Mayfly Species Caudatella jacobi

Head deep brown; eyes (dried) blackish with slight reddish tinge. Pronotum deep brown, the lateral edges pale yellowish; mesonotum deep brown, shaded with paler laterally and posteriorly, latero-anterior edge deep blackish; scutellum long, narrow, with palish area at base and the thin ends of the axillary cords projecting caudad beyond its apex for a considerable length (as in tibialis and hystrix). Pleura and sternum blackish, shaded with paler around bases of legs and with a large pale yellowish area cephalad of wing-base, crossed by a black line. Metathorax and abdomen blackish, the posterior edges of abdomen paler brown, giving a slight ringed appearance. Forelegs with femora and tibiae pale smoky, the tibia long and almost twice the length of femur; tarsi dull ochreous, paler than the preceding joints. Midand hindlegs dull ochreous, the femora considerably shaded with smoky. Wings narrow, hyaline, with entirely pale and inconspicuous crossveins; longitudinal veins fine and pale brownish in costal half of wing. Tails broken. Length of forewing 10 mm. (After McDunnough 1939.)

Head light brown, eyes blackish. Thorax clay brown, yellowish patch anterior to base of forewing, containing a black line that descends to the coxa of the foreleg; lateral sutures marked with black; wings hyaline, veins light brown; legs dull ochreous. Abdominal terga black with posterior light margins, posterior two segments pale with lateral dark areas; sterna black, posterior two segments with pale lateral margins (caudal filaments missing in described specimen).

Cerci 8-9 mm; terminal filament 10-11 mm. Head brown without occipital tubercles; antennae brown; maxillary palpi three-segmented. Pronotum and mesonotum brown without tubercles and with irregular light brown markings. Legs brown with rows of long hairs and a few short spines similar to those in fig. 15; tarsal claws with 6-8 denticles. Abdominal terga brown, terga 1-7 dark brown laterally, lighter medially, light areas increase in width posteriorly so that terga 8-10 are nearly light brown as in fig. 24; conspicuous, paired dorsal submedian tubercles on segments 2-9, as in fig. 24, tubercles are narrowly separated on tergum 2 and become more widely separated to tergum 7; tubercles are slightly closer together on terga 8 and 9; sterna dark brown with light brown lateral margins as in fig. 9, anterolateral corners may be darkened. Caudal filaments brown, lateral cerci are 75%-85% as long as terminal filament.