Mayfly Species Attenella attenuata (Blue-Winged Olives)

A species considered to be of the simplex (now a synonym of Dannella simplex) group; fore tarsus of male comparatively short, third joint of forceps long, about one-half the length of the second.

Eyes deep brown. Head and thorax deep blackish brown. Legs pale yellowish white; fore legs darker, the tibia and tarsus largely smoky. The middle and hind femora may show an apical brownish spot. Fore tibia about one and one-half times the length of the femur, and about as long as the entire tarsus. Hind tibia twice as long as the tarsus. Wings hyaline; venation hyaline, cross veins faint except in the stigmatic area, where they are strongly anastomosed. Abdomen dark brown dorsally, the three posterior segments paler brown. Paler ventrally, the eighth sternite quite pale creamy brown. Forceps whitish, shaded at base with light brown; third joint very long, about one half the length of the second. Penes united except for a slight V-shaped apical cleft; widened apically, narrowed again at the extreme apex (see fig. 157). Tails white.

Nymph rather slender; abdomen somewhat flattened. Occipital and prothoracic tubercles present, also a single median anterior and a similar posterior mesothoracic tubercle. The lateral extensions of the abdominal segments are prolonged into shorter and blunter postero-lateral spines than in E. simplex (now a synonym of Dannella simplex); the lateral margin of segment 8 is distinctly and characteristically sinuate. Dorsal spines are present, most distinct on segments 4-7. Gills present on segments 4-7 only. General color light brown. A few blackish spots are present on the anterior portions of the pronota and mesonota, and one dark spot near the base of the wing pads. Legs slender, pale; each femur is marked with a narrow broken median dark band; tibia with a median black ring, and a broader black band at the base of the tarsus. 8 to 9 denticles on each claw. Pale submedian dorsal stripes may be present, also a median dark streak on the apical tergites; on the anterior margins of the first five tergites are lateral pale dots; the lateral extensions are pale, with a median brown band. Ventrally a lateral row of dark dashes is present on each side, a curved row of four small dark dots across each sternite, and sometimes dark median blotches on the anterior margin of each. Tails rather short, pale in immature nymphs, with a dark band before the apex; in mature nymphs the tails are reddish at the base, and may be crossed by two dark bands beyond the middle. Basally they bear short spines; apically each is fringed with long fine hairs.