FLIES OF THE GENUS OGCODES — SCHLINGER 285 



on tcrgites, much wider ones on sternites; abdomen with short 

 pile about as in adaptatus; legs dark brown, only Imees light brown; 

 venation entirely unlike that of male (shown in pi. 4, fig. 21), being 

 more like that shown for gihhosus (in pi. 3, fig. 13) except r-m cross- 

 vein much shorter, thus crossvein m-cu absent, vein Mi faint, not 

 joining R4+5 as in male, anal vein separated from vein Cu2 towards 

 wing margin, but veins M2, M4, Cu2 and R4+5 as in male; squama heav- 

 ily infuscated. 



If this specimen represents the female sex of colei, which I believe 

 to be the case, then one might speculate on the reason for the great 

 venational dift'erences occurring between the sexes. It might be that 

 since the ovipositional habits of the known species (see biology 

 section) show that females may spend the majority of their adult 

 lives resting or walking on dead twigs depositing eggs, and since 

 flight may be only instigated during mating, that a weaker or more 

 simplified type wing venation evolved in the female sex; while the 

 need for flight in the males, in order to better search out the resting 

 females, has perhaps mandated the need for a primitive, and hence 

 stronger type, wing venation. Although this does not appear to be 

 the case in the closely related vittisternum, this condition might occur 

 in horealis, in which case it might help to explain the wing venational 

 difi'erences observed there (see under horealis above). 



Females of the other known Nearctic species of the colei group, 

 i.e.jfloridensis and shewelli, are unknown, so that a comparison cannot 

 be made with these species at this time. However, a similar situation 

 may exist with niger (see below). Also, if dimorphism of this type 

 should be proved, keys to the individual sexes would be a necessity. 



Text figure 3 shows the relationships of colei to the Nearctic Ogcodes 

 species, and there is little doubt that vittisternum is its closest relative. 



Ogcodes (Ogcodes) vittisternum Sabrosky 



Plate figures 63, 96 



Ogcodes vittisternum Sabrosky, Amer. Mid. Nat., vol. 39, p. 420, pi. 1, figs. 2-3, 

 1948. 



Diagnosis: Species of group iv. Male abdomen patterned, without 

 obvious tergal white fasciae, similar to colei but tergite iii with 

 distinct brown lateral spots; venter in both sexes with median and 

 lateral brown spots on each sternite; venation as in colei (pi, 4, fig. 21); 

 male genitaha similar to colei but the aedeagus is not as acuminate 

 (pi. 10, fig. 63) and ejaculatory apodeme stronger, more like she- 

 welli (pi. 12, fig. 96). 



Type: Holotype cf , Homestead Inn, Mount Hood, Oregon, July 

 6, 1927 (E. C. Van Dyke, FRC). 



