﻿SOME ALASKAN SYRPHID FLIES — FLUKE 47 



cation of these forms and a misleading idea of the generic limitations 

 were caused. I think the group is somewhat natural and should 

 include versipellis Williston (nee Shannon) even though the front is 

 inflated and pilose. The characters on the antennae and wings are 

 weak and certainly deserve only subgeneric consideration. 



The material from Alaska contains a small series of dldshensis so 

 I take this opportunity to present a key to the species. C. W. Sabrosky 

 made careful comparisons of my material with both Shannon's and 

 Williston's types. Many of the notes given here and the sketches of 

 the type of versipellis were made by Mr. Sabrosky, and I wish to thank 

 him for permission to copy the pencil sketches he made for me. He 

 pointed out the genital and frontal characters used in the keys. 



KEY TO CHRYSOGASTER (BARBERIELLA) 



Mates 



1. Front inflated, with long black hairs near border, genital styles about three 



times as long as width measured at narrowest point versipellis (Williston) 



Front not inflated, without long pile, genital styles usually longer 2 



2. Front shining, with a patch of appressed microscopic hairs (pollinose) next 



to eye angle, genital styles long and slender alaskensis Shannon 



Front more rugulose, with a band of microscopic naplike hairs along eyes 3 



3. Downward-projecting pile on edge of scutellum yellow, genital styles similar to 



versipellis chilosioides Shannon 



Downward-projecting pile of scutellum black, genital styles four times as long 

 as narrowest width nigripennis (Williston) 



Females 



1. Antennae entirely black, front brownish pollinose alaskensis Shannon 



Antennae yellowish, at least below on third segment ; front shining 2 



2. Pile of mesonotum brown and black mixed, rather long. 



nigripennis (Williston) 

 Pile of mesonotum short and all brown, black only on rim of scutellum, 



versipellis? (Williston) 



CHRYSOGASTER (BARBERIELLA) ALASKENSIS Shannon 



FiGTJBE 10, fc, I, p 



CTirysogaster (Barieriella) alaskensis Shannon, Ins. lusc. Menstr., vol. 10, p. 

 125, 1922. 



Diagnosis. — Black ; front bare ; pile under scutellum long and yel- 

 low ; genital styles extremely long and slender. Length 8.5 to 9 mm. 



Male. — General color black with bluish reflections on the face ; pile 

 all black except that on the cheeks, sides of abdomen, basal areas of 

 the femora, and the downward-directed pile on the underside of the 

 scutellum ; the pile on these areas is generally whitish, somewhat yel- 

 low on the abdomen and scutellum. Front is bare, very shallowly 

 grooved and shining except for microscopic pollinose appressed hairs 

 in the angle formed by the eyes; face shining, with a prominent 



