NO. I BLACK FLIES OF GUATEMALA — DALMAT II7 



Simuliiim (Eusimulium) donovani Vargas, Rev. Inst. Salubr. Enferm. Trop., 



vol. 4, No. 4, pp. 359-360, figs. 34-36, 1943 (female). 

 Simulium diazi De Leon, Bol. Sanit. Guatemala, vol. 52, p. 70, fig. 7, 1944 (pupal 



respiratory filaments). 



Male (pi. 22, figs. 19-21). — 3.5 mm, long. 



Head: Holoptic. Eyes very dark reddish brown above, black be- 

 neath. Antenna 500 jx long, 11 -segmented, slightly tapering, the last 

 segment pointed ; segment 3 = 4-1-5, 3=1-1-2, 3>ii; completely black. 

 Palpi dark brown at base, black apically. Clypeus black, yellowish- 

 white-pruinose, with pale-yellow hairs. 



Thorax : Velvety black, with white pruinosity covering entire 

 mesonotum, dependent on position of light source; densely covered 

 with long, narrow, brassy-yellow, scalelike hairs along the periphery ; 

 few such hairs on disc; long, yellow, erect hairs in the prescutellar 

 region ; along the anterior margin some of these hairs appear silvery. 

 Humeral angles dark brown, with silvery pruinosity and short, yellow, 

 scalelike hairs. Scutellum black, with very long yellow hairs and 

 several appressed, yellow, scalelike hairs. Postnotum black, with 

 silvery pruinosity that appears to be in W-shaped pattern, devoid of 

 hairs. Pleura dark brown, gray-pruinose, all tufts pale yellow; pre- 

 alar group composed of brassy-yellow hairs. Stem of halter dark 

 brown, the knob tan to rose. Wings, 3.5 mm. long and 1.2 mm. wide; 

 relation of body length to wing, i : i ; Sc pilose along basal fifth ; Ri 

 completely pilose, with spines also on distal half ; R2+3 pilose except 

 for small basal region ; Cua arcuate ; discal cell absent. 



Legs: Leg i, length, 2.7 mm.; coxa dark brown; trochanter dark 

 brown, its base somewhat lighter ; femur light brown, the apex dark ; 

 basal and apical thirds of tibia dark brown, the middle light ; tarsus 

 black ; tarsal segments 1-3 each with lance-shaped spur extending from 

 its apex. Leg 2, length, 2.4 mm. ; coxa and trochanter dark brown, 

 femur and tibia as on leg i ; basitarsus brown on basal third, black on 

 apical two-thirds ; tarsal joints 2-5 black ; basitarsus and second seg- 

 ment with apical spur. Leg 3, length, 2.8 mm. ; coxa and trochanter 

 dark brown ; femur and tibia as on leg i and 2 ; basal three-fourths of 

 basitarsus and basal third of second segment light brown, the re- 

 mainder of these segments, as well as all of segments 3-5, dark brown 

 to black ; second joint with apical spur ; relation of basitarsus to second 

 segment, 4.5 : i ; calcipala well developed, not quite reaching the pedi- 

 sulcus ; pedisulcus formed one-third the distance from the base of 

 second segment, hot very deep ; some very long hairs on tibia and 

 basitarsus. On all legs, the light areas are clothed with silver to 

 yellow hairs and the dark areas wath black hairs. 



