Mayfly Species Serratella frisoni

A member of the serrata group (now a synonym of Serratella serrata); male imago distinguished by the pale whitish anterior abdominal segments. Nymph unknown.

Head and thorax deep blackish brown. Mesothorax broad; axillary cords barely extending beyond the tip of the scutellum; pleura with lighter brown tinges. Fore femora light sepia brown; tibiae and tarsi dull whitish; tibiae slightly shaded at base with sepia, and rather long, being about equal in length to the entire tarsus and more than twice the length of the femur. Middle and hind legs whitish; femora tinged with brown; tibiae about as long as the femora. Wings hyaline, all veins pale; a brown tinge at the extreme base. Abdominal segments 1-6, and the anterior half of segment 7, dull whitish, semi-hyaline; segments 8-10, and the posterior half of 7, pinkish brown, opaque; paler ventrally. On the anterior segments traces of a fine ruddy dorsal line are evident; also “lateral rows of small ruddy spots or streaks situated one on each segment in the central area” (McDunnough). Forceps pale with tinge of brown. Between the forceps at the base is a prominent tubercle, as the bicolor (now a synonym of Eurylopella bicolor) group; however, there are small lateral barbs apically on the penes. Tails white, unmarked.