284 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



projecting above mesal portion of 

 lateral lobes; ventral structure of 

 bursa copulatrix very narrow, fig. 



950 sierra n. sp. 



Mesal lobe of subgenital plate pro- 

 jecting conspicuously beyond mesal 

 portion of lateral lobes; ventral 

 structure of bursa wider, fig. 951 .. . 

 ardis Ross 



Oligophlebodes sierra new species 



In color this species approaches most 

 closely sigrna but differs from it in the 

 twisted apex of the claspers, large lateral 

 lobe of the ninth segment and other char- 

 acters of the genitalia. The female may be 

 distinguished from other members of the 

 genus by the combination of the narrow 

 ventral lobe of the bursa copulatrix and 

 the low and evenly sloping lateral lobes 

 of the ninth sternite. 



Male. — Length 8 mm. Color yellowish 



brown, the wings without conspicuous 

 darker markings. General structure typical 

 for genus. Genitalia as in fig. 943. Ninth 

 segment reduced to a line dorsally, expanded 

 into a wide ventral portion which is pro- 

 duced on the meson into a short angular 

 process; the lateral margin bears a platelike 

 projection which is wide and high and equal 

 to the lateral aspect of the claspers in area. 

 Each clasper with a rounded base and a 

 short, apical blade which is twisted into an 

 almost vertical position and appears some- 

 what beaked in the lateral view. Tenth ter- 

 gite entirely membranous, consisting of con- 

 cave and inconspicuous membranous folds. 

 Cerci triangular, small and bearing long 

 setae. Aedeagus membranous and tubular 

 and containing a pair of sclerotized rods. 



Female. — In size, color and general 

 structure similar to male. Subgenital plate, 

 fig. 950, with a low, narrow mesal lobe and 

 wide, sloping lateral lobes; bursa copulatrix 



947 



SIGMA Q 



'^~-^_-'' 946C 



Figs. 9^i-9^7. —Oligophlebodes, male genitalia. A, B and C, respectively lateral, ventral 

 and dorsal aspects. 



