Mayfly Species Ironodes nitidus (Slate Maroon Drakes)

A large yellowish brown species, slightly paler than the allied Ironodes californicus.

Frontal margin of head yellowish brown, reddish brown elsewhere; a distinct reddish spot on vertex between eyes, sometimes with reddish shading also around bases of antennae and ocelli. Thorax light yellowish brown. Pronotum extensively shaded with smoky brown. Mesonotum not much darker than pleura; depressions on each side of scutellum dark brown. Many specimens have a creamy area anterior to base of fore wing, containing two red streaks; creamy streaks may be present also on pleura, below wing roots. Reddish areas on pleura above base of fore wing, above base of fore coxa, and anterior to bases of middle and hind coxae. Reddish shading on coxae. Fore femur and tibia brownish amber to light brown; tarsus “whitish ochre’” (Eaton); apex of tibia, distal tarsal joint, claw and tarsal joinings darker brown. Middle and hind legs pale yellowish; tibiae and tarsi tinged with olive brown. Bases of tibiae, tarsal joinings, distal tarsal joints and claws dark brown. Wings hyaline, iridescent; stigmatic area of fore wing “tinted with extremely light raw-umber; the remainder of the marginal and submarginal areas more faintly so tinted, and the other part of the wing imperceptibly so" (Eaton). Venation red-brown, quite distinct. 8-9 basal costal cross veins; about 4 veins between bulla and stigma; 12-14 stigmatic veins, mostly simple, distinctly aslant.

Abdominal segments 2-7 semi-hyaline, yellowish brown with distinct olive tinge; posterior margins opaque, darker, this opaque area filling the postero-lateral angles; on dorsal portion of each tergite, this margin is almost black. Anterior margins of sternites very narrowly whitish hyaline, most evident in antero-lateral angles. Segments 8-10 opaque; tergites yellowish white with faint red-brown tinge, or “light brown ochre, sometimes with the dorsal joinings light brown” (Eaton). Genitalia smoky brown; penes as in fig. 108. Second joint of forceps not quite as strongly bowed near apex as in Ironodes lepidus, and much less bowed than in the allied I. californicus. Tails very pale yellow-brown beyond middle, slightly darker shade of same color basally.

Nymphs from Summerland, B. C., lent us for study by Dr. McDunnough, are very similar to those from California which we are tentatively calling Ironodes californicus. The Summerland nymphs are slightly darker red-brown dorsally, tracheae of gills less distinct; abdominal sternites with lateral dark streaks.