NO. I BLACK FLIES OF GUATEMALA DALMAT 69 



Mesonotum with only black hairs ; only basal third of Sc pilose. 



agidrrei Dalmat 

 2. Sc pilose along its entire length; length of hind basitarsus 3.1-3.4 times its 



width pacheco-lunai (De Leon) 



Sc pilose along its basal three-fourths ; length of hind basitarsus never more 

 than 2.8 times its width roblesi ( De Leon) 



SPECIES OF THE GENUS GIGANTODAX, BASED ON EXTERNAL 

 CHARACTERS OF THE MALES 



Hind leg with calcipala evenly rounded ; the basal heel of claw produced to form 

 a rather blunt, short spur ; mesonotum orange to brown ; relation of basitarsus 

 to second tarsal segment 7.2 : i ivrighti Vargas, Martinez, and Diaz 



Hind leg with calcipala more angular, the basal heel of claw produced to form a 

 sharp, well-developed spur ; mesonotum reddish brown ; relation of basitarsus 

 to second tarsal segment 8:1 aquamarensis (De Leon) 



SUBGENERA OF THE GENUS SIMULIUM, BASED ON EXTERNAL 

 CHARACTERS OF THE MALES 



1. Mesonotum without definite designs 2 



Mesonotum with definite designs, usually in the form of longitudinal or trans- 

 verse bands or lines 3 



2. Scutellum with long black hairs; postnotum bare; golden-yellow scalelike 



hairs on mesonotum dispersed in groups of 3 or 4 hairs to the group; all 

 hairs on abdomen black ; total length approximately 2.0 mm. 



Notolepria Enderlein, 1930 

 (Simulium (N.) exiguum Roubaud*)^ 

 Scutellum with long yellow hairs; postnotum usually with group of several 

 golden-yellow scalelike hairs ; scalelike hairs on mesonotum single ; abdomi- 

 nal hairs mainly long and yellow, with few short black ones along mid- 

 region; total length approximately 3.5 mm Ensimulium Roubaud, 1906 



(Simidium (E.) aureiim (Fries)*) 



3. Mesonotal designs always gray- or white-pruinose, formed in central region, 



extending from anterior margin posteriorly, without dark lines ; prescutellar 



region devoid of long hairs 4 



Mesonotal patterns in other form ; prescutellar region usually with long hairs 

 (exceptions : S. (S.) ochraceum and 5". (D.) piilverulenhim) 5 



4. Elongate gray-pruinose designs on either side of midline in form of two tri- 



angles having their bases anteriorly ; the smaller one has its base almost con- 

 tiguous to the anterior margin of the mesonotum and the larger one has its 

 base just posterior to the apex of the smaller triangle and slightly lateral 



to it Byssodon Enderlein, 1952 



{Simulium (B.) benjamini Dalmat*) 

 Elongate pruinose designs simple, not divided. 



Lanea Vargas, Martinez, and Diaz, 1946 



5. Mesonotum with either longitudinal dark lines contrasting with the base color, 



or with these lines plus longitudinal pruinose stripes. 



Dyarella Vargas, Martinez, and Diaz, 1946 



Mesonotum only with pruinose band around its periphery, the band being 



either complete or interrupted on the anterior margin 6 



^ Asterisk (*) indicates the only representative of the subgenus in Guatemala. 



