84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



Respiratory apparatus with 26 branches ; dorsum of thorax with granulosity ; 

 outermost 2 spines on either side of transverse row on second abdominal 

 segment anterior to spines closer to midline; ventral surfaces of segments 

 6 and 7 with only 2 spines ; margin of anterior aperture of cocoon not 

 thickened, with long dorsal prolongation jacmnbae Dyar and Shannon 



5. Respiratory apparatus consisting of three inflated tubular branches, arising 



from common base, one above the other, all directed anteriorly, appearing 

 like a pitchfork; superficial transverse divisions well marked. 



kompi Dalmat 

 Respiratory apparatus not in this form, branches not arising regularly 6 



6. Respiratory apparatus inflated, the narrow base expanding and soon dividing 



into two branches, each of these again subdividing irregularly ; dorsal ele- 

 ment of apparatus with numerous hairs on most of its dorsal face ; cocoon 

 appearing circular in shape when viewed from above, with short "ribbon" 

 joining both sides of cocoon beneath anterior aperture; dorsal surface of 

 segments 5 and 6 without spines or combs. 



parrai Vargas, Martinez, and Diaz 

 Respiratory apparatus consisting of a 3-branched structure, each branch tubu- 

 lar and tapering toward the apex, without hairs ; cocoon triangular in shape 

 when viewed from above, with heavily sclerotized ridge running along its 

 midline for the entire length of the dorsal surface ; without ventral "ribbon" ; 

 dorsal surface of segments 5 and 6 entirely covered by comblike groups of 

 minute spines tricornis De Leon 



GENERA OF SIMULIIDAE AND SUBGENERA OF THE GENUS SIMULIUM, 

 BASED ON LARVAL CHARACTERS ^ 



1. Mandible with 1-3 teeth along the inner margin Simulium Latreille, 1802 



Mandible vdth more than 3 teeth along the inner margin 2 



2. Submentum with 13 apical teeth Cnephia Enderlein, 1921 



Submentum with 17 apical teeth Gigantodax Enderlein, 1925 



3. Occipital cleft lacking or very poorly formed; anal gills consisting of three 



single, fingerlike processes Eusimulium Roubaud, 1906 



(Simulhtm (E.) aureum (Fries)*) 

 Occipital cleft always present and well formed 4 



4. Antennae 5-segmented, the second segment showing further superficial divi- 



sions, indicated principally by color bands Hearlea Rubzov, 1940 



Antennae 4-segmented, the second segment either simple or showing signs of 

 secondary divisions 5 



5. Posterior sucker with 150 or more rows of hooks. 



Dyarella Vargas, Martinez, and Diaz, 1946 

 Posterior sucker with less than 150 rows of hooks 6 



6. At least second segment of antenna usually with transverse striations; when 



these are lacking (in 6". (S.) ochracciim) , the occipital cleft reaches the 



submentum Simulmm, s. str. 



Antennal segments without transverse striations ; occipital cleft never reach- 

 ing submentum 7 



7. Rectal scales present, forming easily visible dark band across dorsum of eighth 



segment ; posterior sucker with 68-72 rows of hooks ; eighth segment with- 



^ Subgenus Byssodon not included because of lack of larval forms. 



