FLIES OF GENUS RIVELLIA — NAMBA 43 



Females: Since I cannot distinguish between the females of this 

 species and R. imitabilis, only females collected by me in the same 

 local population at the same time with the males of this species are 

 considered: Body length 3.2-3.7 nun.; wing length 2.6-2.8 mm.; 

 ovipositor sheath yellow at base, blackish toward apex. Otherwise 

 similar to males. 



Specimens Examined: Minnesota (2899, 21d'd^): Sucker Lake 

 (Ramsey County) ; June 24-July 24. 



Remarks: The males of this species can be separated from the 

 other species by the wing banding, genitalia, and yellov/ish body 

 color. Members of this species have been collected on Amphicarpa 

 bracieata (L.) Femald. 



Rivellia itnitabiliSf new species 



Figure 3,a-d 



Holotype: Male. Body length about 3.9 mm. 



Head: Frons yellowish brown; upper fronto-orbital plates concolor- 

 ous with frons, ocellar triangle slightly blackened. Face with dorsal 

 half pruinose, ventral half shining, smooth, pale yellow; parafacials 

 and part of orbits ventral to each eye yellow. Antenna with first 

 and second segments yellow; third segment blackened anteriorly, 

 remainder yellow, the tip pointed anteriorly. Anteclypeus yellow. 

 Palpi yellow. Postcranium pale brownish yellow, pruinose. 



Thorax: Mesonotum brownish yellow ; strong humeral and posterior 

 dorsocentral setae present. Scutellum and postscutellum concolorous 

 with mesonotum. Pleura browTiish yellow, mostly shining, prumosity 

 obscure except on laterotergite. Mesopleuron with scattered pale 

 and black setae on posterior one-thu-d ; sternopleurou with few scat- 

 tered pale setae on disc; pteropleuron with few scattered pale setae, 

 few black setae present ventral to subalar. Laterotergite completely 

 pruinose. Prosternum yellow. 



Thoracic appendages: Coxae and femora of all legs yellow; front 

 and middle tibiae yellow, hmd tibiae brownish yellow; front tarsi 

 blackened from fourth segment, remaining segments yellow, middle 

 and hind tarsi with fifth segment blackened, remaining segments 

 yellow. 



Wing (fig. 3, a) length 3.1 mm., width 1.4 mm. Bands brown. 

 First and second bands separated at costal margin; third and fourth 

 bands narrowly joined at costal margin. The part of first basal cell 

 contiguous to second basal cell completely hyaline. Section of 

 fourth vein proximad of anterior crossvein with slight bend. Hal- 

 teres light brown. 



