40 U.S. NATIONAL MUSEUM BULLETIN 2 80 



Key to the Species Groups of Arivaca Based Upon the Maculation 



1. Cubitus with prominent white streak; white band anterior to cell (figs. 19, 



20) ostreella group 



White trace of cubitus not prominent, absent if white band present anterior 

 to cell 2 



2. M2+3 stalked; forewing not appearing lighter anterior to cell (figs. 15, 16). 



pimella group 

 M2+3 fused; forewing somewhat lighter anterior to cell 3 



3. Forewing ground uniform reddish brown, prominent white band anterior 



to cell (Florida) albicostella group 



Forewing gray, mixture of black and white scales, radius and subcosta white 

 traced (west of Mississippi River) albidella group 



The Pimella Group 



Diagnosis. — This group may be distinguished by the male valvae, 

 in which the costa ends in a short triangular tooth well before the 

 rounded tip of the cucullus. A similar projecting membranous cucullus 

 exists in albicostella, but the costa terminates in a stout spine in that 

 species. 



Description. — ^Frons light brown to brown; labial palpi with basal 

 segment white, second and third segments clothed with white-tipped 

 brown scales dorsally and on outer sides, white ventrally and on inner 

 sides; vertex Ught brown anteriorly, white posterior to antennae, 

 occiput, patagia, and tegulae brown laterally, lighter dorsally; legs 

 clothed with white-tipped brown scales on outer sides, white on inner 

 sides. 



Forewing ground Ught orange brown, veins white traced and 

 bordered -with brown, Ai and A2 traced for most of their length, A3 

 traced at base; 11 veins; M2+.3 stalked. Hindwing hght brown, fringe 

 white; 7 veins; M3 usually free from lower outer angle of cell. 



Male genitaUa with uncus moderately well sclerotized between 

 spicate processes. Juxta rounded, with caudal V-shaped notch. Valvae 

 with costa sparsely setose, apically bearing short triangular tooth; 

 cucullus with rounded membranous tip projecting well beyond costa; 

 sacculus with patch of stiff setae. Aedeagus with cornuti serrate, 

 small, subequal. 



Female genitalia with base of posterior apophyses flat, shaped Uke 

 parallelogram. Bursa unarmed. 



Discussion. — The two included species may be separated by the 

 condition of vein R2, which is stalked with R3+4 in linella but free 

 in pimella, but this character is usually variable elsewhere in the sub- 

 family so that positive identification should rest with examination of 

 the male genitalia. 



