Mayfly Species Cinygmula subaequalis (Small Gordon Quills)

Head reddish yellow; “a shining black ring at base of each ocellus, antennae pale” (Bks.). Thorax rather reddish yellow, posterior portion of notum darker. Legs pale, “a black dot at tip of femur and tibia I" (Bks.). Wings hyaline; venation mostly brown, no cross veins dark-margined; stigmatic area brownish yellow. “About five costals before bulla, fourteen beyond, a few near the middle are crossed” (Bks.). Hind wings not dark-margined. Basal joint of fore tarsus of male fully two-thirds as long as second; third equal to second; fourth “‘scarcely longer than first, the fifth not one-third of first.” (Bks.). Abdomen pale; “segments dark on apical one-third or one-half above, last three segments brownish” (Bks.) Forceps pale. Tails faintly dark.

Described as C. atlantica

Body length 7 mm, wing length 8 mm

A rather small pale species; wings not tinted; spines on lower outer margin of penes.

Head yellowish brown; dark brown between eyes. Thorax light brown; lateral areas of pronotum, and postero-lateral areas of mesonota and metanota, shaded with darker brown. Fore legs smoky brown. Middle and hind legs yellowish brown. Wings hyaline, not tinted; all veins fine, brown. Abdominal tergites 2-6 semi-hyaline, pale, with brown shading laterally. Tergites 2 and 3 pale in central median area only; tergites 4 to 6 largely pale, the brown shading restricted to postero-lateral areas. Submedian pale dashes, partially outlined in brown, are faintly indicated. Sternites pale ochreous, 2-6 semi-hyaline, 7-9 opaque. Tergites 7-10 opaque, almost wholly brown. Tails pale brown; penes smoky brown. A spine is present on lower outer margin of penes on each side, but none in inner margin (see fig. 103).

This species is allied to Cinygmula par, by the structure of the genitalia, but it lacks the inner spine on the penes found in that species. The paler abdominal tergites and lack of mid-ventral dark markings in C. atlantica serve to distinguish it from C. par.