FLIES OF GENUS RIVELLIA — NAMBA 27 



26 (25). Second band as broad as or narrower than hyaline strip between first 

 and second bands; second basal and anal cells not banded. 



R. inaequata, new species 



Second band much broader than hyaline strip between first and second 



bands; second basal and anal cells banded . R. succinata (Wiedemann) 



27(25). Femora of front legs blackish R. socialis, new species 



Femora of front legs uniformly yellowish 28 



28 (27). Posterior dorsocentral setae absent; abdominal tergites distinctly 



pruinose ; head directed anteriorly . . R. boscii Robineau Desvoidy 



Posterior dorsocentral setae present; abdominal tergites not pruinose; 



head directed ventrally 29 



29 (28). Thorax and abdomen usually unicolorous, dark brown or black. 



R. steyskali, new species 

 Thorax dark brown, black, or blackish green; abdomen j'ello wish . . 30 



30 (29). Males with setae on fourth abdominal sternite directed posteriorly; 



aedeagus with apical part consisting of a long cylindrical neck, a small 

 spherical head, and two long terminal tubes . . R. colei, new species 

 Males with setae on fourth abdominal sternite radially directed; aedeagus 

 with apical part consisting of a bulbous base and two relatively short, 

 slender, terminal tubes R. quadrifasciata (Macquart) 



RivelUa Jloridana Johnson 



Figure 2,d 



RivelUa jloridana Johnson, 1900b, p. 247.— Hendel, 1914a, p. 175. 



Type locality: Dayton Island, Lake George, Fla. (ANSP). 



Females: Body length about 5.0 mm. 



Head: Frons brownish yellow or yellow; ocellar triangle blackened, 

 upper fronto-orbital plates concolorous with frons. Face with dorsal 

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

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

 second segments yellow; third segment with outside and anterior 

 two-thu-ds of mside, or outside, only faintly blackened, remainder 

 yellow, the tip pointed anteriorly. Anteclypeus concolorous with 

 ventral portion of face. Palpi yellow. Postcranium yellow, lightly 

 pruinose. 



Thorax: Mesonotum yellow; strong humeral and posterior dorso- 

 central setae present. Scutellum and postscutellum concolorous with 

 mesonotum. Pleura yellow, m.ostly shinmg, pruinosity obscure 

 except on laterotergite. Mesopleuron with posterior half rather 

 densely covered with black setae; sternopleuron with black setae on 

 disc; pteropleuron with black setae ventral to subalar. Laterotergite 

 completely pruinose. Prosternum yellow. 



Thoracic appendages: All legs yellow except for front and hmd 

 tarsi, which are very slightly blackened from third segment. 



Wing (fig. 2,d) lengths of the two specimens examined are 3.7 and 

 4.1 mm. Bands brownish yellow, broad. First band broad at base, 

 covers second basal cell and extends beyond discal cell where it faintly 



