Mayfly Species Stenacron carolina (Light Cahills)

A yellowish species, of interpunctatum (now a synonym of Stenacron interpunctatum) group; no dark marks on face; lateral dark mark on pronotum; no spiracular dots; abdominal segments dark on posterior margins; no spines on lower lateral portion of penes; eyes rather small and remote.

Head and thorax pale yellowish or reddish yellow; no distinct dark marks on head, but a reddish median line on vertex, and posterior margin reddish. Antennae dusky. Eyes relatively small, remote. A rather faint dark oblique streak on each side of pronotum. Femora yellowish, sometimes with greenish tinge; median and apical dark bands on fore and middle legs, apical dark mark on hind leg, sometimes a faint trace of dark median spot. Tibiae and tarsi yellowish, more or less tinged with smoky; apices of tibiae and tarsal joinings darker. Basal fore tarsal joint 1/2 or slightly more than 1/2 the length of second. Wings hyaline; longitudinal veins amber brown, cross veins rather darker brown. Costal cross veins before and in region of bulla with a dark spot at the costal margin, instead of being uniformly margined; radial cross veins before bulla and two or three at bulla dark-margined in usual manner, but not connected by a dark dash. Apical portion of costal margin yellowish brown. Outer margin of hind wing narrowly dark-bordered. Abdominal segments 1-7, sometimes basal portion of 8, more or less hyaline, with faint greyish or greenish tinge. Posterior margin of each segment, dorsally and ventrally, with a narrow but distinct dark border, so that abdomen appears annulate; these dark margins deeper in color on tergites, especially in dorsal area. No dark spiracular markings. Segments 8-10 opaque, tinged with reddish brown. Forceps brown; penes quite similar to those of S. frontale (now a synonym of Stenacron interpunctatum), being narrower and more rounded apically than in S. interpunctatum; differ from both of these in the lack of distinct short spines on lower lateral portion, only a slight roughening of the margin being evident (see fig. 91, carolina type (Now a synonym of Hexagenia limbata)). Tails rather deep smoky brown basally, somewhat paler brown apically; joinings opaque, appear very faintly darker. This species seems distinct from all others described in this genus, by reason of the lack of lateral spines on the penes together with the yellowish dark-banded abdomen.