420 U. S. NATIONAL MUSEUM BULLETIN 2 1 6 part s 



part of its upper valve a very little narrower than in L. multimaculata 

 and without a median longitudinal ridge. 



Head, body, and hind coxa black, marked with white about as in 

 figure 335,g or 336, a, or intermediate between these two figures, the 

 face of male being entu-ely white. Front of male scape, upper side of 

 the median 11 ± segments of male flagellum, and upper side of the 

 median 6± segments of female flagellmn, white; antenna otherwise 

 black except that under side of male flagellum is brown, paler medially; 

 palpi white; front and middle coxae brown or sometimes fulvous, more 

 or less white according to sex and subspecies, sometimes entirely white, 

 the white more extensive in males and in the subspecies albomaculata; 

 hind coxa black, with a large white spot above in the subspecies 

 albomaculata, the white spot smaller or absent in the subspecies sagax; 

 hind trochanters and femur fulvous, the apical 0.2 ± to 0.5 ± of the 

 femur fuscous, the fuscous area averaging more extensive in males; 

 hind tibia black with a subbasal white band; first segment of hind 

 tarsus varying from fuscous with a narrow basal and wider apical white 

 band, to entu-ely white; segments 2-4 of hind tarsus white; segment 

 5 of hind tarsus black, its base often white. Spechnens from the 

 western edge of the range (Alberta, Missouri, and Kansas) have the 

 apical fuscous area on the hind femur reduced. In these it occupies 

 only about the apical 0.1 and is not very dark. 



There is a northern and a southern subspecies, differing m the ex- 

 tent of white markings, as defined below. Females can be distin- 

 guished rather sharply, but males of the two subspecies are not 

 distinguishable with certainty. 



1. Mesopleurum of female without a white spot above sternaukis; white markings 

 on head, body, and coxae less extensive; range: Atlantic to Rocky Mts. in 

 Canadian and Transition zones . . 7a. albomaculata sagax (Provancher) 

 Mesopleurum of female with a white spot above sternaulus; white markings 

 on head, body, and coxae more extensive; range: Alleghanian, Carolinian, 

 and Austroriparian faunas . . 7b. albomaculata albomaculata (Cresson) 



7a. Listrognathus (Listrognathus) albomaculata sagax (Provancher) 



Figure 335,g 



Mesostenus sagax Provancher, 1879, Naturaliste Canadian, vol. 11, p. 112 (Faune, 

 p. 345); ?. Type: 9, Cap Rouge, Quebec (Quebec). 



Male: Similar to the male of L. alhom.aculata albomaculata but with 

 white markings averaging a little smaller. 



Female: Head and body marked with white approximately as in 

 figure 335,g, the mesopleurum without a white spot above sternaulus. 

 Front wing usually with a faint infuscation medially. 



Specimens (1 cf , 299) : From Alberta (Edmonton and Medicine Hat) ; 

 New Brunswick (Jacquet River) ; New Hampshu-e (Mount Washmg- 



