. 102, after McDunnough).

This species is allied to the western R. robusta, from which it may be distinguished by the brown-tinted wings and structural details of the penes. In robusta, penes are sharply truncate at tip, the inner apical spine is not recurved, and lateral spines differ slightly from those of the eastern brunneotincta.