Mayfly Species Ephemerella alleni

Caudal filaments 12.7 mm. Head dark brown. Antennae with scape and pedicel dark brown; basal flagellar segments dark brown, distal segments pale. Ocelli white; base brown with proximal black ring. Compound eyes contiguous; upper portion orange-red; lower portion black. Thorax dark brown with variable pale and black markings; prothorax with median ridge. Wings hyaline with milky tinge; stigmatic area lightly clouded with white; costa and subcosta light brown; some longitudinal veins light brown distally, otherwise pale; intercalaries and crossveins hyaline. Forelegs brown to pale brown, each tarsal segment with pale distal ring; length (mm) of segments: trochanter = 0.4, femur =2.0, tibia=2.9, tarsus I =0.1, tarsus II = 1.0, tarsus Il = 1.1, tarsus IV = 1.0, tarsus V = 0.3. Midand hindlegs pale with brown distal tarsal segments and claws. Abdomen dark purple-brown anteriorly, red-brown posteriorly. Abdominal terga with pale anterior margin with paired, brown, submedian, saggital streaks, and with pair of pale sublateral spots ringed with brown. Abdominal pleura pale. Abdominal sterna pale, with brown triangles in anterolateral corners and paired submedial maculae; segments 1, 2, and 4-7 with ganglionic marks; sternum 9 brown laterally. Genitalia (fig. 1) brown with forceps pale medially. Penes with medioapical cleft and dorsal mediolongitudinal groove. Penes lobes with stout, spinulelike setae medially near outer margin, and with small, spinulelike setae along inner margin of cleft; with setal pits near outer margin in distal half, and with slightly developed apical projections. Forceps segment 2 slightly expanded distally; forceps segment 3 ovoid, with length nearly 1.5 X width. Median caudal filament and cerci subequal in length, purple-brown proximally, pale distally, with dark annulations at distal margin of each segment, and covered with hairlike setae.

Caudal filaments 12.1 mm. Head pink with dark brown triangle on occiput. Thorax with pink maculation; longitudinal wing veins brown. Abdominal segments 1-8 translucent; segments 1, 8—10 with extensive pink maculation; segments 6 and 7 with few pink maculations; terga 1-10 with posterior margins brown. Otherwise similar to male.