﻿50 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loo 



of the midtarsi, and a small area below at the apex of the hind femora. 

 The f oretibiae are often darkened on the apical third. Wings hyaline ; 

 squamae whitish yellow, the fringe dark yellow ; halteres yellow. 



Abdomen black with three pairs of yellow to whitish spots; first 

 segment black, sides yellow; spots on the second segment large, the 

 sides yellow except narrowly at the apex, inner ends of spots broad; 

 spots on the third segment occupy the anterior two-thirds, inner ends 

 whitish ; spots on the fourth segment whiter and much smaller, do not 

 reach sides, inner ends well away from the anterior margin. Genital 

 segments shining black with yellow pile; pile on rest of abdomen 

 j'^ellow to golden, black on black areas. 



Female. — Very similar to male, the front broad with a semishining 

 midstripe connecting the shiny black antennal prominence with the 

 opaque black of the ocellar area ; pile of the black areas black, becoming 

 brown below. 



Abdominal spots are narrower and there is an additional pair on the 

 fifth segment. 



Holotype^ male. — Matanuska Alaska, June 1944 (J. C. Chamber- 

 lin) ; U. S. N. M. No. 58822. 



Allotype, female, — Same data. 



Paratypes. — Four males and eight females, same data ; one female, 

 same locality, July 2, 1945. All these specimens were taken in the 

 rotary trap. 



This species is related to obscurus Loew (fig. 11, Z), but they are 

 readily separated by the complete thoracic vittae on neoa^7iis, which 

 on ohscurus is fainter and partially interrupted. A study of the geni- 

 talia indicates the close relationship of neoaifinis to affinis (fig. 11, j 

 and h). The males were compared with a specimen of affinis from 

 Lapland, and I can see no decided differences except in the genitalia. 



HELOPHILUS ALASKENSIS, new species 



Figure 11, c, d, g-i, m 



Diagnosis. — A medium sized gray-pollinose species. Ground color 

 of face mostly black. Mesonotal vittae very faint. Hind femora 

 quite slender. Length 9.5 to 12 mm. 



Male. — Head black, pollinose, a broad facial midstripe and the 

 cheeks shining ; a reddish streak on the sides of the face, running from 

 the base of the antennae to about two-thirds the distance to the epis- 

 toma, and becoming broader below. Front rather broad, grayish pol- 

 linose, the area between the depression and anterior ocellus about one 

 and one-half times wider than long; the pile of the head all white 

 except for a few black hairs across the ocelli and on the upper occiput. 

 A prominent reddish velvety spot just below each eye. First two 

 segments of the antennae black, the third reddish to brownish ; arista 

 reddish, the base brown, the tip black. 



