70 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



6. Relative length of hind basitarsus to second segment 4.8-5.1 : i, average 5:1; 



hind basitarsus about 4 times longer than broad Simulium, s. str. 



Relative length of hind basitarsus to second segment 2.4-4.2: i, average, 3.8: i ; 

 hind basitarsus about 2.8 times longer than broad Hearlca Rubzov, 1940 



subgenera of the genus simulium, based on male genitalia 

 (alternate key) 



1. Clasper half, or less, the length of sidepiece 2 



Clasper more than half the length of sidepiece 3 



2. Clasper broad at base, tapering to point at apex ; terminal spine so small it can 



be seen only as a minute point on apex of clasper ; external border of clasper 

 strongly arched so that the apex almost reaches the sidepiece ; body of ad- 

 miniculum approximately triangular in shape, its basal prolongations very 



short Notolepria Enderlein, 1930 



{Simulium (N.) exiguum Roubaud*) 



Qasper rather narrows at base, vnth humplike expansion near the middle of its 



external border, the apex truncate; terminal spine very well formed, stout, 



on inner angle of apex; adminiculum in form of inverted Y, the apex very 



acutely angular, the other two basal prolongations broad. 



Eusimuliiim Roubaud, 1906 

 (Simulium (E.) aureiitn (Fries)*) 



3. Clasper conical 4 



Clasper not conical ; either quadrangular, cylindrical, or in other form S 



4. Clasper inserted at middle of apical margin of sidepiece, approximately equi- 



lateral, with single, terminal spine on inner angle of truncate apex ; terminal 

 spine bifid from near its middle to the extremity ; sidepiece without dorsal 

 concavity near apex ; body of adminiculum almost triangular in shape. 



Byssodon Enderlein, 1925 

 {Simulium (B.) beiijaiiiini Dalmat*) 

 Clasper inserted inward from the middle of apical margin of sidepiece ; outer 

 margin of clasper longer than inner, the clasper arched with convexity on 

 outer surface ; terminal spine small, undivided, close to rounded apex ; side- 

 piece with concavity on outer dorsal region near apex ; body of adminiculum 



semicircular to quadrangular in shape Simulium (Simulium) ochraccum 



Walker (exception to usual form of species belonging to subgenus 



Simulimn) 



5. Clasper flattened, somewhat quadrangular, with the inner angle of apex usu- 



ally elongated; clasper shorter than sidepiece. 



Lanea Vargas, Martinez, and Diaz, 1946 

 Clasper cylindrical in shape, longer than sidepiece 6 



6. Clasper sinuous, caused by expansions along one or both margins ; length of 



clasper approximately 3.0-3.7 times its width. 



Dyarella Vargas, Martinez, and Diaz, 1946 

 Qasper with its margins not sinuous 7 



7. Clasper from 6-8 times longer than broad; adminiculum broader than long, 



the body appearing almost rectangular in shape (except S. (H.) larvi- 

 spinosum De Leon, the adminiculum of which is longer than broad and the 



body of which is in form of a pointed arch) Hearlca Rubzov, 1940 



Clasper 3.0-4.5 times longer than broad; adminiculum longer than broad, its 

 apex rounded or truncate (S. (S.) tricornis DeLeon), but never pointed 

 (S. (S.) ochraceum Walker keys out in couplet 4) Simulium, s. str. 



