Mayfly Species Caenis latipennis (Angler's Curses)

A species with long forceps; mesonotum dark brown, head paler posteriorly.

A purplish or blackish band across the head between the eyes; head paler before the posterior margin. Pronotum pale yellowish, with blackish shading in the median area. Mesonotum shining brown, darker than in C. forcipata (now a synonym of Caenis latipennis); pleura paler brown. Legs pale; darker markings at the apices of the femora. Fore tibia plainly more than twice the length of the femur. Wings semi-hyaline whitish, the subcosta and radius very dark and prominent. Abdominal tergites suffused heavily with blackish or blackish brown, much as in C. forcipata, but the dark color extends over the posterior tergites more than in that species. Sternites paler. Tails pale, “faintly annulate with brown” (Banks). Forceps long and sharp-pointed, but shorter relatively than in forcipata (see Pl. XXXIX).

This species, allied in type of forceps to C. forcipata, may be distinguished from it by the darker brown of the mesonotum, the more extensive dark shading of the abdominal tergites, and the relatively shorter forceps.

Described as C. delicata

Body length 4.5 mm, wing length 4 mm

A species with moderately long forceps; mesonotum reddish brown; head flesh colored with purplish markings.

Head of male flesh-colored, more or less shaded with purplish, usually leaving a paler area next to the posterior margin; a black line margins the vertex in front, and the posterior border; a wide purplish band extends across between the eyes. Eyes black; ocelli whitish, black-ringed at base; antennae pale, a purplish longitudinal streak on the outer side of the basal joint. Pronotum pale; anterior and lateral margins strongly, and posterior margin more faintly, bordered with blackish; median area more or less suffused with purplish; two black dots near the posterior margin, one on each side of the median line; antero-lateral corner and extreme lateral margin purplish black. Mesonotum reddish brown; a streak on each side of median line darker; faint dark markings bordering the scutellum; a faint dark V-mark anterior to it; a dark streak inward from the wing root, another anterior to wing. Metanotum reddish-brown, postero-lateral corners yellowish; considerable blackish shading in the anterolateral area; lateral and posterior margins black. Pleura similar in color to mesonotum; deeper brown above episternum; anterior margin blackish; extensive black markings above the bases of the legs and below the wing roots. Prosternum pale, with lavender markings; remainder of sternum pale in median area, brownish laterally.

Fore legs rather widely separated. A black antero-dorsal dot on fore coxa; fore femur purplish black on outer side, paler near middle, a black streak on the dorsal edge; tibia and tarsus whitish, faintly tinged with smoky. Middle and hind legs whitish; a black streak on coxa and trochanter; femur marked apically with a black triangle, its base toward apex of joint. Femora rather thickly speckled, especially in basal half and on dorsal edge, with small purplish black dots, which often tend to form a dark longitudinal streak in the middle of the outer surface. Dorsal edge of tibia with three or more black dots or short streaks. Wings hyaline whitish; subcosta and radius purplish; several longitudinal veins behind these are faintly lavender basally.

Abdomen yellowish white; apical tergites yellowish. Tergites 1-6 and anterolateral portion of 7, shaded with greyish lavender or purplish, deepest in color laterally; median area of tergites 1 and 2 usually pale, often cut by a dark median line; lateral margins pale. Posterior margins narrowly purplish black, paler in the median area; faint stigmatic streaks on tergites 1-6; heavy markings on 7 and 8, somewhat fainter on 9. Tergites 8-10 pale except for purplish lateral markings, forming with the lateral dark streaks an ovoid dark area around the stigma. A median and two lateral dark dots on 9; 3 longitudinal median streaks and two lateral dark dots on 10. Sternum with a pair of dark dots, obliquely arranged, very evident on each side of sternites 6-8; one or two dark dots on each side of the anterior sternites; a black transverse dash on each side of the anterior margin of 9. Forceps faintly smoky, tails whitish. Forceps of moderate length; stout at base, the apical two-thirds slender; tip sharp-pointed; slightly curved.

This species is allied to C. jocosa in the type of the genitalia, but differs in its much larger size, and in the presence of dots on femur and tibia. In the latter respect it differs from all other described species of our fauna except Caenis punctata, from which it is separable by reason of the longer forceps and lack of a dark femoral band, which is reduced to a dark triangle.

