FLIES OF THE GENUS OGCODES — SCHLINGER 293 



tribution of pallidipennis greatly, and has allowed me to question 

 the validity of aedon Townsend and humeralis Osten Sacken. 



Specimens from Mexico, southern California, New Mexico, and 

 Texas were compared with the original descriptions of aedon and 

 humeralis. No specific differences could be detected, and an exam- 

 ination of the male genitalia of the Guadalajara specimen revealed 

 it was typical pallidipennis. The female from Chihuahua was a 

 little darker than that described for humeralis, but the type of the 

 latter was stated to be a male, and the males of pallidipennis are 

 usually lighter than the females. 



The type of aedon was destroyed in the California Academy of 

 Sciences Museum in the San Francisco fire of 1906. Townsend 

 (1895) said in his original description: "Very similar to Oncodes 

 humeralis O.S., but differs in the tegulae being fuscous whitish with 

 well defuied narrow dark brown margins." This latter character 

 appears to be the only one which might differentiate aedon from 

 humeralis and pallidipennis. However, it has been found that the 

 degree of infuscation of the squama in species of the pallidipennis 

 group is somewhat variable, and is therefore a doubtful specific 

 character (see discussion under adaptatus). Since the other specific 

 characters mentioned in the descriptions of aedon and humeralis 

 agree well with pallidipennis, and since the range of the latter is 

 now known to extend well beyond the limits of the type localities 

 of the two species involved, it seems reasonable to suspect this 

 synonymy. 



Many earlier authors have confused pallidipennis with such species 

 as eugonatus and melampus and with specimens now known to be 

 adaptatus, new species. Sabrosky (1944, p. 392) was the first to 

 recognize that synonymy was involved and noted that costatus was 

 the light-colored male and incultus the dark-colored female of palli- 

 dipennis. The specimens cited above from Costa Rica are of this 

 dark "incultus" form. 



Light-colored specimens of borealis and dark-colored specimens of 

 dispar also might be confused with pallidipennis females. However, 

 the characters given in the key to the species should be sufficient to 

 separate them. 



I believe that pallidipennis is the most primitive member of group 

 v in North America and presume that it gave rise to the closely 

 related dispar (see text fig. 3). The European species varius is quite 

 closely related to both of the former species as well as to the Nearctic 

 rufoabdominalis. The male genitalia will separate all the above species 

 as well as adaptatus. The last, although not closely related, has been 

 associated with pallidipennis by Sabrosky (1948) and Kessel (1948). 



