FLIES OF GENUS RIVELLIA — NAMBA 35 



mainder yellow; femora and tibiae yellow; tarsi wholly yellow or 

 slightly blackened from third segment. Hind legs: Coxae yellow to 

 yellowish brown; femora yellow; tibiae yellow to yellowish brown; 

 tarsi wholly yellow or slightly blackened from third segment. 



Wing (fig. 9,h) length 2.2-3.3 mm. Bands brown; much reduced, 

 somewhat similar to those of R. vaga. First band consists of spot at 

 junction of second and third veins. Second band extends from 

 proximad of tip of first vein to fom-th vein over the anterior crossvem, 

 faint between second and thu-d veins. Third band extends from 

 proximad of tip of second vein toward posterior crossvein but not 

 surpassing fourth vein. Fourth band extends from about half way 

 between tips of second and third veins to tip of fom'th vein. Some- 

 times all bands obsolete. Section of fourth vein proximad of anterior 

 crossvein straight or with very slight bend. The part of first basal 

 cell contiguous to second basal cell completely hyaline. Anal angle 

 prominent. Halteres yellow. 



Abdomen: Tergites shining, rugose, dark brown or black with blue- 

 green reflections. Disc of first tergite with pale setae. Genitaha (fig. 

 9,j,k) with apical part of the aedeagus flattened dorsoventrally, shaped 

 like an elongated lyre from dorsal view. 



Females: Body length 3.5-4.5 mm.; wing length 2.6-3.3 mm. 

 Ovipositor sheath concolorous with abdominal tergites. Otherwise 

 similar to males. 



Specimens examined: Georgia (399, Icf): Augusta, Tybee Island; 

 June 4-July 26. Illinois (19): Bishop; June 23. Kansas (19, 

 2 cf (f ) : Saline County, Medora (sand dunes) ; June 7-8. Maryland 

 (299) : Bladensburg; June 23. Michigan (299) : St. Joseph; June 23. 

 Mississippi (Icf): Oxford; May. North Carolina (899, 3^^^"): 

 Raleigh; April 16-June 28. New York (699, 5cf cf): Farmingdale 

 (Long Island) ; June 6. 



Remarks: This species can be distinguished from other Rivellia by 

 the shape and banding of the wings and the male genitalia. 



Rivellia maculosa, new species 



Figure 5,j-l 



Holotype: Male. Body length about 2.7 mm. 



Head : Frons reddish brown ; upper fronto-orbital plates and ocellar 

 triangle blackened. Face with dorsal half pruinose, ventral half 

 shining, smooth, brown ; parafacials and part of orbits ventral to each 

 eye brownish yellow. Antenna with first and second segments yellow; 

 third segment blackened at tip and on outside, remainder yellow, the 

 tip pointed anteriorly. Anteclypeus brown. Palpi brown. Post- 

 cranium black, pruinose. 