Described as C. forcipata

Body length 4 mm, wing length 4 mm

A species with long slender forceps; mesonotum light brown. A purplish or blackish band across the head between the eyes; head paler before the posterior margin. Eyes black, antennae pale. Pronotum pale yellowish, the median area with blackish shading; traces of a narrow black border line, most evident on the lateral margins. Mesonotum dark yellowish brown; scutellum paler, shaded slightly with black; a dark streak anterior to the wing root. Pleura similar to mesonotum, but with paler areas anterior to and below the wing roots; around the bases of the legs are some dark streaks. Sternum pale, faintly tinged with brown. Fore legs smoky at base; coxae and femora shaded with smoky, the femora with a black apical spot dorsally; tibiae and tarsi pale, faintly tinged with smoky. Middle and hind legs pale yellowish, a black streak on the outer side of each coxa and a black dot on the postero-ventral edge; a black streak on the outer side of the trochanter; a dorso-apical triangular mark on each femur, the apex pointing forward. Wings semi-hyaline whitish, the subcosta and radius dark, as usual.

Abdominal tergites 1-6 pale yellowish, heavily suffused with blackish; pale only in small lateral areas around the black stigmatic dots, and on the median area of 1 and 2, which show traces of a dotted black mid-dorsal line. Tergite 7 shaded anteriorly with black in the submedian areas; tergites 8-10 pale yellowish. Stigmatic dots present on tergites 1-7, very heavy on 7, obsolescent on 8-10; tergite 10 with three black streaks dorsally. Sternites pale yellowish; only faint traces of the obliquely-arranged dark dots on 6 to 8. Forceps and tails pale. Forceps very long and slender (see PL XXXIX).

This species is larger than C. jocosa (now a synonym of Caenis latipennis), and has a darker mesonotum, as well as longer forceps; it is distinguishable from C. latipennis by the longer, thinner forceps, which are not curved as in C. simulans (now a synonym of Caenis amica).

Described as C. jocosa

Body length 3 mm, wing length 3 mm

A small species, forceps moderately long; mesonotum light yellowish brown.

Head pale yellowish; a pale purplish tinge between the eyes, but paler again on the posterior margin; eyes black, antennae pale. Pronotum pale yellowish; on each side of the median line, on the posterior margin, is a blackish dot; area between and anterior to these dots faintly ruddy-tinged; slight black streaks on the lateral margin. Mesonotum light yellowish brown; scutellum paler, tinged faintly with smoky; anterior to the scutellum is a faint smoky median V; a dark lateral streak anterior to the wing root. A transverse blackish shade on the median area of the metanotum. Pleura pale yellowish, shaded lightly with yellow-brown, most intense in the region of the episternum. Sternum pale yellowish. Fore legs tinged with blackish basally; femora smoky, with a black streak apically on the dorsal side; tibiae rather more than twice the length of the femora, pale smoky; tarsi pale. Femora of the middle and hind legs pale yellowish; black dot on coxa, a faint black streak on trochanter; femur with a strong black dorso-apical streak, below which on the outer side is a small black dot. Wings semi-hyaline whitish; subcosta and radius purplish black.

Abdomen pale yellowish. Dorsal areas of tergites 1-6 with blackish suffusions, leaving as pale areas a lateral margin cut by a dark line along the posterior margin of each. Segments 1, 2, 5 and 6 with faint black stigmatic dots. Tergite 7 pale except for two submedian dark patches, and a large, well-defined stigmatic dot. Tergites 8-10 pale, 8 with faint black shading laterally; a faint dark median dot on 9; two blackish median longitudinal streaks, rather slight, on 10. Sternites pale yellowish; 1-5 with faint transverse black streaks laterally; 6-8 with two very faint obliquely-arranged dark dots on each side, the anterior dot near the lateral margin, the posterior one halfway between the median line and the lateral margin. Forceps pale, tails whitish. Forceps moderately long, sharp-pointed (see Pl. XXXIX).

The extent of black suffusion and markings varies considerably in different specimens; in pale specimens, the head may be almost wholly pale, the prothorax pale except for the two dark dots, the abdominal tergites with the dark shading very faint or almost wanting, except the stigmatic dot on 7. The somewhat darker thorax, longer fore legs and much longer forceps distinguish this species from Caenis hilaris: the smaller size and shorter forceps, as well as the paler thorax, separate it from forcipata (now a synonym of Caenis latipennis) and latipennis.

The females are larger than the males, bodies 6 to 7 mm. in length; tergites 1-6 largely suffused with purplish, the posterior margins pale; dark dots on middle and hind femora more numerous and more widely scattered than in the male.