FLIES OF GENUS RIVELLIA — NAMBA 31 



second bands joined broadly to thii'd band posterior to fifth vein. 

 Section of foiu'th vein proximad of anterior crossvein with definite 

 bend. Halteres with dark brown capitulum, pedicel brownish 

 yellow. 



Abdomen: Tergites shining, rugose, black. Disc of first tergite 

 with no pale setae evident. Genitalia (fig. 6,^,j) with apical part of 

 aedeagus consisting of a bulbous base and two filamentous terminal 

 tubes which are subequal in length to bulbous base. 



Females: Body length 3.5-5.4 mm; wing length 3.0-4.0 mm. 

 Ovipositor sheath black. Otherwise similar to males. 



Specimens examined: Connecticut (19): Willington; no date. 

 Kansas (299, Icf): Baldwin, Douglas County, Medora (Sand 

 Dunes) ; May 26-July. Massachusetts (4 cT cf ) : Atco, Brown Mills, 

 Buena; June 11-25. New York (499, 5cf cf): Farmingdale (Long 

 Island); June 5-14. North Carolina (299, Ic^): Pmebluff, 

 Raleigh, Toxaway; May 24-29. Oklahoma (19): Afton; May 16. 

 Virginia (299): Falls Church, Veitch; June 9. Texas (1099, Icf): 

 College Station, Liberty, Walker County; March 25- April 21. 



Remarks: The salient character of this species is the wing banding. 

 The absence of prumosity on the posterior part of the mesopleuron 

 and the rather broad pruinose strip on each side on frontal orbits are 

 also peculiar to this species. 



Rivellia tersa, new species 



Figure 8, a-c 



Holotype: Male. Body length about 4.6 mm. 



Head: Frons yellowish brown; ocellar triangle black; upper fronto- 

 orbital plates concolorous with frons. Face with dorsal half pruinose, 

 ventral half shming, rugulose, yellow; parafacials and part of orbits 

 ventral to each eye brownish yellow. Antenna with first and second 

 segments brownish yellow; third segment with outside and anterior 

 part of inside blackened, remainder yellow, the tip pointed anteriorly. 

 Anteclypeus concolorous with ventral portion of face. Palpi yellow. 

 Postcranium yellowish brown, lightly pruinose. 



Thorax: Mesonotum pale brownish yellow, with black and brown 

 blotches which are probably due to contents of thorax ; strong humeral 

 and posterior dorsocentral setae present, in addition a pair of setae 

 anterolateral to posterior dorsocentral setae present. Scutellum and 

 postscutellum unicolorous, pale brownish yellow. Mesopleuron with 

 pruinose area at dorsal posterior corner m form of right triangle, one 

 side reaching half way to ventral posterior corner, the other side 

 reaching half way to anterior spu-acle. Sternopleuron with ventral 

 corner and narrow strip on posterior margin pruinose; disc with 

 scattered pale setae. Disc of pteropleuron with scattered pale setae. 



