280 PROCEEDINGS OF THE ACADEMY OF [PaRT II 



margins there broadly convex-convergent to a small distal emargina- 

 tion. Subgenital plate large, convex; margins below cerci concave, 

 broadly convex between these points. 



Coloration of sexes similar. Entire insect shining blackish brown, 

 except as follows. Eyes tawny olive, ocellar spots buffy. Ant- 

 ennae and limbs paling to chestnut brown distad. Pronotum mar- 

 gined cephalad and laterad with a band of warm buff, this band 

 narrowest cephalad, the immediate lateral margins narrowly black- 

 ish brown. Tegmina translucent except in darker portions; mar- 

 ginal field warm buff, the cingulate margin blackish brown paling 

 to ochraceous-tawny distad; humeral trunk suffused with blackish 

 brown in proximal two-thirds, remaining portions ochraceous- 

 tawny with interval l^etween costal veins and veins of anal and 

 proximal portion of discoidal field buffy. Frequent individuals are 

 more strongly ferruginous in area between the humeral trunk and 

 sutural margin of the tegmina. Wings transparent, anterior field 

 tinged with ochraceous-tawny, the veins and entire area of costal 

 veins of this color; radiate field weakly tinged with ochraceous- 

 tawny. 



Measurements {in millimeters) . 



Length of Length of Width of Length of Width of 



c? body pronotum pronotum tegmen tegmen 



Icano, Argentina, <;/?^e 20.5 4.9 6.7 19 6 



Icano, Argentina, paraiypes (4) 19.3-22 4.3-4.8 6.2-6.8 18-19.6 6-6.3 



Barrancas, Argentina 17.8 4.8 6..6 18.7 6.2 



9 



Icano, Xrgentma,, allotype 19.2 5 6.8 122 5.1 



Icaiio, Argentina, 7Jara<7//>e 17 4.8 6.7 11.8 5.7 



Barrancas, Argentina (3) 19.8-20 4.7-5.3 6.5-7 12.7-13.1 5.1-5.8 



Troncal, Argentina 18.8 4.8 6.8 12.2 5.2 



It is of interest to note that, though the adults of this species do 

 not show the microscopic prostrate hairy covering usual in Nycti- 

 borids, that condition is shown, though not strongly, in the im- 

 mature stage. The immature individual before us has the prono- 

 tum marked as in the adults, the mesonotum and metanotum. 

 bordered laterad more broadly with buffy, each of these areas 

 crossed by a band of blackish brown, the four larger abdominal 

 tergites with an elongate, narrow, longitudinal marking on each 

 side of buffy, the immediate lateral margins being dark. 



Specimens Examined: 14; 7 males, 6 females and 1 immature in- 

 dividual. 



Border of Rio Salado, near Icafio, Santiago del Estero, Argentina, 

 2 cT, 2 9, type, allotype, paratypes,! juv. 



Guarda Escolta, near Icano, Santiago del Estero, Argentina, 4 cf. 



Barrancas, Banados del Rio Dulce, Santiago del Estero, Ar- 

 gentina, 1 cf, 3 9 . 



Troncal, Santiago del Estero, Argentina, 1 9 . 



