FLIES OF GENUS RR^ELLIA — NAJVIBA 69 



Allotype: Female. Body length about 5.0 mm.; wing length 3.2 

 mm., width 1.2 mm. Thorax dark brown; ovipositor sheath dark 

 brown. Otherwise similar to holotype. 



Paratypes: 7 males, 3 females. Body length of males 5.0-5.2 

 mm., of females 4.7-5.4 mm.; wing length of males 3.4-3.6 mm., of 

 females 3.3-3.6 mm. I have seen one female with one posterior 

 dorsocentral seta on the right side. Otherwise similar to holotype or 

 allotype. 



Specimens: Holotype, cf^, Buffalo Center, Iowa, July 7, 1928, 

 G. O. Hendrickson (ISC). Allotype, 9 , Ames, Iowa, June 18, 1926, 

 G. O. Hendrickson (ISC). Paratypes: Illinois: (299, Icf); 

 Champaign (19, Scfcf', May 27, 1889, Marten, "15005"). Iowa: 

 Ames "e" (1 cf , July 10, 1925, and 1 cf , May 31, 1926, G. O. Hendrick- 

 son); 7 miles northwest of Thompson (IcT, June 30, 1928, G. O. 

 Hendrickson). (In ISC, SEC, and INHS.) 



Remarks: The pronounced convexity of the postcranium, the 

 absence of both strong humeral and posterior dorsocentral setae, and 

 the pruinose abdominal tergites indicate affinity of this species to 

 R. hoscii. It can be distinguished from R. boscii by the ventrally 

 directed head, the presence of strong lateral scutellar setae, the lesser 

 amount of pruinosity on the sternopleuron and mesopleuron, the 

 male genitaha, and the presence of a complete shining median band 

 on the postscutellum. 



RiveUia succinata (Wiedemann) 



Figure l,a-c 



Dacus succinatus Wiedemann, 1830, p. 526. 



RiveiUa succinata (Wiedemann). Hendel, 1914a, p. 173, pi. 1, fig. 19; 1914b, 

 pi. 1. fig. 18. 



Type locality: "Vaterland?" (Wiedemann, 1830). Types de- 

 posited "Im Wiener Musseum und in meiner Sammlung" (Wiedemann, 

 1830). 



Males: Body length about 4.5 mm. 



Head: Frons yellow; upper fronto-orbital plates and ocellar triangle 

 yellow; inner vertical setae absent. Face with dorsal half pruinose, 

 ventral half shining, smooth, yellow; parafacials and part of orbits 

 ventral to each eye brownish yellow. Antenna completely yellow, 

 tip of thu-d segment pointed anteriorly. Anteclypeus yellow. Palpi 

 yellow. Postcranium yellow, lightly pruinose. 



Thorax: Mesonotum yellow; strong humeral setae absent, posterior 

 dorsocentral setae present. Scutellum yellow, somewhat brownish 

 at apex. Postscutellum concolorous with mesonotum. Pleura yellow, 

 mostly shining, pruinosity obscure except on laterotergite. Meso- 



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