Mayfly Species Epeorus deceptivus

A light brown species, very similar in general appearance to Cinygmula ramaleyi; genitalia distinctive.

Head and thorax reddish brown; lateral areas on each side of scutella of mesothorax and metathorax blackish brown. Legs light red-brown; apex of fore tibia, and all tarsal joinings, blackish brown; no markings on femora. Fore leg of male much longer than body; tibia slightly more than 1 1/2 times as long as femur; first, second and third tarsal joints subequal one to another. Wings hyaline; venation dark brown, veins rather fine. Cross veins in costal space, except the 12 to 14 in the stigmatic area, very indistinct.

Abdominal segments 2-7 semi-hyaline; 8-10 opaque. Anterior portions of tergites pale brown; posterior portions shaded with purplish brown; the posterior margins and anteriorly-directed projections from them on each side, darker purplish brown. Sternites somewhat paler than tergites; small oval brown patches at ganglionic areas. Tails brown. Genitalia pale brown; in structure, unlike any other species of this genus. Penes appear to vary somewhat in shape according to their functional condition. As shown in the original figure, and in one slide lent us by Dr. McDunnough, penes are somewhat widened subapically, the lateral lobes very prominent. In other slides and specimens which Dr. McDunnough has permitted us to examine, the penes are long, slender, somewhat finger-like; the lateral lobes, folded flat, are barely noticeable. Median spines long, slender, slightly incurved. Apical margin of forceps base convex, projecting forward between forceps limbs; often very slightly emarginate at median line. We present figures of penes to show the two different phases indicated (see fig. 105, two views).