NO, I BLACK FLIES OF GUATEMALA — DALMAT 99 



Head : Dichoptic ; base of f ronto-ocular triangle equal to its height. 

 Antenna 700 [x long, 11 -segmented, well tapered; segment 3 less than 

 half of segments 1+2, 3<4-|-5, 3=11 ; scape and pedicel light brown, 

 the flagellum black. Palpi black. Frons dark brown, with gray prui- 

 nosity, a single row of black hairs on either side of midline, and with 

 several short, narrow, golden, scalelike hairs. Clypeus dark brown, 

 gray-pruinose, irregularly covered with long, fine black hairs and 

 shorter, appressed, golden scalelike hairs. Occipital region dark brown, 

 with long black hairs and with somewhat shorter golden yellow hairs. 

 Cornuae of buccopharyngeal apparatus heavily sclerotized along outer 

 margins, which are broad and blunt ; median space hyaline and smooth. 



Thorax : Mesonotum black ; prescutellar region gray-pruinose ; 

 from the middle of the prescutellar region, and from each of its an- 

 terior angles, there extends a narrow longitudinal stripe of gray prui- 

 nosity, these stripes converging at the middle of the anterior margin of 

 mesonotum; the stripes are most easily visible when the specimen 

 is placed with the head away from the light source, and the light hit- 

 ting the scutum almost directly (90-degree angle) ; long, appressed, 

 golden, scalelike hairs densely clothing entire mesonotum ; very few 

 long, fine, black hairs in prescutellar region. Humeral angles brown, 

 gray-pruinose, with golden scalelike hairs. Scutellum brown, some- 

 what lighter posteriorly, with appressed, golden, scalelike hairs and 

 long black hairs. Postnotum velvety dark brown, gray-pruinose, 

 devoid of hairs. Pleura brown, with gray pruinosity ; pre-alar cluster 

 composed of both golden and black hairs. Stem of halter light brown 

 at base, somewhat darker apically, the knob light brown. Wings, 4.3 

 mm. long and 1.8 mm. wide; relation of body length to wing, 1:1.1; 

 Sc usually completely pilose ; Ri completely pilose, with several rows 

 of hairs, the apical third also with spines ; R2+3 completely pilose ; CU2 

 arcuate ; discal cell present. 



Legs: Leg i, length, 3.5 mm.; entire leg dark brown except for 

 femur which is somewhat lighter. Leg 2, length, 3.4 mm. ; coxa dark 

 brown ; trochanter brown ; femur brown with very small dark-brown 

 apical ring ; tibia brown with dark-brown apical and basal rings ; basal 

 half of basitarsus brown, the apical half dark brown ; tarsal segments 

 2-5 dark brown. Leg 3, length, 4.4 mm. ; coxa, trochanter, femur, and 

 tibia as on leg 2 ; basitarsus brown ; tarsal segments 2-5 dark brown ; 

 relation of basitarsus to second segment, 4.5 : i ; calcipala well de- 

 veloped, broad, pedisulcus absent ; claw with basal heel developed into 

 long spur, and with secondary shield-shaped process emerging from 

 the base of the spur; inner face of claw with striations (pi. 35, 

 fig. 270). 



