BITING MIDGES — WIRTH AND BLANTON 265 



Fore and mid femora pale brown on basal portions, hind femur with a 

 broad median darker brown band; wing 1.11 mm. long. 



nigrigenus Wirth and Blanton (p. 308) 



22 (1). Pale spots at periphery of wing very faint 23 



Pale spots at periphery of wing well defined; macrotrichia of wing more 

 or less abundant 25 



23. Wing practically bare of macrotrichia; stigmal spot blackish; mesono- 



tum blackish 24 



Wing with sparse but widely distributed macrotrichia; stigmal spot 

 scarcely darker than rest of wing; mesonotum pale brown with faint 

 pattern of punctiform brown dots . . alahialinus Barbosa (p. 398) 



24. Small species, wing 0.65 mm. long; second radial cell short, costa 



ending at 0.53 of distance to wing tip; halter yellowish; legs yellow 

 except for dark knee spots; mesonotum with bluish pruinosity and a 

 sublateral pair of narrow blackish bands. 



pusillus Lutz (part) (p. 292) 



Large species, wing 0.90 mm. long; second radial cell long, costa ex- 

 tending to 0.64 of distance to wing tip; halter dark; legs dark, faint 

 pale bands at base of hind tibia; mesonotum uniformly dull, dark 



brown stigmalis Wirth (p. 467) 



25 (22). Wing with a pale spot straddling middle of vein M2, or veins Mi and 

 M2 entirely pale-margined, including this area 26 



Wing with no pale spot straddling vein M2, this vein usually dark to 

 apex 54 



26. Wing with pale markings extensive, interconnected 27 



Wing dark with well-separated pale spots 32 



27. Halter knob pale; mesonotum with prominent pattern of large patches 



or Hnes; anterior margin of wing with one very dark spot over second 

 radial cell ; cell R5 with two pale areas between end of costa and .ving 



tip 28 



Halter knob dark; mesonotum with a pattern of punctiform dots; 

 anterior margin of wing with three very dark spots, cell R5 with three 

 pale areas between end of costa and wing tip. 



arubae Fox and Hoffman (p. 464) 



28. Cell Mi with distal spot not or very narrowly reaching wing margin . 29 

 Cell Ml with distal pale spot broadly reaching wing margin; mesonotum 



yellowish with dark brown sublateral bands 30 



29. Cell Ml with distal pale spot shorter than dark area between it and wing 



margin; cell R5 with poststigmatic pale spot not enclosing a dark 

 spot behind second radial cell; mesonotum yellowish with dark brown 



sublateral bands pifanoi Ortiz (p. 384) 



Cell Ml with distal pale spot longer than dark area between it and wing 

 margin; poststigmatic pale spot in cell R5 U-shaped, enclosing a 

 small dark spot behind second radial cell; mesonotum grayish pruinose 

 with three narrow dark longitudinal lines. 



paucienfuscatus Barbosa (p. 381) 

 30 (28). Hind femur and tibia dark on apices. 



galindoi Wirth and Blanton (part) (p. 349) 



Hind femur with subapical pale ring; hind tibia with apex broadly 



pale 31 



