114 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5 1 



RHACHOEPALPUS, gen. nov. 



This genus is proposed for Saundcrsia testae ea van der Wulp. 

 Mr. van der Wulp has remarked on the striking resemblance which 

 this species bears to Paradejeania rutilioides. 



Rhachoepalpus olivaceus, sp. nov. 



Two specimens, male and female, collected on the head of Rio 

 Piedras Yerdes, about 7,000 feet, Sierra Madre of western Chihua- 

 hua (Townsend), one on flowers of Rhus glabra, July 15, the other 

 August 16. 



Length of male, 18.5 mm. ; of female, 19 mm. Thorax with an 

 olive green tinge. Frontalia with much the same tinge, but darker. 

 Second antennal joint with a strong bristle on front border near 

 distal end, sometimes a pair of them. Third joint only a little longer 

 than second, hardly one and one-half times as long, same size in both 

 sexes. Arista thickened on rather more than basal half, distinctly 

 jointed, second joint elongate. Scutellum with at least four rows of 

 spines. The male shows a median dorsal stripe on abdomen, 

 widened in front on second segment, where it is marked by an area 

 of spines, narrower on third segment, and narrowest, but still dis- 

 tinct, on anal segment. This stripe shows only on anal segment in 

 female, but the area of spines is present on second segment. The 

 anal segment in both sexes is gently emarginate in middle on hind 

 border, presenting a double curve like a pair of buttocks. Wings 

 evenly infuscated. Color of scutellum is same in both sexes — quite 

 yellowish. Abdomen of male is of a distinctly more reddish shade, 

 female abdomen being of nearly same shade as scutellum, if any- 

 thing, slightly lighter. Claws of female are yellow, with black tips. 

 Front of female is wider, with three proclinate fronto-orbital bristles 

 on one side and only two on the other. Front tarsi of female not 

 dilated. 



Type.— Cat. No. 10,915, U. S. X. M. 



Rh. olivaceus bears the same striking resemblance to Paradejeania 

 that Rh. testaccus does; perhaps even more so, since in the latter 

 there seems to be no posterior emargination of anal segment on the 

 median line. Mr. van der Wulp's figure shows none, and his text 

 mentions none. 



Rhachoepalpus shows broad ventral plates in both sexes, but ven- 

 tral membrane in female is not visible. There are five abdominal 

 segments, the first very short and barely discernible from the side. 

 The female shows ventral plates, bearing thick bunches of spines, 

 corresponding to second to fifth dorsal plates, the lateral edges of 



