Mayfly Species Baetis flavistriga (BWOs)

Abdominal tergites 2-6 of male imago hyaline, tinged with yellowish brown; genitalia of the Baetis intercalaris type, the tubercle on the inner apical margin of the first forceps joint well developed.

Turbinate eyes small, oval, light brown with a yellowish tinge; stalk long, purplish brown, the upper third yellow. Face black; pale green markings around base of antennae and ocelli; antennae blackish. Thorax dark olivaceous; yellowish shading on the pronotum; an oblique yellow streak runs forward from the wing roots along the lateral margin of the mesonotum. Pleural sutures with yellow markings. Legs dirty whitish, femora pale yellow. Wings hyaline; venation pale. Intercalaries of the fore wing shorter than in B. intercalaris, particularly those of the first pair. Hind wing as in B. nanus (now a synonym of Baetis flavistriga).

Abdominal tergites 2-6 hyaline, tinged with pale yellowish brown; 7-10 light umber brown. The contrast between the basal and apical tergites is less marked than in Baetis phoebus and B. intercalaris. Sternites paler, the apical ones opaque. Slight black markings on the spiracular area. The tubercle on the first forceps joint well developed. This species has been separated from the closely allied B. nanus by the color of the eyes in living insects, the darker thorax, and the browner basal abdominal tergites.

Described as B. levitans

Body length 4 mm, wing length 4.5 mm

Abdominal tergites 2-6 of male imago pale yellowish white, with faint posterior and lateral brown shading; genitalia of the Baetis intercalaris type, the tubercle on the inner apical margin of the first joint scarcely or not at all developed (see fig. 164).

Turbinate eyes moderate in size; deep ruddy brown in color. Face and antennae black-brown. Thorax deep olive brown; lateral margins of the mesonotum, before the wing roots, often yellowish; scutellum dark, but a central and two lateral yellowish patches just anterior to it. Anterior projection of the metanotum whitish. Ruddy shading on the pleura, the sutures yellowish in part. Legs pale yellow. Femora more or less shaded with brown, which is continuous over the entire length of the fore femur, reduced to a median and an apical spot on the middle femur, and on the hind one to an apical spot only. Wings hyaline, venation pale. First and second pairs of intercalaries of the fore wing rather short, frequently broken; the next two pairs longer. Hind wing more than two and one-half times as long as its width; narrower than in B. cingulatus (now a synonym of Baetis phoebus), and more or less even in width throughout. Third vein well developed, running close to the hind margin. One intercalary may be present between the 2nd and 3rd vein.

Abdominal segments 2-6 pale whitish yellow, semi-translucent, the tergites shaded laterally and posteriorly with pale brown. Tergites 7-10 light russet brown; sternites opaque, creamy, with faint tinges of brown. Tracheae along the spiracular area strongly black, forming a wavy double black line with dorsal and ventral branches extending from it. This species has larger eyes than B. flavistriga, which has quite similar abdominal markings. The lack of the tubercle on the first forceps joint, the smaller eyes and darker scutellum, separate it from B. cingulatus.

Described as B. nanus

Body length 3 mm, wing length 4 mm

Abdominal tergites 2-6 of male imago yellowish, semi-hyaline; genitalia of the Baetis intercalaris group, the tubercle on the inner apical margin of the first forceps joint well developed.

Turbinate eyes small, oval (smaller than in B. flavistriga); pale yellowish brown in living specimens, bright red with yellow around the rims, in dried ones. Thorax pale olivaceous; the posterior portions may be tinged with smoky; anterior sutures shaded with brownish. Legs dull hyaline whitish, except the fore femora, which are yellow. Wings hyaline, venation pale. Third vein of hind wing well developed, extending to or beyond the middle of the hind margin. Between veins 2 and 3, traces of an intercalary are often present.

Abdominal tergites 2-6 semi-hyaline, yellowish, sometimes tinged faintly with brown; 7-10 opaque, Isabella brown in color. Sternites pale dull ochreous, the lateral areas noticeably hyaline. Tracheae and spiracular line with streaks and dots of blackish. Genitalia of the intercalaris type. Tails whitish.